Astronomy and Space

Endings and New Beginnings

2011-05-23T18:09:00.000-07:00

I am moving this blog from Blogger and to Tumblr. There will be no more updates here, and all new updates will be at this new location.

Essentially, the reasoning behind the move was that Blogger was no longer a good fit for the way I wanted to maintain this blog. Don’t get me wrong, Blogger is a wonderful platform, and still has a few advantages over Tumblr. However, what it came down to for me was that Blogger was not implementing a few core features that I desperately wanted to use, such as greater control over editing the theme.

This is a particularly emotional decision for me since this was the place where I first started writing seriously about astronomy and space, and the experience has taught me so much. Even though this move does not signify at all an ending of what I love to do, it is the ending of a big chapter of it. But with that ending, has come a new beginning, one that will allow me to better achieve the goals I have wanted for the project. Something I have started to value, especially recently, is the ability to remain agile and quickly adopt something new and better for me, and not hold onto the past for its own sake.

With that, this location should remain completely functional for archival purposes, but all new updates will be found here. Thanks for all your support.

New Candidate for Coldest Known Star May Help Blur the Distinction Between a Star and a Planet

2011-03-25T22:59:00.000-07:00

An artist’s impression of the CFBDSIR 1458+10 star system.
The star in the background is the candidate for the coldest known star.
Image: ESO/L. Calçada

There may be a new candidate for the coldest known star, an object classified as a brown dwarf with a surface temperature of only about 100 degrees Celsius. The temperature is close to the boiling point of water which is hot when compared with temperatures obtained on the surface of the Earth. In cosmic terms, however, this temperature is remarkably cold, in fact about 55 times colder than the surface of the Sun. Yet, the title for the coldest star rests on an important distinction: is this particular object a star, and can the definition of a star actually change?

This particular cool object, named CFBDSIR 1458+10B, is part of a binary star system at a distance of about 75 light-years from the Earth. Both parts of the binary system are classified as brown dwarfs¹, and are about the size of Jupiter. They orbit each other at a separation distance of about 3 AU, or 3 times the distance from the Earth to the Sun, in a time period lasting 30 years. The system was detected last year by the Very Large Telescope, part of the European Souther Observatory in Chile. At first it was thought to be a single star with a very low temperature², but the presence of a smaller even colder companion made it much more interesting.

A color image of the star system made using four different filters at near-infrared wavelengths.
Captured at the Keck II Telescope in Hawaii. Image: Michael Liu, University of Hawaii.

Brown dwarfs are often considered failed stars, and are objects that are not able to gather enough mass so that their gravity can trigger the Hydrogen-1 fusion reaction that takes place in the cores of most other stars. Smaller brown dwarfs, due to their low mass, begin to more closely resemble gas giant planets. There is still a lingering question on whether or not this object can, or even should be considered a brown dwarf and a star. The most simple distinction between stars and planets is whether or not there is any fusion taking place inside the star. By this definition, the cutoff point occurs at about 13 times the mass of Jupiter. At this mass, objects start to fuse deuterium and can be considered stars. Since the mass of this object is between 6 and 15 times the mass of Jupiter, there is a possibility that nuclear fusion is not happening. There is a new argument brought up by some astronomers that the formation of an object should factor into whether it can be a classified as a star or not, which is much more difficult to measure and determine. Brown dwarfs, and other stars as well, are formed due to the collapse of interstellar gas and dust. Planets on the other hand are thought to be formed as a disc of dust accretes into distinct bodies around a star. CFBDSIR 1458+10B is thought to be formed through the first process, and it is argued that it should subsequently be thought of as a star.

This candidate for the coldest star known is interesting in that it represents a potential shift in defining the lower mass limit for stars. What particularly excites me about this discovery, though, is not the change in classification that it might bring but that it is a new example of a type of object that we do not understand very well yet. This object lies very close to the boundary between a large gas giant planet and a brown dwarf star, and subsequently exhibits properties from both types of objects, especially in its atmosphere. Hot brown dwarf stars obtain their color mostly through the presence of sodium and potassium atoms in their atmospheres. In cooler brown dwarfs, and likely in an object like this one, it is expected that the sodium and potassium atoms join together into molecules, like potassium chloride, and are subsequently removed from the atmosphere. Due to this effect, their colors should be different. There is also the possibility of the presence of water clouds in the atmosphere, much more typical of gas giants. Regardless of whether or not this object is a star, it is undoubtedly very interesting.

Footnotes:

1: The name of the other object is CFBDSIR 1458+10A, and the name of the entire system is CFBDSIR 1458+10. Yes, astronomers are a witty bunch…↵
2: Even then, the low temperature would have placed it as the third coldest star known.↵

Kepler: An Evolution and a Shift

2011-02-19T23:59:00.000-08:00

The announcement by Kepler a little more than two weeks ago was undoubtedly huge. The discovery and confirmation of a really interesting planetary system consisting of six confirmed planets was released. This announcement was coupled with the discovery of over 1200 other planet candidates. In the time since the announcement, I have been struggling to fully comprehend the immense size of the numbers. Now, I have started to just realize that the numbers may not be the most interesting idea to keep in mind. We also have to step back from the recent news and see that the Kepler announcement may be the representation of the start of a new era and a giant shift in looking for life outside of the Earth.

At one level this Kepler announcement represents the evolution of our exoplanet detecting skills, and the number of planets discovered does tell a huge story. The rapid pace we have achieved in detecting exoplanets is no small feat. About 15 years ago, the first extrasolar planets, about the size of Jupiter, were just beginning to be detected. Before these discoveries, many scientists doubted ever being able to detect an extrasolar planet. Now, including great contributions being made by the Kepler spacecraft, we may have about 1500 planets detected and confirmed soon, a remarkable jump especially since many of these planets are much smaller than Jupiter. The Kepler announcement is also encouraging in that its discoveries are only being made in a single patch of sky. This area covers only about 1/400 of the area of the entire sky. Admittedly, other patches of the sky may not be as rich of stars containing planets as Kepler’s field of view, but it is extremely likely a huge amount of planets are still waiting to be discovered.

What really excites me though is that this announcement marks a shift in our search for extraterrestrial life. Although Kepler’s mission is to look for planets and not life, I feel that the scientific community and the rest of society is particularly interested in exoplanets because they may offer clues as to whether Earth life is an anomaly or the norm. This is why in every news piece I have read about the announcement so far, the fact about the list of potential Kepler candidates containing 54 planets about the size of the Earth located in the habitable zone is particularly emphasized. Any of these planets could contain life that is similar to ours and therefore their discovery captures our attention. The Kepler mission in particular represents a new era, in which our search for life outside our solar system is passing from a passive approach to a more active approach. In the era before Kepler, finding life outside of the solar system meant relying on projects such as SETI (Search for ExtraTerrestrial Intelligence). SETI attempts to detect signals that intelligent life may be broadcasting. This relies on the lifeforms having evolved and progressed as a society far enough so that they are able to regularly broadcast signals in the specific frequency ranges that Kepler is able to detect. Kepler, on the other hand, is taking a more active role. Kepler actually searches for planets that may be hospitable to life. Afterwards these planets can be examined in detail for traces of life, which do not necessarily have to be left behind by intelligent life.

The change, I think, is extremely important. Our search for life has become much more efficient and likely more fruitful. It as if we no longer have to face an expansive ocean hoping intensely that something in it will make contact with us. We can now wade in, start turning over rocks, and examine what we find. This is why I have been very obsessed and excited about the announcement. I believe when looking back after a number of years, the Kepler project and announcements like this will mark the point in history when we no longer sat back, but stood up and got our feet wet.

Kepler Discovers New Planetary System and Announces Over 1200 Planet Candidates

2011-02-11T18:50:00.000-08:00

The Kepler spacecraft started doing its work in May 2009, continuously watching the stars contained in a patch of sky with the hope of being able to discover exoplanets. Just recently, the Kepler team had a very exciting set of announcements resulting from this diligent work.

An artist’s conception of the Kepler-11 system.
Image: NASA/Tim Pyle

Comparison of Kepler-11 orbit sizes
and our Solar System’s orbit sizes.
Image: NASA/Tim Pyle

One of these was the discovery and confirmation of a newly found planetary system with six confirmed planets. Their star, Kepler-11, is a sun-like star, located about 2000 light years away from Earth. This star is only the second known so far to host multiple planets outside of our solar system, and now holds the record for hosting the most known planets. Plus, all of its planets have extremely tight orbits. The largest orbit is smaller than that of Venus in our solar system, while the other five orbits are even smaller than that of Mercury. This results in the most compact planetary system yet discovered in addition to the largest planetary system by number. Furthermore, the planets are bigger than the Earth, with the largest planet comparable to the size of Uranus and Neptune in our solar system. Still five of the six newfound planets are among the eight smallest extrasolar planets found so far. These interesting facts and characteristics of the system also lead to some clues about the formation and the dynamics of the system.

Kepler detects planets by measuring for drops in the light of their stars as they pass across, called the transit method (This method is detailed further in this previous post about Kepler). Measuring the changes in how much the light drops, at what times, and in what patterns can allow astronomers to calculate characteristics of the planet like size, distance from the star, and number of planets. Since the planets are located extremely close to each other in this particular system, five of the six planets produce significant perturbations on each others orbits that are measurable by Kepler. As they are detected, they will let the researchers calculate estimates for the masses of these planets. Further transits in the future will allow the estimates to be further refined. Adding this information with the sizes of the planets leads to the density of the planets that in turn could allow other researchers to hypothesize about the makeup of the planet. The densities of the planets in the Kepler-11 system appear low, suggesting that they are gaseous planets composed of light elements. These would be similar to planets like Neptune in our solar system rather than terrestrial planets like Earth. The conclusions also give suggestions about the formation of the planetary system. Presence of a large amount of light gas likely means that these planets were formed early in the history of their system. Finding out more about the formation of other planetary systems, such as this one, could, in turn, lead to valuable realizations about our own system.

Locations of Planet Candidates in Kepler FOV
Image: NASA/Wendy Stenzel

Yet, probably the more important announcement could be that in addition to these confirmed planets, Kepler has found over 1200 other planet candidates. These are discoveries that result in data that may be similar to that produced by the presence of an exoplanet, but needs to be verified and confirmed. The amount of actual planets from the list will almost definitely be less, but, more importantly, by how much? Some analyses are suggesting that about 80 to 90 percent of the objects on this preliminary list could be planets. This means that the amount of exoplanets discovered (currently about 530) could go up very significantly, by around 1000 (or about 200% of the current number) if the early analyses end up being accurate. Plus, in that preliminary list of planets, 54 are located in the habitable zone of their stars. This zone includes the orbits where a planet could potentially hold liquid water. The radius of one of these is about 0.9 times the size of the Earth’s, while the radii of four others are less than two Earth radii. A planet more Earth-like than any discovered so far may be among these data.

Results like this one are hugely important. They suggest the presence of the hundreds of other star systems, some unique systems like Kepler-11, or perhaps others also like our own solar system.

A Supermassive Black Hole in a Dwarf Galaxy

2011-01-10T22:55:00.000-08:00

A supermassive black hole exists in the center of our galaxy, with an incredible mass on the order of 4 million times that of the Sun. Our galaxy is not alone; most large galaxies also possess very large black holes as well. This leads to some interesting questions in galaxy formation and development: Which comes first, the black hole or the galaxy? Does a galaxy develop first, and then later, a massive black hole forms? Or does a black hole appear first, around which a galaxy much later forms? The discovery of a supermassive black hole could help answer that question.

A composite (X-ray, optical, and radio) image of the Henize 2-10 dwarf galaxy.
Image: X-Ray (NASA/CXC/Virginia/A. Reines et al);
Radio (NRAO/AUI/NSF); Optical (NASA/STScl)

Amy Reines, a graduate student, and her colleagues at the University of Virginia initially wanted to study the rapid star formation in the Henize 2-10 galaxy. The dwarf galaxy possesses many starburst regions and interesting newly formed super star clusters, where star formation has recently taken place. However, while looking back at the data, Reines and the researchers realized that there were signs of a black hole in the center of the galaxy. Radio radiation was originating at the spot, suggesting the presence of jets of radiation resulting from matter falling into the black hole. Further data from the Chandra X-ray Space Telescope revealed a high amount of X-ray radiation in the region, more evidence for the existence of a black hole.

Looking at black holes in the center of other galaxies has shown that there is a correlation with the mass of the central bulge in the galaxy and the mass of the black hole in the galaxy center. This has led some to speculate that a bulge in the galaxy was necessary for a black hole to form. The discovery of a black hole, with a mass about 2 million times that of the Sun, in Henize 2-10 challenges that notion. Henize 2-10 lacks a bulge, and being a dwarf galaxy, it has a low mass, only 10% of the Milky Way’s mass. It also has an irregular shape, with a rapid rate of star formation. These characteristics suggest that Henize 2-10 could be an early phase in the evolution of a galaxy and the answer to the above questions could be that black holes develop before galaxies form. With that though, we still have to keep in mind that the black hole in Henize 2-10 might be an outlier. Until we find more examples, the questions are still open.

2010 Going Into 2011

2011-01-01T10:59:00.000-08:00

Looking back, I have to say 2010 was a great year both for my blog and myself. I covered many interesting topics on my blog, including quite a few about exoplanets. Among other things this year, the Hubble celebrated its 20th birthday, the rover Spirit got stuck on Mars, and there is increasing evidence for an ocean on Mars. More personally, I started heavily using my binoculars, finished up my high school senior project on orbit determination, and started college this year.

I can’t yet say what I will write about in the coming year. This summer I decided to write some reflections about this blog, and I still feel that my purposes for this blog are evolving. I can’t predict exactly what kinds of things will be on my blog in the coming year. I also cannot predict all of the exciting discoveries that will undoubtedly be released this year. Right now, I just know that I can’t wait to start my first astrophysics class in college in this coming semester, and also share some exciting posts on this blog.

Happy new year everyone!

Book Review: Billions and Billions

2010-12-15T11:54:00.000-08:00

Image: Random House

I have to admit, I originally picked up Billions and Billions because of the title. Seeing it paired with Carl Sagan’s name instantly reminded me of Cosmos and his distinctive way of pronouncing billions. That initial statement and his personal explanation about it provided a wonderful introduction to the book, to what turned out to be an entry into the thoughts and beliefs of Carl Sagan.

What makes Billions and Billions distinctive is that it not only contains Sagan’s views on the cosmos, but other areas and issues about the world as well. Sure, the reader does ultimately learn more about what’s outside our planet through the book, but not without also seeing his views on areas such as climate change and nuclear weapons. Yet, perhaps as only Carl Sagan could, he compares these comparatively small issues with their importance on the grand scale. Never before have I been so deeply motivated to make more progress against climate change than after reading Sagan eloquently explain how we are gradually destroying life on the only place we know to harbor it in the universe.

The last parts of the book were especially moving. As someone viewing his writings from more than a decade past his death, it was somewhat painful to see how many future developments in science and technology he yearned to see, of which, some have since come to fruition, all the while remaining optimistic about humanity. Afterwards, I realized optimism was the one thing binding the book, and its myriad of topics, together. While discussing how humanity will face the problems of climate change or nuclear weapons, he never wavered from his optimism, continuously believing that we possess the necessary will and skill to tackle these future problems.

Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium is a wonderful book for anyone wishing to read thoughtful essays on current issues from a great scientist and astronomer, or even just wishing to learn more about Carl Sagan himself. This book is available at many online bookstores, including Amazon and Random House.

An Intriguing Planet From Outside the Galaxy

2010-11-26T23:34:00.000-08:00

An artist's impression of HIP 13044 and the planet HIP 13044 b.
Image: ESO/L. Calçada

Recently, exoplanets¹ have been discovered at an extremely rapid pace. In just about two decades, astronomers have found and confirmed over 500 planets, with many more waiting to be confirmed. Despite the large number, we're still finding a great amount of new things to be excited about in many of these discoveries.

The telescope used to make the discovery.
Image: ESO/H. H. Heyer

A newly announced exoplanet can claim to be the first one discovered to have originated outside our galaxy. Discovered by the Max Planck Institute in Germany using a 2.2m telescope at the European Southern Observatory in Chile, the planet, HIP 13044 b, orbits around a star, HIP 13044, that is located in the Helmi stream about 2,000 light years from the Sun. This particular group of stars originated from a small satellite galaxy of the Milky Way. The galaxy was later absorbed by the Milky Way about six to nine billion years ago, and gravitational tidal forces subsequently tore it apart and stretched it into a stream of stars. Both the star and planet orbiting around it were likely swept along for the ride.

This particular planet was discovered by the “wobble” method, just as many other exoplanets have been discovered in the past. The host star is studied for a long period of time, and a wobble, found for this star by a doppler shift, indicates a planet gravitationally tugging back on the star as it orbits around. The wobble in this particular case suggests a giant massive planet (similar to Jupiter) orbiting very closely to the star. This is very surprising, since the host star has also already passed through its red giant phase. When a Sun-like star enters the red giant phase, it grows extremely large, increasing its radius by ten to even hundreds of times larger that its original radius. Our Sun is expected to have a radius extending beyond the Earth's orbit when it becomes a red giant in around five billion years. However HIP 13044 b lies very close to its star, inside the area that was likely taken up by the star's red giant size before. This is likely due to the planet migrating inwards from a larger original orbit after the star shrunk, which is very intriguing. Later, the host star is expected to become an asymptotic giant branch² star, and the discoverers of the planet believe it will be devoured by the star at that time.

Furthermore, this exoplanet's host star is very metal-poor, meaning that it does not have many elements heavier than helium. Other exoplanets discovered so far, on the other hand, have had host stars that are at least as metallic as the Sun. HIP 13044, like the other stars in the Helmi stream, has metal content of about 1% of that of the Sun, in a mass that is about equal to the Sun's. This is just simply not a curiosity, but a potential reconsideration of how planets are formed. In the widely accepted core-accretion planet formation model, the matter around a star gradually coalesces to form planets. However, this model requires heavier elements to begin the process of planet formation, by forming the rocky core first. Without a rocky core, a gas giant, like this particular exoplanet, could not be formed since there is not enough mass to retain the gas. There is an alternative model for the formation of giant planets, called the disk instability , where a giant disk of gas around a star breaks off into planet-sized self-gravitating pieces. These pieces eventually each result in a giant planet. The model may be relevant in this case and this exoplanet discovery may provide substantial evidence for the disk instability model, or perhaps may lead to another future model.

HIP 13044 b's discovery continues to show that although exoplanet discoveries may no longer by novel in and of themselves, they still bring forth fresh considerations and interesting ideas.

Footnotes:

1: Short for extrasolar planets, which are planets located outside our solar system. ↵
2: In order to explain the asymptotic giant branch, I should explain the Hertzsprung-Russell (H-R) diagram first. The H-R diagram is essentially a scatter graph of stars plotted by their temperatures and luminosities (some use other related classifications like absolute magnitude, spectral types, etc.). Most stars in the H-R diagram lie on an area that looks like a curved line called the main sequence. There are also some branches that come out of the main sequence. The asymptotic giant branch is one of these branches, and consists of low to intermediate mass stars (about 0.6 to 10 times the mass of the Sun) in the late part of their stellar evolution. ↵

The Vehicle Assembly Building

2010-11-18T23:40:00.000-08:00

I just got 3D glasses today through Alan Boyle of CosmicLog, and I couldn't resist using a 3D video I had seen of the inside of NASA's Vehicle Assembly Building for my glasses’ first light¹. The Vehicle Assembly Building is one of the largest buildings on the planet, fourth by volume. The 3D video gives a great idea of the immense scale of the structure, with great views from the inside.

The Vehicle Assembly Building was originally constructed in order to assemble the components of the Saturn V rockets vertically. The building was large enough to contain four of the gargantuan rockets at a time, and includes four massive doors (the largest in the world) that each allowed the Saturn V to pass under. Nowadays, the Vehicle Assembly Building is used for the stacking of the space shuttle, combining vertically the orbiter, the solid rocket boosters, and the external fuel tank.

Rollout of Apollo 11
Image: NASA

STS-36 Rollout
Image: NASA

The duties of the VAB are not so clear once the space shuttle program is retired in 2011. Any future program that utilizes Launch Complex 39² will have access to it, however, none have been upon yet. One possible route could be the Orion Asteroid Mission, a modification of the Constellation program that would allow human exploration of an asteroid.

Footnotes:

1: Yes, technically this isn’t first light, since that’s generally a term used for the first astronomical images taken by an instrument. I extended the definition to encompass the first 3D images viewed through my glasses. ↵
2: The set of two launchpads and the Vehicle Assembly Building that was originally designed for the Apollo program and now used by the space shuttle program. ↵

Fly Around the Solar System

2010-11-13T01:24:00.000-08:00

Voyager 2 looking back at the planets in Eyes on the Solar System.

NASA’s new beta version of Eyes on the Solar System, developed by the Jet Propulsion Laboratory and Caltech, lets you do just that. The web application is essentially a 3D model of the solar system, containing many of its bodies and a great number of space probes sent out from Earth (including Epoxi 2, which recently performed a flyby of comet Hartley 2). With a number controls, you can zoom around the solar system exploring these objects, with beautiful 3D models for each of them. You can also manipulate the time to explore where the objects and the probes were in the past, or where they will be in the future.

Overall, this is a very glorious and well done project. It’s already a great tool for learning more about our planet's local neighborhood, and as it accumulates even more data and more components of the solar system, it can only get better. I can’t wait until this project leaves beta status, and includes further inclusions like nebulae and galaxies. You can head over to the project site right now to try it out. You will have to install the Unity Web Player plug-in in order to use it, and you will be prompted to install it on the site.

Cassini and Saturn in Eyes on the Solar System

Halley's Comet in Eyes on the Solar System

White Dwarfs as Pulsars

2010-10-14T18:18:00.000-07:00

A little more than two years ago, in early 2008, there was a shocking discovery from the Suzaku team. Suzaku is an orbiting X-ray observatory, operated jointly by JAXA and NASA. It had detected a white dwarf star, AE Aquarii, emit high-energy X-ray pulses. What’s more was that these pulses lined up exactly with the white dwarf’s spin period of 33 seconds. The star was behaving nearly like a pulsar.

Before I go into further discussion about white dwarfs acting like pulsars, I want to explain what the two types of stars are.

White Dwarfs

White dwarfs are essentially remains of stars that initially had a mass of less than about 8 solar masses (like the Sun). As these stars finish undergoing their fusion reactions, they form a carbon-oxygen core that cannot undergo fusion reactions, which is enveloped by a layer of helium fusion and a layer of hydrogen fusion. Ultimately, the outer layers are expelled, and the carbon-oxygen core remains. Therefore, the composition of most white dwarfs is carbon and oxygen.

These stars have a mass similar to that of the Sun, but a volume which is near the size of the Earth. Subsequently, white dwarfs have a very high density. White dwarfs also can have strong magnetic fields.

Furthermore, since their radius is greatly reduced from their original states, white dwarfs also have a very high angular velocity. This is a result of the conservation of most of the angular momentum of the original star. Conservation of angular momentum is often demonstrated by a spinning ice skater. As a spinning ice skater brings his/her arms in (comparable to the radius of the star shrinking), he/she starts spinning much faster. Therefore, as the star shrinks dramatically, its rotation increases greatly.

Pulsars

Larger stars, those with a mass greater than 8 solar masses, go a different route. In these stars, a growing iron core in the center of the star becomes so massive that it cannot support its own mass. The core collapses, creating neutrons and neutrinos as electrons are forced into the protons. This collapse results in an immense shockwave, which in turn causes the star itself to explode in what is called a supernova. The outer layers of the star are expelled in the supernova, leaving behind the remnants of the core of the star. This remaining star is very dense and very compressed, and is made up of mostly neutrons. These are called neutron stars.

The mass of a neutron star is typically not much greater than the mass of white dwarfs, usually between 1.35 and 2.1 solar masses. Their radius, on the other hand, is very small, just around 12 km. (In the case of very massive initial stars, the resulting neutron star is so massive that it further collapses into a black hole.) Therefore, their densities are extremely high. As Wikipedia states, it is comparable to the mass of the entire human population being squeezed into the size of a sugar cube.

In addition to their great density, neutron stars can also have a very large magnetic field. Plus, like white dwarfs, they conserve most of the angular momentum of their stars, so that when neutron stars form, they start spinning fast. They retains a very small fraction of the radius of the original star, so this results in an angular velocity which is much greater than that of a white dwarf. These two characteristics combine to create a pulsar.

The rotating magnetic field results in a powerful electric field forming on the star. This field accelerates protons and electrons on the surface of the star, and creates an electromagnetic beam which travels out from the magnetic poles of the star. The magnetic pole do not necessarily line up with the rotational axis of the star (just like the Earth’s magnetic poles do not correspond to the rotational axis of our planet), and as the star spins rapidly, the electromagnetic beam also spins around very rapidly. Sometimes, these beams can point in the direction of the Earth during their rotation, and when that happens, we can detect them as a pulsating source of emissions, resulting in the name pulsars (from pulsating stars). The period of the pulsation is the period of the rotation of the pulsar (ranging from 1.4 milliseconds to 8.5 seconds), and is very regular. In fact, the first pulsar discovered was temporarily dubbed LGM-1 for “Little Green Men,” since the discoverers considered extraterrestrial origins for the highly regular signal.

Eventually as energy is lost through the beam, the star slows down, and the pulsar mechanism turns off. This is expected to take place after around 10 to 100 million years.

White Dwarfs Acting Like Pulsars

White dwarfs and pulsars are often regarded as completely separate types of stars. That is why the discovery from the Suzaku team was so surprising. There were hard X-ray pulses which were being detected, and lining up exactly with the rotational period of the white dwarf star. The team had discovered a white dwarf star which was acting almost exactly like a pulsar.

This discovery has recently been brought back into focus because a recently published paper, led by Kazumi Kashiyama at Kyoto University, proposes a way for white dwarfs to act like pulsars.

This method could help explain the source of the high abundance of positrons in the range of 10 - 100 GeV, and of electrons and positrons in the range of 100 GeV - 1 TeV detected by the PAMELA spacecraft. Previously, a large number of objects were offered as the source of these particles, including pulsars. These, though, are expected not to result in the amount that has been detected by PAMELA. White dwarfs may however result in the amount of particles detected.

Typically, a white dwarf simply cannot reach a sufficient angular velocity to act like a pulsar. Their size during formation simply does not reduce as dramatically as it does for a neutron star. Kashiyama and others propose that in some cases, during a merger or accreting a large amount of mass from another star, can result in a greater angular velocity. Plus, about 10% of white dwarfs already are expected to have sufficiently powerful magnetic fields. Combining this magnetic field and sufficiently large angular velocity can result in a white dwarf behaving like a pulsar.

The proposition seems plausible since the idea of a white dwarf gaining mass is not very strange at all. This happens during the formation of a Type Ia supernova in binary star systems when a white dwarf gains mass from an accompanying star, or when two white dwarfs collide together. Furthermore, since white dwarfs have weaker magnetic fields, they would lose their energy slower, and keep spinning for a longer time. Subsequently, they can power the pulsar for a longer time, possibly accounting for the amount of particles detected by PAMELA. It also suggests that many of the pulsars that we observe in our own galaxy could in fact be white dwarf pulsars.

Next, it is necessary to provide conclusive evidence for the existence of such stars. AE Aquarii seems like a great candidate since it is a binary system, which could account for the white dwarf star accreting mass. In the meantime, this type of research, at least for me, is extremely exciting since it continues to show how the universe continues to surprise and amaze us.

New Exoplanet Could Be First Hospitable to Life

2010-10-04T00:04:00.000-07:00

An artist’s rendition of Gliese 581g.
Image: Copyright Lynette Cook

The first Earth-like exoplanet (a planet outside our Solar System has been discovered orbiting in a star’s habitable zone, a range of distances around a planet in which an Earth-like planet can keep and maintain liquid water. Essentially, this could mean that the planet may be hospitable to Earth-like life. The range is often referred to as the “Goldilocks zone” in that it is neither too hot nor too cold for life.

The existence of the planet, Gliese 581g, was recently announced by a team of astronomers from the University of California, Santa Cruz and the Carnegie Institute of Washington. The discovery used date from observations having been collected for over a decade at the Keck Observatory in Hawaii.

The Planet and Consequences for Life

Gliese 581g is one of two planets that was recently discovered orbiting Gliese 58, bringing the the total known planets orbiting the star to six. The star itself is located about 20 light years away from the Earth, and some of its other planets, lying on the edge of the habitable zone, have also been debated to be capable of harboring life. However, life on these planets would likely only be possible if these other planets had certain specific conditions, such as a very thick atmosphere in one case to result in a greenhouse effect that would sufficiently warm up the planet.

On the other hand, Gliese 581g lies very comfortably in the habitable zone. The planet itself is about three to four times the mass of the Earth. This mass likely means that the planet has a definite and rocky surface, and with enough gravity to hold on to an atmosphere. If its density is close to that of the Earth’s, the planet’s radius would be 1.2 to 1.4 times the size of the Earth’s. The gravity on the surface, therefore, would be similar to or slightly higher than on Earth.

Astronomers are estimating that the distance of Gliese 581g from its star is about 0.15 AU (1 AU is the distance from the Earth to the Sun), meaning that it can orbit around its star in a little less than 37 days. In our Solar System, this orbit would be even smaller than Mercury’s, and would make the planet severely hot. However, its star, Gliese 581, is classified as a red dwarf star, making it much cooler than our star, and at this radius, the average surface temperature on the planet is estimated to be between -31 to -12 °C.

This may be surprising in that this temperature is well below freezing, and likely not conducive to life as we know it. However, astronomers have been able to deduce that the planet is also tidally locked to the star. This means that there is one side continually facing the star while the opposing side is continually facing away from the star, just like how the Moon orbits the Earth (we only see one side of the Moon from the Earth). The consequence of this is that one side of Gliese 581g is in perpetual daylight and likely with a very high surface temperature. Meanwhile, the opposing side experiences the opposite treatment, receiving permanent nighttime and a low surface temperature. Life, could like likely only exist in a band between the light and the dark sides of the planet. This has some interesting consequences.

It is possible that lifeforms that prefer warmer temperatures could develop and exist on the brighter, warmer side of the planet, while those preferring a more colder and darker environment could live more towards the darker side. Plus differing longitudes on the planet could result in a wide range of hospitable temperatures. Therefore, despite the potential existence of just a narrow band of life, there could be very diverse ecosystems existing on the planet.

Method of Discovery

The discovery of Gliese 581g comes from 11 years of observations of the star Gliese 581. The team of astronomers working on this project used the HIRES spectrometer installed on the Keck I Telescope at the Keck Observatory in Hawaii. Using this tool, the astronomers were able to make very precise measurements of Gliese 581’s radial velocity. The radial velocity is the velocity of any object, including a star like Gliese 581, in the line of sight from Earth. As a planet orbits around its star, the star pulls on the planet gravitationally to keep it in orbit. The planet also pulls on the star, and this result in the star “wobbling” a little bit. The wobble can be detected from Earth by measuring the radial velocity of a star. Astronomers on Earth usually cannot actually see an exoplanet, but can detect changes in the radial velocity of the star. Studying this wobble allows astronomers to calculate the mass and distance from the star of the planet. Looking at the wobble over time allows astronomers to actually calculate the orbit of the planet.

If there are multiple planets, like in the case of Gliese 581, this technique gets a little more complicated. There is no longer just one pull from a planet, but multiple pulls. These gravitational pulls result in a combined complex wobble of the star. Performing analyses on this complex wobble, allows astronomers to detect the planets, and also calculate their orbits and masses.

This work however, requires many observations and measurements of radial velocity, spaced out over time. Detecting this particular planet took 238 observations, each of which lasted about an entire evening on the telescope.

Additional steps are helpful to verify that the wobble is in fact caused by orbiting planets. In some cases, stars may wobble due to processes within the star itself. In this study, a separate group of astronomers working with a robotic telescope at Tennessee State University made careful and precise measurements of the brightness of the star. This step gives important evidence that the radial velocity changes are likely caused by this orbiting planet, and not something else.

What does it mean?

The planet’s position in the habitable zone itself is a great discovery. Although it does not confirm the existence of life, this planet is the most likely to harbor life out of all exoplanets that have yet been discovered. Plus, the circumstances surrounding its discovery also yield stunning realizations.

The discovery has been made relatively quickly. There are only a small number of stars that have been studied by astronomers for the existence of exoplanets. This particular exoplanet has been discovered at a time when only a few Earth-like exoplanets have been discovered. Plus this discovery is very nearby, only about 20 light years away. Both these suggest that the existence of habitable Earth-like planets is in no way rare, as some believe. In our galaxy alone, the astronomers working on the project hypothesize, there could be tens of billions of star systems containing habitable Earth-like exoplanets, which is definitely a mind-blowing realization.

Flying through the Carina Nebula

2010-09-20T23:14:00.000-07:00

One of my favorite parts of the IMAX movie Hubble 3D was getting to fly through objects like the Orion Nebula in 3D. Often, when looking at objects in the night sky, I tend to forget that what I see is a complex three dimensional object of which I only get to see one side. Hubble 3D’s voyages through space provided a refreshing view in that it transformed those two dimensional pictures into three dimensional environments, a representation of what the actual objects may look like.

Using new and old images from the Hubble Telescope, the Hubble team has created a new three-dimensional virtual tour of the Carina Nebula, embedded above. Even though the tour is not completely based on solid scientific data and takes great artistic license, it is still breathtaking and inspiring. For me, it reminds me very powerfully of how dynamic, and in a way, tangible, the universe is.

In order to view the movie properly, you need red cyan anaglyphic glasses. If you don’t have the glasses (sadly I don’t either…) you can still enjoy the new image of the Carina Nebula recently released by the Hubble team below. It combines observations of radiation resulting from oxygen, captured this year, and that from hydrogen, captured in 2005.

The Carina Nebula, in Oxygen and Hydrogen Emissions
Image: NASA, ESA, Hubble Heritage Project

Equinox on Saturn

2010-09-06T19:47:00.000-07:00

About every 15 Earth years, Saturn’s experiences an equinox, much like Earth’s equinox. On Earth it occurs twice in Earth’s orbit—two times every Earth year—when the Sun lies in the Earth’s equatorial plane. As a result, the duration of day and night are approximately equal, which is also the origin of the term equinox.

Saturn also experiences this twice in its orbit, but its orbit lasts about 30 Earth years, meaning that the equinox takes place every 15 Earth years. Plus, this event is even more special on Saturn. Saturn has a very famous and widely recognized set of rings. These rings lie in Saturn’s equatorial plane, and therefore, when Saturn undergoes an equinox, the Sun also lies in the plane of the rings. Since the rings are very thin (at least compared to the size of Saturn), during the equinox the shadow from the rings disappears. The rings themselves also are barely visible because only the edges catch the light of the Sun.

The Cassini Spacecraft was present to capture photos from the most recent equinox last August. The below photograph was just recently released by the Jet Propulsion Laboratory, captured on July 18, 2009, just a few weeks before the equinox. The barely visible rings cast a thin shadow on the body of Saturn, creating a stunning view. In fact, the rings captured in the original images from Cassini were so dim that it was necessary to brighten them by a factor of 9.5 relative to the planet in order to produce the result (I’d be very interested to see the picture where the rings are not brightened).

The picture below is from just after equinox, when the shadow from the rings on Saturn is barely visible. Again, the brightness of the rings relative to the planet had to be increased in order to generate the image.

This equinox was also important in allowing Cassini to gather important data about the structure of the rings. When the rings are at a large angle to the Sun, small bumps and features are very hard to detect. However, when the Sun’s rays are parallel to the plain of the rings, the bumps and features create large shadows which are much easier to detect. And the results from this work were surprising. Some areas of Saturn’s rings ripple up and down, forming vertical formations about 800 km high. This phenomenon has not been explained yet. Meanwhile in some other areas, the particles in the ring are affected by the gravity of moons of Saturn, towering above the plain as high as 4 km. So while the rings may appear simple and peaceful in the images above, they have some very complex and strange features.

The Compass Project

2010-08-31T23:36:00.000-07:00

View of Sather Tower and the Moon
from Campbell Hall, Home of the
Berkeley Astronomy Department

I’m just starting my second week at the University of California, Berkeley as an intended Astrophysics and Physics major. But I wanted to talk about the two weeks before starting my first semester, when I got the opportunity to take part in the Compass Project.

The Compass Project is a two week summer program at UC Berkeley for incoming freshmen intending to major in the physical sciences. It is a pretty new program; this was only its fourth year. It is run and taught by graduate students in physics. Meeting and talking with graduate students about physics and what they do was a lot of fun. Through Compass, I also met a few other students who are also intending to major in the physical sciences. Like me, all 17 students are all very passionate about physics.

The best aspect of Compass, in my opinion, was the collaborative setting. At first, the classes were very overwhelming and strange. At all of my classes before, both in school and at a summer program I had attended the summer before, the teachers had essentially lectured the students. There was occasional collaboration, but not at an amount that I experienced at Compass. At Compass, the teachers merely posed questions, forcing us, the students, to work together in groups. We developed our own models and solutions to explain the physics behind wind turbines, argued amongst ourselves about the models, and made experiments to test our model’s predictions. Essentially, we were learning physics as physics is done, questioning our assumptions and working together to make our own discoveries and not by blindly accepting facts that professors or teachers may show us. This style of learning was mind-blowing to me. For example, I don’t think I can forget discovering why we can make certain assumptions in order to use the Continuity Law (A₁V₁ = A₂V₂).

The topic also lent itself to this type of work. Wind turbines were something that we were all familiar with, yet did not know much about. Most of us also understood some physics behind topics like pressure, fluids, and fluid density. However, the way these topics are taught in most high school physics classes glosses over the details and the development of the formulas and concepts. Topics like the kinetic energy density or, again, the assumptions used to develop the continuity model are often not explained thoroughly. We had to use our collective knowledge to completely understand these relationships.

As part of Compass, we even took numerous field trips both to help us learn more about wind turbines, and also visit local labs in the region. These places included, for example, the Altamont Pass Wind Farm (which is one of the oldest wind farms in United States), UC Berkeley’s Space Sciences Lab, and the Advanced Light Source. We also got the opportunity to tour some labs at UC Berkeley as well, like one studying nanotubes and another studying dark matter. I have put in some photographs from the field trips at the bottom of the post.

Because of Compass, I’m very excited for my next four years in studying physics at Berkeley. Compass has been one of the few times in my life that I have had the opportunity to learn physics in a way that it is actually done. Compass has also helped me realize more about the enormous number of frontiers that are being explored both in astrophysics and in physics. I know that by studying at Berkeley, I have a vast amount of opportunities to take part in that exploration.

Pictures from the Space Sciences Lab: (The first two pictures are of the home of Stardust@Home!)

Pictures from Altamont Pass Wind Farm:

Pictures from the Advanced Light Source:

Book Review: Endless Universe: Beyond the Big Bang

2010-08-06T19:31:00.000-07:00

Image: Michael J. Windsor,
Stewart Dickson, Doubleday

Challenging something so well established like the Big Bang Theory is no easy task. But Paul Steinhardt and Neil Turok have done exactly that, presenting a contender, called the Cyclic Theory, in their book Endless Universe: Beyond the Big Bang. The theory claims that there has been a violent event that took place 14 billion years ago, like the Big Bang model, but it was not the beginning of the universe. Instead, this event was just one of many like it that take place regularly. In the evolution of the universe, Steinhardt and Turok say, there has been, and there will be a “Big Bang” about every trillion years. According to the theory, we live in just one of these cycles defined by the violent events.

One of the biggest reasons why this new theory is particularly appealing is a result of the nature of its competition. The Big Bang Theory has been heavily modified over its long history in order to match what we see in the universe. What started as something simple and appealing has grown into somewhat of a monstrous patchwork. Plus, the Big Bang Theory leaves unexplained how the violent event could be the beginning of the universe. The Cyclic Theory, in comparison, is much simpler and, as the two physicists repeatedly claim, fits current observations just as well as the Big Bang Theory.

This is why I found Endless Universe so interesting. The theory is very unique and refreshing, and the evidence that it uses to support its claims seem very sound. Although the book involves a few confusing topics that are foreign to most people, like the concept of branes, the authors explain these very well in a manner most common people can easily understand. The authors also include their personal stories in developing their model, explaining their motivations for a new revolutionary theory, which lend further to the support of the Cyclic Theory.

After finishing the book, I cannot say for sure if the Cyclic Theory is correct. In fact, the true answer can only come as more observations are performed, in areas like the study of gravitational waves. Either or both of the Big Bang and Cyclic Theories can be easily eliminated in a quick sweep with just one decisive new finding.

Still, there is great value in reading the book since it exemplifies the true nature of science, the continual quest to find a simple and true way to explain nature. It is an integral part of one of the most interesting times in cosmology, when we are presented with several plausible competing theories which all have great implications about the nature of the universe.

Hunting for Ceres in the Pipe Nebula

2010-07-30T09:18:00.001-07:00

Ceres is the largest asteroid in the solar system, and is usually bright enough to be visible with telescopes and even binoculars (at around a magnitude of 7). However, unlike the brighter planets, it is not so bright to be able to be distinguishable from the stars that may surround it. Normally to do that would require taking multiple exposures of the field to see which one of the dot moves¹, or at the very least, looking at charts giving its position in relation to other stars. However in the month of July, due to its special position, identifying became a lot easier.

In July, Ceres passed in front of Barnard 78 (or the Pipe Nebula), a nebula in the Ophiuchus constellation made up of dark dust and gas. This opportune position allows the nebula to block out background stars which may be confused for the asteroid. Since Ceres is in our solar system, it isn't blocked out, allowing it to be made out easily.

When I observed Ceres on July 20 with my 15x70 binoculars, it took me just a few minutes to identify which dot was Ceres. If you have binoculars or a telescope, definitely try and go outside to see this asteroid. This special position won't last for long!

When hunting for the asteroid, using a chart from a computer is immensely helpful. I used charts from the iPhone/iPad app SkyVoyager and the July issue of Astronomy magazine.

Footnotes

1: Since the Earth rotates, stars rise in the east, move across the sky, and set in the west, just like the Sun. Asteroids (and also planets) also move in their orbits, so in addition to rising and setting, they move across the sky not following the other stars [this is why the name planet comes from the Greek work “wanderer”]. When taking multiple exposures and aligning the stars in the pictures, the one that moves is the asteroid, since it is not following the movement of the stars.

A Planet with a Tail

2010-07-26T09:23:00.001-07:00

An artist's interpretation of how extrasolar planet HD 209458b may look.
Image: NASA, ESA, and G. Bacon (STScL)

A giant gas extrasolar planet, HD 209458b, has recently been confirmed to possess a tail, resembling something like that of a comet. The planet is similar to Jupiter, but unlike Jupiter it orbits very close to its star, completing an orbit every 3.5 days¹.

The planet, about 153 light-years from Earth, has been heavily studied since its initial discovery because it was one of the first discoveries of an extrasolar planet transiting its star. This is a special case where the orbit of the planet allows it to eclipse its star, as seen from the Earth. The rare position essentially allows astronomers to study the atmosphere of the planet, finding out what chemicals make it up (the process is detailed for a similar case here). Astronomers studying HD 209458b discovered that the planet’s atmosphere contains heavy elements including carbon and silicon. Since the atmosphere is exposed to the scorching heat of the star due to their close proximity, the heavy elements can escape.

Eventually, these materials come together to form a large flow of gas coming out from the planet. On the Earth, astronomers have detected the gas to be coming towards us at 22,000 miles per hour. When the stellar wind from the star picks up the gas, the tail, resembling one of a comet’s, is formed. Still, despite the large outflow of gas, the planet is not likely to completely “evaporate” anytime soon. It is estimated that it will take a trillion years for that to happen.

The recent finding is important in that it further helps us realize how our star is not unique in harboring planets, as the numerous other discoveries of extrasolar planets have proved. However, perhaps more importantly, it shows the intense variety of what can be found in the universe.

Footnotes

1: Extrasolar planets are planets that are found outside of our solar system, orbiting other planets. Recently, there has been an explosion in the discovery of extrasolar planets, and the number of total extrasolar planets discovered so far is currently a little over 450.

Reading List

2010-07-15T21:20:00.001-07:00

Some of what I have been reading this week, both online and offline:

Felix Baumgartner is planning on skydiving from the edge of space, at 120,000 feet above the ground. Aside from setting a new record, the jump could help develop and perfect technologies for escape systems on space vehicles, like the Space Shuttle, or future commercial space transport. [Read at SPACE.com]
A picture of the July 11 solar eclipse visible during sunset from the Andes mountains. The eclipse was viewable in southern areas of South America and the Pacific Ocean. [See and read about the picture at APOD]
In addition to the book Endless Universe, I’ve also started to read Einstein’s Telescope. The author, Evalyn Gates, discusses the presence of dark matter and dark energy. It is an interesting read so far since Gates presents the difficult topic with a good amount of explanation and also humor.

Adventures with Binoculars: Using a Tripod

2010-07-14T16:16:00.000-07:00

After initially getting my binoculars, I was very excited to be able to get out quickly and start observing. However, after a few short observing sessions, holding the binoculars in my unstable hands, I started to notice that my views were getting shaky. I have a pair of 15x70 binoculars (meaning they have a 70 mm or 7 cm aperture, which is the size of the objective). This is great because it captures a lot of light and can more easily reveal darker objects. But, that huge aperture also comes with the downside of a fairly large size and weight. As I talked about in my review, they can be usable handheld for short periods of time, but detailed observations lasting longer than about a minute or two can’t be done.

So the time came to start using a tripod. Luckily, the Celestron Skymaster 15x70 binoculars that I have came with a tripod adapter. When researching to buy a pair of binoculars, I did find that most other similar binoculars (in size and price) also come with a tripod adapter. This tripod adapter (pictured) allows an easy attachment of the binoculars to a standard tripod, often used for photography. The whole assembly, with the tripod and the binoculars, can be done in just a few minutes, still allowing that short setup time characteristic of binoculars.

And the tripod has made such a big difference for my observations. Before I used to go outside for casual observing, just to sit down and try to quickly view and identify as many objects in the night sky as possible. Now, most of my observations are much more detailed. I can try to focus on more trickier targets and let myself absorb all the small details that casual observing did not allow. This small change has made a huge difference in my observing habits with binoculars, and it is absolutely necessary to do more detailed observations with powerful binoculars.

Adventures with Binoculars is a new series of posts I'm starting which documents my observations and experiences with my binoculars. For a review of the binoculars I am using, see this earlier post.

Rosetta's Closeup with Asteroid Lutetia

2010-07-12T20:17:00.000-07:00

Asteroid Lutetia, captured by Rosetta
Image: ESA

ESA’s Rosetta mission successfully completed a flyby of asteroid Lutetia on July 10, capturing spectacular images of a remnant from the solar system’s creation. The spacecraft came as close as 3162 km, at a velocity of 15 km/s. At that velocity, the flyby did not last long (about a minute), but the craft was prepared with a variety of sensors to capture data before, during, and after the short flyby. Rosetta hunted for evidence of the presence of an atmosphere and magnetic effects, while studying the composition and density of the rocky body. The spacecraft even tried to capture and analyze grains of dust from the asteroid that may have been kicked into space around the asteroid. The results from these studies will be revealed at a later time.

Probably the most breathtaking of the rich information the Rosetta spacecraft captured from its flyby are the magnificent images of the rocky body. The craters and the surface of the asteroid are revealed in a stunning amount of detail, never before available to us. The images were especially breathtaking for me since I worked on researching asteroids for my high school senior project. Looking at just a tiny dot moving across a computer screen, I could never help but wonder what that tiny dot really is. What does it actually look like and what is it made of? Now looking at any asteroid, at what on Earth would appear as just a small dot indistinguishable from the hundreds of stars on an image, take on a definite and unique shape never ceases to blow me away.

Asteroid Lutetia with Saturn
Image: ESA

My favorite image from Rosetta is the image of asteroid Lutetia captured alongside Saturn. It nicely frames one of the largest bodies in the solar system with one of the smallest.

The Rosetta mission itself was launched in 2004, and is headed towards comet 67P/Churyumov-Gerasimenko, with that encounter scheduled for 2014. It will orbit the comet and deploy a lander, studying its composition which will help us eventually understand more about comets and the early solar system. In fact, Rosetta’s name originates from that of the Rosetta Stone, since it is designed to unlock secrets about the solar system before the existence of planets, much like how the Rosetta Stone unlocked secrets about Egyptian hieroglyphics. Asteroid Lutetia is the second asteroid that the spacecraft has flown by on its way to the comet.

Additional images of Lutetia captured by Rosetta are included below. (Images: ESA)

P.S. This is my blog’s 100th post. Wow.

The Pale Blue Dot

2010-06-27T20:46:00.005-07:00

The Pale Blue Dot
Image: NASA

In 1990, after having completed its primary mission, Voyager 1 received instructions to turn its cameras back around to Earth. NASA had received a request from the famous astronomer Carl Sagan to photograph the Earth from 6 billion kilometers away, as the spacecraft was leaving the Solar System. In the resulting picture (above), Earth appeared to be just a tiny dot hanging in a beam of light in the middle of space, a "pale blue dot."

Carl Sagan's reflections about the picture are especially thought provoking and humbling. His words never fail to make me appreciate the value of humanity and our home planet.

From this distant vantage point, the Earth might not seem of particular interest. But for us, it's different. Consider again that dot. That's here, that's home, that's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

Carl Sagan later wrote The Pale Blue Dot: A Vision of the Human Future in Space*. Inspired by the photograph, Carl Sagan talked about the human future in space. Recently director Michael Marantz has constructed a wonderful short film based on an excerpt from the book. You can watch it below. (It looks great full screen in HD!)

Update: I found another great video on YouTube. This one is based on the based on the reflection written above.

*The book is available on Amazon, and is a great read. Please note that purchases made on Amazon.com through Amazon links on this blog help support this blog. A small portion of your purchase will automatically be donated towards this blog. You will not be charged extra for your purchase.

Reading List

2010-06-22T22:28:00.000-07:00

Some of what I have been reading recently:

This article discusses proper motion, the movement of a star in the sky due to its movements in space or even due to the movements of the Sun itself. It uses Barnard's Star as an example, which is located just 6 light years away and has a proper motion of 10 arcseconds a year! The article includes the change in the position of Barnard's Star over 60 years, from 1950 to 2010. [Read at Bad Astronomy]
John Glenn, first American in orbit, wants the space shuttle to remain operational. [Read at Space.com]
Wonderful image of a star forming region made up of gas in the Large Magellanic Cloud taken by the Hubble Space Telescope. [Read at Space Fellowship]
There are low levels of uranium on the lunar surface. This may help reveal vital information about the formation of the Moon's surface (and also rules out ideas of futuristic moon missions that could rely on uranium for energy or commercial uses). [Read at Space.com]
I've also been reading the book Endless Universe: Beyond the Big Bang by Paul Steinhardt and Neil Turok. The book critiques the Big Bang theory and presents potential flaws in the inflationary model, while proposing the "Cyclic Universe" theory. I plan to post a full review once I finish reading. [Available at Amazon.com]

Please note that purchases made on Amazon.com through Amazon links on this blog help support this blog. A small portion of your purchase will automatically be donated towards this blog. You will not be charged extra for your purchase.

Tracing Saturn

2010-06-19T19:49:00.000-07:00

Image: NASA/JPL/Space Science Institute

Looking at this picture just blew me away. It is so simple, yet is able to reveal Saturn's unique shape immediately.

The picture was taken by the Cassini spacecraft, currently orbiting Saturn, on February 13, 2010, with the sun located behind Saturn. Saturn's outline is created by scattered sunlight passing through Saturn's upper atmosphere. Some of this light is eventually captured by the cameras aboard Cassini. Near the bottom of the picture, the rings are visible since the picture is taken with Cassini located above the plane of the rings.

An Ocean on Mars

2010-06-16T22:04:00.000-07:00

An illustration of the probable size and location of the ocean on Mars.
Image: University of Colorado

There has been a large and increasing amount of evidence for the past presence of liquid water on Mars, perhaps even in large quantities. However, recently, a new study conducted by scientists at the University of Colorado at Boulder suggests that there was a large ocean, stretching across a third of the Martian surface, about 3.5 billion years ago.

Previously, many scientists have speculated and used several pieces of evidence to suggest that oceans have existed on Mars. But the idea has also been challenged and questioned many times. New research conducted by Gaetano Di Achille and Brian Hynek is giving more proof for the previous existence of an ocean.

The scientists' findings show that 29 of the 52 deltas that they investigated were situated at about the same level 3.5 billion years ago, suggesting that they were part of the same body of water. These deltas probably created the border, or the shoreline, of an entire ocean in the northern part of Mars. Di Achille and Hynek were the first to integrate the various sets of data collected from NASA and ESA's missions orbiting around Mars. Some of the data dates back to 2001.

The ocean that Di Achille and Hynek generated from their research using a Geographic Information System (GIS) covered about 36 percent of the planet, containing about 124 million cubic kilometers (or 30 million cubic miles) of water. This much water would be enough to create a layer of water 550 meter (1800 foot) deep across the entire Martian surface! The ocean would have contained about 10 times less water than the entire volume of the Earth's oceans, while the area covered would be larger than that of the Atlantic Ocean.

Furthermore, an additional study conducted at the University of Colorado at Boulder detected about 40,000 river valleys on Mars, about 4 times the number previously identified. Combining the results of he two studies paints an exciting picture of what existed on Mars. The river valleys were the source for the sediment that was eventually dumped into the deltas. And putting together the extremely large number of river valleys, the river deltas, and the large ocean, suggests that there probably was a global water cycle earlier in Martian history, similar to what exists on planet Earth today.

This research also leaves very intriguing implications for the presence of life on Mars. On our own planet, where there is a large abundance of life, oceans provide a nurturing environment for life and river deltas readily embed signs of it, like organic carbon. For future missions to the surface of the red planet, deltas may prove very valuable targets for hints about past life.

So at this stage, the obvious question is, where did the water go? A study from a few years ago suggested that the disappearance may be due to solar flares and the solar wind. Since Mars is a lot smaller than the Earth, its molten core probably cooled down quickly, resulting in the planet to lose its global magnetic field. In fact, the red planet currently does not have a magnetosphere. On the Earth, a magnetosphere helps protect the atmosphere from the harmful effects of the solar wind, solar flares, and high-energy particles. Without the protection, the Martian atmosphere is vulnerable, and over time most of the Martian atmosphere has been lost. Right now, due to the very low atmospheric pressure on Mars, liquid water cannot exist on the Martian surface (with the exception being the lowest elevations, and even then for extremely short periods).

A combination of findings and research is now helping depict the entire history of water on Mars. From the large ocean, to the dry place it is today. Yet, the story is not complete, and what we know only makes up small chunks of the entire story. A lot is still changing and added on to what we know about the red planet's relationship with liquid water.