Earth Blog

Jupiter's north pole seen by Juno spacecraft

2018-03-24T00:15:00.006+00:00

In this composite image, derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA's Juno mission to Jupiter, shows the central cyclone at the planet's north pole and the eight cyclones that encircle it. JIRAM collects data in infrared, and the colors in this composite represent radiant heat: the yellow (thinner) clouds are about 9 degrees Fahrenheit (-13° Celsius) in brightness temperature and the dark red (thickest) are around -181 degrees Fahrenheit (-118.33° Celsius).

Image Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA22335

Exoplanet WASP-39b

2018-03-22T22:23:00.001+00:00

An international team of scientists has used the NASA/ESA Hubble Space Telescope to study the atmosphere of the hot exoplanet WASP-39b. By combining this new data with older data they created the most complete study yet of an exoplanet atmosphere. The atmospheric composition of WASP-39b hints that the formation processes of exoplanets can be very different from those of our own Solar System giants.

Investigating exoplanet atmospheres can provide new insight into how and where planets form around a star.“We need to look outward to help us understand our own Solar System,” explains lead investigator Hannah Wakeford from the University of Exeter in the UK and the Space Telescope Science Institute in the USA.

Therefore the British-American team combined the capabilities of the NASA/ESA Hubble Space Telescope with those of other ground- and space-based telescopes for a detailed study of the exoplanet WASP-39b. They have produced the most complete spectrum of an exoplanet’s atmosphere possible with present-day technology.

WASP-39b is orbiting a Sun-like star, about 700 light-years from Earth. The exoplanet is classified as a “Hot-Saturn”, reflecting both its mass being similar to the planet Saturn in our own Solar System and its proximity to its parent star. This study found that the two planets, despite having a similar mass, are profoundly different in many ways. Not only is WASP-39b not known to have a ring system, it also has a puffy atmosphere that is free of high-altitude clouds. This characteristic allowed Hubble to peer deep into its atmosphere.

By dissecting starlight filtering through the planet’s atmosphere the team found clear evidence for atmospheric water vapour. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers had predicted they would see water vapour, they were surprised by the amount that they found. This surprise allowed to infer the presence of large amount of heavier elements in the atmosphere. This in turn suggests that the planet was bombarded by a lot of icy material which gathered in its atmosphere. This kind of bombardment would only be possible if WASP-39b formed much further away from its host star than it is right now.

“WASP-39b shows exoplanets are full of surprises and can have very different compositions than those of our Solar System,” says co-author David Sing from the University of Exeter, UK.

The analysis of the atmospheric composition and the current position of the planet indicate that WASP-39b most likely underwent an interesting inward migration, making an epic journey across its planetary system. “Exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that’s fantastic!”, adds Wakeford.

Having made its incredible inward journey WASP-39b is now eight times closer to its parent star, WASP-39, than Mercury is to the Sun and it takes only four days to complete an orbit. The planet is also tidally locked, meaning it always shows the same side to its star. Wakeford and her team measured the temperature of WASP-39b to be a scorching 750 degrees Celsius. Although only one side of the planet faces its parent star, powerful winds transport heat from the bright side around the planet, keeping the dark side almost as hot.

“Hopefully this diversity we see in exoplanets will help us figure out all the different ways a planet can form and evolve,”explains David Sing.

Looking ahead, the team wants to use the NASA/ESA/CSA James Webb Space Telescope — scheduled to launch in 2019 — to capture an even more complete spectrum of the atmosphere of WASP-39b. James Webb will be able to collect data about the planet’s atmospheric carbon, which absorbs light of longer wavelengths than Hubble can see. Wakeford concludes: “By calculating the amount of carbon and oxygen in the atmosphere, we can learn even more about where and how this planet formed.”

Image Credit: NASA, ESA, and G. Bacon (STScI)
Explanation from: https://www.spacetelescope.org/news/heic1804/

Mount Sinabung Volcano Eruption

2018-03-21T08:32:00.001+00:00

Berastagi, Sumatra, Indonesia

February 19, 2018

Image Credit: Reuters

Dwarf Galaxy IC 4710

2018-02-28T19:47:00.001+00:00

Discovered in 1900 by astronomer DeLisle Stewart and here imaged by the NASA/ESA Hubble Space Telescope, IC 4710 is an undeniably spectacular sight. The galaxy is a busy cloud of bright stars, with bright pockets — marking bursts of new star formation — scattered around its edges.

IC 4710 is a dwarf irregular galaxy. As the name suggests, such galaxies are irregular and chaotic in appearance, lacking central bulges and spiral arms — they are distinctly different from spirals or ellipticals. It is thought that irregular galaxies may once have been spirals or ellipticals, but became distorted over time through external gravitational forces during interactions or mergers with other galaxies. Dwarf irregulars in particular are important to our overall understanding of galactic evolution, as they are thought to be similar to the first galaxies that formed in the Universe.

IC 4710 lies roughly 25 million light-years away in the southern constellation of Pavo (The Peacock). This constellation is located in the southern skies and also contains the third-brightest globular cluster in the sky, NGC 6752, the spiral galaxy NGC 6744, and six known planetary systems (including HD 181433 which is host to a super-Earth).

The data used to create this image were gathered by Hubble’s Advanced Camera for Surveys (ACS).

Image Credit: ESA/Hubble, NASA, Judy Schmidt
Explanation from: https://www.spacetelescope.org/images/potw1809a/

Hawaii seen from the International Space Station

2018-02-27T17:42:00.003+00:00

Crews aboard the International Space Station oriented the camera specifically to capture this panorama of Hawaii's Kilauea volcano (image left) with the long swirls of volcanic gases (top half of the image) wafting west from the volcano. Astronauts are trained to take oblique images of hard-to-see atmospheric haze by shooting obliquely to enhance visibility. The gas haze--termed vog, a combination of fog, smog and volcanic--is well known in Hawai'i, and is defined as "a form of air pollution that results when sulfur dioxide and other gases ... emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight".

Here the vog haze is transported hundreds of km downwind of the volcano (for scale the Big Island is 137 km, 85 miles, long). In this unusual view the vog forms a series of subtle but distinct alternating swirls (arrows) known as von Karman vortices, a favorite topic for crew photography. Swirls form under specific conditions of high atmospheric pressure and relatively slow wind speeds. They usually develop in clouds downwind of islands, as shown in many astronaut images of cloud patterns. Images of vog haze are captured often by astronauts, but few show the swirl phenomenon.

Image Credit: NASA
Explanation from: https://eol.jsc.nasa.gov/SearchPhotos/photo.pl?mission=ISS042&roll=E&frame=281151

Protoplanetary Disk AS 209

2018-02-26T17:07:00.004+00:00

Nestled in the young Ophiuchus star-forming region, 410 light-years from the Sun, a fascinating protoplanetary disc named AS 209 is slowly being carved into shape. This wonderful image was captured using the high-resolution ALMA telescope, revealing a curious pattern of rings and gaps in the dust surrounding a young star.

Protoplanetary discs are dense, rotating planes of gas and dust that surround newly formed stars; providing the matter that one day becomes orbiting planets, moons and other minor bodies. At less than one million years old, this system is very young, but already two clear gaps are being sculpted from the disc.

The outer gap is deep, wide, and largely a dust-free zone, leading astronomers to believe that a giant planet almost the mass of Saturn is orbiting here — around 800 light-minutes from the central star, and more than three times the distance between Neptune and the Sun! As the planet carves out its path, dust piles up at the outer edge of its orbit, creating ever more defined rings in the disc. The thinner, inner dust gap could have been formed by a smaller planet, but astronomers have raised the intriguing possibility that the large and distant circling planet in fact created both paths.

This inferred Saturn-like planet so far from its central star raises fascinating questions about planet formation at the edges of protoplanetary discs on particularly short timescales.

Image Credit: ALMA (ESO/NAOJ/NRAO)/ D. Fedele et al.
Explanation from: https://www.eso.org/public/images/potw1809a/

Spiral Galaxy NGC 3344

2018-02-15T14:52:00.002+00:00

Captured by the NASA/ESA Hubble Space Telescope, the galaxy NGC 3344 presents itself face-on, allowing astronomers a detailed look at its intricate and elegant structure. And Hubble’s ability to observe objects over a wide range of different wavelengths reveals features that would otherwise remain invisible.

Spiral galaxies are some of the most spectacular sights in the sky, but to an observer they do not all look the same. Some are seen edge-on, giving astronomers an excellent idea of the galaxy’s vertical structure; others are seen at an angle, providing a hint of the size and structure of the spiral arms; while others are seen face-on, showcasing their arms and bright core in all their beauty.

Approximately 20 million light-years away in the constellation of Leo Minor (the Lion Cub), NGC 3344 is seen from a breathtaking face-on perspective. Half the size of the Milky Way, it is classified as a weakly barred spiral galaxy. The central bar is just visible in this image, taken with Hubble’s Wide Field Camera 3: an elongated lane of stars, trailing through the nucleus of the galaxy. Astronomers estimate that two-thirds of all spiral galaxies are barred, including our own Milky Way.

Hubble’s capacity to observe celestial objects in different wavelengths allows us to see more than just the spiral arms sweeping out loosely around the centre in a gorgeous whorl. This image is a composite of images taken through different filters, ranging from the near ultraviolet, to the optical and the near-infrared. Together they show a more complete picture of the galaxy than the human eye alone could possibly see.

The swirling spiral arms are the birthplace of new stars, whose high temperatures make them shine blue, resulting in them being easily identifiable in this image. Clouds of dust and gas distributed through the spiral arms — glowing red in this image — are reservoirs of material for even more stars. The bright jewel-like stars on the left of the picture, however, are much closer to Earth — they belong to our own galaxy and just happened to photobomb this Hubble image.

While its face-on orientation reveals much about NGC 3344’s detailed structure, this galaxy is still enigmatic; astronomers have noticed that some of its outer stars are moving in a strange way. Often, the high concentration of stars in the centre of a galaxy can affect the movements of the outer stars, but this does not seem to be the case in NGC 3344. Astronomers suspect that these weirdly behaving outer stars may actually have been stolen from another galaxy, after a close encounter that took place long ago.

The location of NGC 3344 is also intriguing. Our galaxy is part of the Local Group, which is made up of approximately 40 other galaxies, with the Andromeda Galaxy being the largest member. But NGC 3344 is not part of a local galactic neighbourhood like we are. It is actually part of a small spur that leads off the larger Virgo Supercluster — a gargantuan collection of several thousand galaxies.

But it stands out from these thousands of galaxies because of its beauty, which highlights to us the elegance of the Universe.

Image Credit: ESA/Hubble, NASA
Explanation from: https://www.spacetelescope.org/news/heic1803/

Earth and Moon seen by OSIRIS-REx spacecraft from 63 million kilometers away

2018-02-14T18:52:00.003+00:00

As part of an engineering test, NASA’s OSIRIS-REx spacecraft captured this image of the Earth and Moon using its NavCam1 imager on January 17 from a distance of 39.5 million miles (63.6 million km). When the camera acquired the image, the spacecraft was moving away from home at a speed of 19,000 miles per hour (8.5 kilometers per second).

Earth is the largest, brightest spot in the center of the image, with the smaller, dimmer Moon appearing to the right. Several constellations are also visible in the surrounding space. The bright cluster of stars in the upper left corner is the Pleiades in the Taurus constellation. Hamal, the brightest star in Aries, is located in the upper right corner of the image. The Earth-Moon system is centered in the middle of five stars comprising the head of Cetus the Whale.

NavCam1, a grayscale imager, is part of the TAGCAMS (Touch-And-Go Camera System) navigation camera suite. Malin Space Science Systems designed, built, and tested TAGCAMS; Lockheed Martin integrated TAGCAMS to the OSIRIS-REx spacecraft and operates TAGCAMS.

Image Credit: NASA/Goddard/University of Arizona/Lockheed Martin
Explanation from: https://www.nasa.gov/image-feature/goddard/2018/osiris-rex-captures-new-earth-moon-image

The Nile at Night seen from the International Space Station

2018-02-13T18:15:00.001+00:00

September 22, 2015

Image Credit: NASA

R Sculptoris

2018-02-12T17:10:00.004+00:00

This ghostly image features a distant and pulsating red giant star known as R Sculptoris. Situated 1200 light-years away in the constellation of Sculptor, R Sculptoris is something known as a carbon-rich asymptotic giant branch (AGB) star, meaning that it is nearing the end of its life. At this stage, low- and intermediate-mass stars cool off, create extended atmospheres, and lose a lot of their mass — they are on their way to becoming spectacular planetary nebulae.

While the basics of this mass-loss process are understood, astronomers are still investigating how it begins near the surface of the star. The amount of mass lost by a star actually has huge implications for its stellar evolution, altering its future, and leading to different types of planetary nebulae. As AGB stars end their lives as planetary nebulae, they produce a vast range of elements — including 50% of elements heavier than iron — which are then released into the Universe and used to make new stars, planets, moons, and eventually the building blocks of life.

One particularly intriguing feature of R Sculptoris is its dominant bright spot, which looks to be two or three times brighter than the other regions. The astronomers that captured this wonderful image, using ESO’s Very Large Telescope Interferometer (VLTI), have concluded that R Sculptoris is surrounded by giant “clumps” of stellar dust that are peeling away from the shedding star. This bright spot is, in fact, a region around the star with little to no dust, allowing us to look deeper into the stellar surface.

This image captures an extremely small section of the sky: approximately 20x20 milliarcseconds. For comparison, Jupiter has an angular size of approximately 40 arcseconds.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/potw1807a/

Spiral Galaxy NGC 1559

2018-02-11T19:04:00.003+00:00

Roughly 50 million light-years away lies a somewhat overlooked little galaxy named NGC 1559. Pictured here by Hubble’s Wide Field Camera 3, this barred spiral lies in the little-observed southern constellation of Reticulum (The Reticule).

NGC 1559 has massive spiral arms chock-full of star formation, and is receding from us at a speed of about 1300 km/s. The galaxy contains the mass of around ten billion Suns — while this may sound like a lot, that is almost 100 times less massive than the Milky Way. Although NGC 1559 appears to sit near one of our nearest neighbours in the sky — the Large Magellanic Cloud (LMC), this is just a trick of perspective. In reality, NGC 1559 is physically nowhere near the LMC in space — in fact, it truly is a loner, lacking the company of any nearby galaxies or membership of any galaxy cluster.

Despite its lack of cosmic companions, when this lonely galaxy has a telescope pointed in its direction, it puts on quite a show! NGC 1559 has hosted a variety of spectacular exploding stars called supernovae, four of which we have observed — in 1984, 1986, 2005, and 2009 (SN 1984J, 1986L, 2005df [a Type Ia], and 2009ib [a Type II-P, with an unusually long plateau]).

NGC 1559 may be alone in space, but we are watching and admiring from far away.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1806a/

Storm and Lightning over Petrified Forest National Park

2018-02-10T23:52:00.000+00:00

Navajo, Arizona

Image Credit: Ralph Lauer, ZUMA Press/Corbis

Spotless Sun

2018-02-09T16:42:00.006+00:00

The Sun has had no sunspots for almost two weeks (as of February 1, 2018) and just has a single, tiny one that appeared on January 31, 2018. This spotless period is a prelude to the approaching period of solar minimum next year, when the Sun's activity will be at the low end of its 11-year cycle.

Image Credit: NASA/GSFC/Solar Dynamics Observatory
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA22242

Rhea and Titan

2018-02-08T18:25:00.001+00:00

In this view, Saturn's icy moon Rhea passes in front of Titan as seen by NASA's Cassini spacecraft. Some of the differences between the two large moons are readily apparent. While Rhea is a heavily-cratered, airless world, Titan's nitrogen-rich atmosphere is even thicker than Earth's.

This natural color image was taken in visible light with the Cassini narrow-angle camera on November 19, 2009, at a distance of approximately 713,300 miles (1,148,000 kilometers) from Rhea.

The Cassini spacecraft ended its mission on September 15, 2017.

Image Credit: NASA/JPL-Caltech/Space Science Institute
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21904

TRAPPIST-1 Planets Probably Rich in Water

2018-02-07T18:11:00.006+00:00

A new study has found that the seven planets orbiting the nearby ultra-cool dwarf star TRAPPIST-1 are all made mostly of rock, and some could potentially hold more water than Earth. The planets' densities, now known much more precisely than before, suggest that some of them could have up to 5 percent of their mass in the form of water — about 250 times more than Earth's oceans. The hotter planets closest to their parent star are likely to have dense steamy atmospheres and the more distant ones probably have icy surfaces. In terms of size, density and the amount of radiation it receives from its star, the fourth planet out is the most similar to Earth. It seems to be the rockiest planet of the seven, and has the potential to host liquid water.

Planets around the faint red star TRAPPIST-1, just 40 light-years from Earth, were first detected by the TRAPPIST-South telescope at ESO’s La Silla Observatory in 2016. In the following year further observations from ground-based telescopes, including ESO’s Very Large Telescope and NASA’s Spitzer Space Telescope, revealed that there were no fewer than seven planets in the system, each roughly the same size as the Earth. They are named TRAPPIST-1b,c,d,e,f,g and h, with increasing distance from the central star.

Further observations have now been made, both from telescopes on the ground, including the nearly-complete SPECULOOS facility at ESO’s Paranal Observatory, and from NASA’s Spitzer Space Telescope and the Kepler Space Telescope. A team of scientists led by Simon Grimm at the University of Bern in Switzerland have now applied very complex computer modelling methods to all the available data and have determined the planets’ densities with much better precision than was possible before.

Simon Grimm explains how the masses are found: "The TRAPPIST-1 planets are so close together that they interfere with each other gravitationally, so the times when they pass in front of the star shift slightly. These shifts depend on the planets' masses, their distances and other orbital parameters. With a computer model, we simulate the planets' orbits until the calculated transits agree with the observed values, and hence derive the planetary masses."

Team member Eric Agol comments on the significance: "A goal of exoplanet studies for some time has been to probe the composition of planets that are Earth-like in size and temperature. The discovery of TRAPPIST-1 and the capabilities of ESO’s facilities in Chile and the NASA Spitzer Space Telescope in orbit have made this possible — giving us our first glimpse of what Earth-sized exoplanets are made of!"

The measurements of the densities, when combined with models of the planets’ compositions, strongly suggest that the seven TRAPPIST-1 planets are not barren rocky worlds. They seem to contain significant amounts of volatile material, probably water, amounting to up to 5% the planet's mass in some cases — a huge amount; by comparison the Earth has only about 0.02% water by mass!

"Densities, while important clues to the planets' compositions, do not say anything about habitability. However, our study is an important step forward as we continue to explore whether these planets could support life," said Brice-Olivier Demory, co-author at the University of Bern.

TRAPPIST-1b and c, the innermost planets, are likely to have rocky cores and be surrounded by atmospheres much thicker than Earth's. TRAPPIST-1d, meanwhile, is the lightest of the planets at about 30 percent the mass of Earth. Scientists are uncertain whether it has a large atmosphere, an ocean or an ice layer.

Scientists were surprised that TRAPPIST-1e is the only planet in the system slightly denser than Earth, suggesting that it may have a denser iron core and that it does not necessarily have a thick atmosphere, ocean or ice layer. It is mysterious that TRAPPIST-1e appears to be so much rockier in its composition than the rest of the planets. In terms of size, density and the amount of radiation it receives from its star, this is the planet that is most similar to Earth.

TRAPPIST-1f, g and h are far enough from the host star that water could be frozen into ice across their surfaces. If they have thin atmospheres, they would be unlikely to contain the heavy molecules that we find on Earth, such as carbon dioxide.

"It is interesting that the densest planets are not the ones that are the closest to the star, and that the colder planets cannot harbour thick atmospheres," notes Caroline Dorn, study co-author based at the University of Zurich, Switzerland.

The TRAPPIST-1 system will continue to be a focus for intense scrutiny in the future with many facilities on the ground and in space, including ESO’s Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope.

Astronomers are also working hard to search for further planets around faint red stars like TRAPPIST-1. As team member Michaël Gillon explains: "This result highlights the huge interest of exploring nearby ultracool dwarf stars — like TRAPPIST-1 — for transiting terrestrial planets. This is exactly the goal of SPECULOOS, our new exoplanet search that is about to start operations at ESO’s Paranal Observatory in Chile.”

Image Credit: ESO/M. Kornmesser
Explanation from: https://www.eso.org/public/news/eso1805/

Spiral Galaxy NGC 7331

2018-02-01T19:57:00.002+00:00

This NASA/ESA Hubble Space Telescope image shows a spiral galaxy known as NGC 7331. First spotted by the prolific galaxy hunter William Herschel in 1784, NGC 7331 is located about 45 million light-years away in the constellation of Pegasus (The Winged Horse). Facing us partially edge-on, the galaxy showcases it’s beautiful arms which swirl like a whirlpool around its bright central region.

Astronomers took this image using Hubble’s Wide Field Camera 3 (WFC3), as they were observing an extraordinary exploding star — a supernova — which can still be faintly seen as a tiny red dot near the galaxy’s central yellow core. Named SN2014C, it rapidly evolved from a supernova containing very little Hydrogen to one that is Hydrogen-rich — in just one year. This rarely observed metamorphosis was luminous at high energies and provides unique insight into the poorly understood final phases of massive stars.

NGC 7331 is similar in size, shape, and mass to the Milky Way. It also has a comparable star formation rate, hosts a similar number of stars, has a central supermassive black hole and comparable spiral arms. The primary difference between our galaxies is that NGC 7331 is an unbarred spiral galaxy — it lacks a “bar” of stars, gas and dust cutting through its nucleus, as we see in the Milky Way. Its central bulge also displays a quirky and unusual rotation pattern, spinning in the opposite direction to the galactic disc itself.

By studying similar galaxies we hold a scientific mirror up to our own, allowing us to build a better understanding of our galactic environment which we cannot always observe, and of galactic behaviour and evolution as a whole.

Image Credit: ESA/Hubble & NASA/D. Milisavljevic (Purdue University)
Explanation from: https://www.spacetelescope.org/images/potw1805a/

Star-Forming Region Lupus 3

2018-01-31T19:25:00.002+00:00

A dark cloud of cosmic dust snakes across this spectacular wide field image, illuminated by the brilliant light of new stars. This dense cloud is a star-forming region called Lupus 3, where dazzlingly hot stars are born from collapsing masses of gas and dust. This image was created from images taken using the VLT Survey Telescope and the MPG/ESO 2.2-metre telescope and is the most detailed image taken so far of this region.

The Lupus 3 star forming region lies within the constellation of Scorpius (The Scorpion), only 600 light-years away from Earth. It is part of a larger complex called the Lupus Clouds, which takes its name from the adjacent constellation of Lupus (The Wolf). The clouds resemble smoke billowing across a background of millions of stars, but in fact these clouds are a dark nebula.

Nebulae are great swathes of gas and dust strung out between the stars, sometimes stretching out over hundreds of light-years. While many nebulae are spectacularly illuminated by the intense radiation of hot stars, dark nebulae shroud the light of the celestial objects within them. They are also known as absorption nebulae, because they are made up of cold, dense particles of dust that absorb and scatter light as it passes through the cloud.

Famous dark nebulae include the Coalsack Nebula and the Great Rift, which are large enough to be seen with the naked eye, starkly black against the brilliance of the Milky Way.

Lupus 3 has an irregular form, appearing like a misshapen snake across the sky. In this image it is a region of contrasts, with thick dark trails set against the glare of bright blue stars at the centre. Like most dark nebulae, Lupus 3 is an active star formation region, primarily composed of protostars and very young stars. Nearby disturbances can cause denser clumps of the nebula to contract under gravity, becoming hot and pressurised in the process. Eventually, a protostar is born out of the extreme conditions in the core of this collapsing cloud.

The two brilliant stars in the centre of this image underwent this very process. Early in their lives, the radiation they emitted was largely blocked by the thick veil of their host nebula, visible only to telescopes at infrared and radio wavelengths. But as they grew hotter and brighter, their intense radiation and strong stellar winds swept the surrounding areas clear of gas and dust, allowing them to emerge gloriously from their gloomy nursery to shine brightly.

Understanding nebulae is critical for understanding the processes of star formation — indeed, it is thought that the Sun formed in a star formation region very similar to Lupus 3 over four billion years ago. As one of the closest stellar nurseries, Lupus 3 has been the subject of many studies; in 2013, the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatoryin Chile captured a smaller picture of its dark smoke-like columns and brilliant stars.

Image Credit: ESO/R. Colombari
Explanation from: https://www.eso.org/public/news/eso1804/

Havasu Falls

2018-01-29T10:45:00.001+00:00

Havasu Falls is a waterfall of Havasu Creek, located in the Grand Canyon, Arizona, United States. It is within Havasupai tribal lands.

Havasu Falls is located 1 1⁄2 miles (2.4 km) from Supai. It is the more famous and most visited of the various falls along Havasu Creek. It consists of one main chute that drops over a 90-to-100-foot (27 to 30 m) vertical cliff into a series of plunge pools. High calcium carbonate concentration in the water creates the vivid blue-green color and forms the natural travertine dams that occur in various places near the falls.

Due to the effects of flash floods, the appearance of Havasu Falls and its plunge pools has changed many times. Prior to the flood of 1910, water flowed in a near continuous sheet, and was known as Bridal Veil Falls. The notch through which water flows first appeared in 1910, and has changed several times since. Water currently flows as one stream. In the past, there were sometimes multiple streams, or a continuous flow over the edge.

Explanation from: https://en.wikipedia.org/wiki/Havasu_Falls

Globular Cluster NGC 3201

2018-01-28T08:53:00.001+00:00

This image from the NASA/ESA Hubble Space Telescope reveals a glistening and ancient globular cluster named NGC 3201 — a gathering of hundreds of thousands of stars bound together by gravity. NGC 3201 was discovered in 1826 by the Scottish astronomer James Dunlop, who described it as a “pretty large, pretty bright” object that becomes “rather irregular” towards its centre.

Globular clusters are found around all large galaxies, but their origin and role in galaxy formation remain tantalisingly unclear. Astronomers recently discovered a black hole lurking at the heart of NGC 3201 — its position was revealed by the strange movements of a star being quickly flung around a massive, invisible counterpart. This sparkling group of stars also has some strange properties which make it unique amongst the over 150 globular clusters belonging to the Milky Way. NGC 3201 has an extremely fast velocity with respect to the Sun and its orbit is retrograde, meaning that it moves speedily in the opposite direction to the galactic centre, which it orbits.

The unusual behaviour of this cluster suggests that it may have extragalactic origins, but at some point was captured by the Milky Way’s gravity. However, the chemical makeup of this intriguing cluster tells a different story — the stars within NGC 3201 are chemically very similar to those of other galactic globular clusters, implying that they formed at a similar location and time to their neighbours.

Whether this mysterious cluster was adopted by our galaxy or has for some reason evolved very differently to the family of clusters it grew up with, it is certainly an unusual astronomical beauty.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1804a/

Great Dust Storms on Mars

2018-01-27T17:00:00.001+00:00

Two 2001 images from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter show a dramatic change in the planet's appearance when haze raised by dust-storm activity in the south became globally distributed.

At left, an image from late June 2001 shows clear conditions over much of the planet, with regional dust-storm activity occurring in the Hellas basin (bright oval feature) near the edge of the south polar cap. At right, a July 2001 image from the same perspective shows the planet almost completely enveloped. Dust extends to altitudes of more than 60 kilometers (37 miles) during global-scale storms.

Although dust storms occur year-round on Mars, they often occur in greater numbers during certain seasons. In particular, it has long been known from Earth-based telescopic observations that the largest, global dust events(those that enshroud the entire planet) occur during the southern spring and summer. As the Mars Global Surveyor (MGS) mission began to monitor this period for the second time, particular attention was paid to local and regional dust storms in anticipation of capturing--for the first time--high spatial-and time-resolution observations of the start of a "global" storm.

Throughout the month of June 2001, the MGS Mars Orbiter Camera (MOC)routinely accumulated low resolution (7.5 km/pixel) global maps of Marson an orbit-by-orbit basis. A moderately large number of local dust storms were noted, especially along the retreating margin of the seasonal south polar CO2 frost cap and around the large and deep Hellas impact basin that dominates the southern, eastern highlands. On June 21, an otherwise undistinguished small dust storm surged into the basin from the southwest. When viewed 24 hours later, the storm had circulated clockwise about 1/3of the circumference of Hellas, indicating relatively high winds. For the next three days, this storm brewed north of Hellas and east towards Hesperia, but didn't cross the equator. Then, sometime between 2 PM local Mars time on June 25 and 2 PM local Mars time on June 26, the storm exploded north across the equator, and in less than 24 hours thereafter, dust was being raised from separate locations in Arabia, Nilosyrtis, and Hesperia, thousands of kilometers away from Hellas. This was the start of the long-anticipated global dust event.

Over the following week, dust injected high into the stratosphere during the initial Hellas and Hesperia storms drifted eastward, carried by the prevailing south circumpolar jet stream. Beneath this "veil" of dust, an intense wind front moved across Mars, setting up conditions for many other local and regional dust storms. By July 4, a large regional storm was raging between Daedalia Planitia south of the Tharsis volcanoes and Syria Planum (just south of Labyrinthus Noctis). Another storm was raising plumes of dust in north central Noachis/southwestern Meridiani. Plumes were rising in Hesperia but not Hellas.

Throughout July and August, MOC observations revealed a general pattern of regional storm centers beneath an ever-spreading veil of stratospheric dust. The Daedalia/Claritas/Syria storm created dust plumes on over 90 consecutive days.

Previous views and perceptions of global dust events had noted regional brightenings within the overall pall of what was called a "global duststorm." From our new observations, we know that at least this global dust "storm" was really a set of storms, somehow triggered to occur at the same time. We also know that dust was not raised from everywhere on the surface during this global event, but rather from discrete, long-lived centers of activity. We saw, for the first time, rapid, cross-equatorial flow of dust-raising winds.

Image Credit: NASA/JPL/MSSS
Explanation from: https://photojournal.jpl.nasa.gov/catalog/pia03170

Planetary System Kepler K2-138

2018-01-23T18:22:00.002+00:00

This artist concept shows K2-138, the first multi-planet system discovered by citizen scientists. The central star is slightly smaller and cooler than our Sun. The five known planets are all between the size of Earth and Neptune. Planet b may potentially be rocky, but planets c, d, e, and f likely contain large amounts of ice and gas. All five planets have orbital periods shorter than 13 days and are all incredibly hot, ranging from 800 to 1,800 degrees Fahrenheit.

Image Credit: NASA/JPL-Caltech
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA22088

Star-Forming Region LH 72

2018-01-22T17:08:00.001+00:00

In one of the largest known star formation regions in the Large Magellanic Cloud (LMC), a small satellite galaxy of the Milky Way, lie young and bright stellar groupings known as OB associations. One of these associations, called LH 72, was captured in this dramatic NASA/ESA Hubble Space Telescope image. It consists of a few high-mass, young stars embedded in a beautiful and dense nebula of hydrogen gas.

Much of the star formation in the LMC occurs in super-giant shells. These regions of interstellar gas are thought to have formed due to strong stellar winds and supernova explosions that cleared away much of the material around the stars creating wind-blown shells. The swept-up gas eventually cools down and fragments into smaller clouds that dot the edges of these regions and eventually collapse to form new stars.

The biggest of these shells, home to LH 72, is designated LMC4. With a diameter of about 6000 light-years, it is the largest in the Local Group of galaxies that is home to both the Milky Way and LMC. Studying gas-embedded young associations of stars like LH 72 is a way of probing the super-giant shells to understand how they formed and evolved.

This image was taken with Hubble’s Wide Field Planetary Camera 2 using five different filters in ultraviolet, visible and infrared light. The field of view is approximately 1.8 by 1.8 arcminutes.

Image Credit: ESA/Hubble, NASA and D. A. Gouliermis
Explanation from: https://www.spacetelescope.org/images/potw1147a/

Volcán de Colima Eruption

2018-01-21T14:42:00.000+00:00

Colima, Mexico

January 26, 2017

Image Credit & Copyright: Sergio Tapiro

Globular Cluster Messier 79

2018-01-19T16:10:00.001+00:00

It’s beginning to look a lot like Christmas in this NASA/ESA Hubble Space Telescope image of a blizzard of stars, which resembles a swirling storm in a snow globe.

These stars make up the globular cluster Messier 79, located about 40 000 light-years from Earth in the constellation of Lepus (The Hare). Globular clusters are gravitationally bound groupings of up to one million stars. These giant “star globes” contain some of the oldest stars in our galaxy. Messier 79 is no exception; it contains about 150 000 stars, packed into an area measuring just roughly 120 light-years across.

This 11.7-billion-year-old star cluster was first discovered by French astronomer Pierre Méchain in 1780. Méchain reported the finding to his colleague Charles Messier, who included it in his catalogue of non-cometary objects: The Messier catalogue. About four years later, using a larger telescope than Messier’s, William Herschel was able to resolve the stars in Messier 79 and described it as a “globular star cluster.”

In this sparkling Hubble image, Sun-like stars appear yellow-white and the reddish stars are bright giants that are in the final stages of their lives. Most of the blue stars sprinkled throughout the cluster are aging “helium-burning” stars, which have exhausted their hydrogen fuel and are now fusing helium in their cores.

Image Credit: NASA and ESA, S. Djorgovski (Caltech) and F. Ferraro (University of Bologna)
Explanation from: https://www.spacetelescope.org/images/potw1751a/

Spiral Galaxy NGC 1398

2018-01-18T15:57:00.003+00:00

This picture shows spectacular ribbons of gas and dust wrapping around the pearly centre of the barred spiral galaxy NGC 1398. This galaxy is located in the constellation of Fornax (The Furnace), approximately 65 million light-years away.

Rather than beginning at the very middle of the galaxy and swirling outwards, NGC 1398’s graceful spiral arms stem from a straight bar, formed of stars, that cuts through the galaxy’s central region. Most spiral galaxies — around two thirds — are observed to have this feature, but it’s not yet clear whether or how these bars affect a galaxy’s behaviour and development.

This image comprises data gathered by the FOcal Reducer/low dispersion Spectrograph 2 (FORS2) instrument, mounted on ESO’s Very Large Telescope (VLT) at Paranal Observatory, Chile. It shows NGC 1398 in striking detail, from the dark lanes of dust mottling its spiral arms, through to the pink-hued star-forming regions sprinkled throughout its outer regions.

This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/potw1801a/