• When: Wednesday, September 22, 2010 at 7:07pm (so come at 6:30pm)
• Where: Solstice Park (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
• Who: Everyone welcome, as usual.

Sunset on June 11, 2009 Credit: Jason Gift Enevoldsen

Come watch the autumn equinox sunset at Solstice Park in West Seattle on Monday. We’ll see if the sunset lines up with the placed marker. I’ll be there even if it is cloudy, but not if the weather is miserable.

If it is clear we’ll bring a telescope or two to take a look at the Moon after the Sun goes down – and maybe Jupiter if we stay until it is dark enough.

If you’re interested – here’s the timing of various celestial events on Saturday from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:

Sun and Moon Data for One Day

The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):

Wednesday 22 September 2010 Pacific Daylight Time

SUN
Begin civil twilight 6:25 a.m.
Sunrise 6:56 a.m.
Sun transit 1:02 p.m.
Sunset 7:07 p.m.
End civil twilight 7:38 p.m.

MOON
Moonrise 6:10 p.m. on preceding day
Moon transit 12:11 a.m.
Moonset 6:23 a.m.
Moonrise 6:28 p.m.
Moonset 7:27 a.m. on following day

This event is my part of the NASA’s Solar System Ambassadors program, and thanks to West Seattle Blog for publicizing the last few!

Everyone is welcome, see you there!

~ A l i c e !

It is commonly accepted as a fact that red light doesn’t damage your night vision as much as white light. In practical application this may be a little less straightforward than once thought.

Here’s a short summary to the best of my knowledge about which lights you should use while trying to preserve your night vision:

• When looking at dim pinpoints of light use a fully-dimmable red light – or white if you prefer.
• When spotting silhouettes in the dark use a fully-dimmable white light
• When reading use a fully-dimmable white light, though red will do
• When reading color charts use a fully-dimmable white light

Why Do You Care?

The real question is, what are you planning to do (both with the light and in the dark)? If you’re developing photos you’ll need different conditions than if you plan to go stargazing. The Navy did quite a number of studies on dark adaptation in the mid-eighties. It is my impression they were trying to find a solution that suited the officer of the deck – the guy on the periscope – as well as the other staff in the compartment who have varied duties which don’t require dark adaptation.

A quote from the Naval study on lighting choices in submarines at night:

Red light has been used because it is well established that subsequent dark adaptation is faster than with any other color. However, the magnitude of this advantage depends on the intensity of the adapting light. … The measure that has typically been used to show this phenomenon is the time required to detect pinpoints of light at absolute scotopic threshold–that is, the individual’s maximum sensitivity. Although this is undoubtedly of great importance at times, it is probably true that in most practical situations the observer is required to operate at something less than maximum sensitivity and to detect targets quite different from spots of light.

The Navy also considered the additional eye-fatigue caused by red lighting and low-level lighting, as well limitations such as the inability to distinguish color under red lighting.

The Results

Dark adaptation is faster after exposure to red light, but not by much. Is it enough to be worthwhile? Probably not, but maybe, depending.

The Naval studies found that the benefit gained by using red lights is entirely lost when people were asked to detect silhouettes of ships against a simulated sky. This is at least partially because you don’t need to be fully dark-adapted to see a silhouette. They found that using a very dim white light was just as good.

In order to detect the dimmest possible point of light though, you do need to be fully dark-adapted. You must admit, stargazing is exactly that: trying to see pinpoints of light. So there is a benefit to using a red – but only if you’re going stargazing in an extremely dark place. If you’re stargazing from within a city, you will likely never be somewhere that dark.

Benefits and Caveats

The other major benefit to using a red light is that usually you (or someone else) has put a red filter on that light. This in an of itself dims the light down. You always need to be using the dimmest possible light to keep your night vision – and this applies to red as well as white (or blue or green or purple). If you’re using a superbright red LED flashlight, unless you need that much light, you’re probably losing more night vision than necessary.

Also – that red color that is beneficial to perfect night vision is that rich ruby-red, not so much an orangey-red or pinky-red (those are highly technical terms).

My Recommendation

Keeping whatever light you have as dim as possible is the most important.

Until you can find me a fully-dimmable white flashlight (one that dims smoothly all the way from full-bright to off), I’ll keep using my dying-battery red keychain LED, and single-AA tiny filtered incandescent flashlight. I’ll also probably only use them when I’m digging in my telescope bag or checking the site of my telescope set up to make sure I haven’t left anything behind. Don’t forget – humans have pretty good night vision – use it.

Lastly, assist your fellow stargazers, change any outdoor fixture you can to one that is approved for reducing glare and light pollution by the International Dark-Sky Association.

Where’d I Get My Info?

St. Louis Places – Night Vision is a website that has a thorough and interesting discussion of red light and night vision. He cites good sources, but it is not itself a primary source.

Lurta, S.M. , S. M., and D. A. Kobus. Immediate Visibility after Red and White Adaptation. Submarine Base, Groton, Conn.: Naval Submarine Medical Research Laboratory, 1985. (A Naval study of light adaptation for use in submarines – primary source)

The International Dark-Sky Association

Thanks to Steph Zimmerman for the help in searching out real sources of information on this.

365 Days of Astronomy is awesome – and they’re hosting this as a podcast. Check it out!

~ A l i c e !

Hey, I considered making it the desktop of my computer, but the hilarious, cringe-worthy, winsome, and geektaastic Wil+Felicia won out this week. Maybe next week Rob?

My old posts (please note the dates for observing in these ARE NOT updated to 2010) -

2009 #1 – http://www.alicesastroinfo.com/2009/06/mars-moon-2009-edition-still-not-true/

2009 #2 (just for fun) – http://www.alicesastroinfo.com/2009/06/mars-as-big-as-the-moon-09-2/

2008 (my best) – http://www.alicesastroinfo.com/2008/08/mars-hoax-again-again-and-again/

2007 – http://www.alicesastroinfo.com/2007/08/moon-hoax-again/

2006 – was printed on paper only

2003-2005 – were verbal

::sigh:: I’m sorry to flake out on you this year, but Rob is awesome, and a great substitute. You should follow him anyway. :)

~ A l i c e !

Notable Sky Objects

Here’s a good link for getting rise/set data, and figuring out where to look for planets, comets, and the like: http://www.heavens-above.com/ (don’t forget to put in your location, the link I’ve given you assumes Seattle!).

JUPITER

Although it is not marked on the map, Jupiter rises just after midnight and will be visible in the early morning in the constellation Pisces (beside Pegasus).

VENUS and MARS and SATURN

After sunset watch above the Western horizon as it begins to get dark. You’ll see Venus, Regulus (bright star in Leo) Mars, and Saturn in that order, reading from right to left, making a nice long line across the sky. Venus has been beautiful the times I’ve seen it this month … that is, when the clouds cooperate and part for decent sky viewing. These planets will be visible until just about midnight, setting one by one until then.

COMET MCNAUGHT

As I’ve mentioned before this summer’s Comet McNaught is not the same as the Comet McNaught from a few years ago. Mr. McNaught is prolific in his comet discoveries.  To make sure you’re finding the right information, search for C/2009 R1 McNaught.

McNaught is currently in Gemini, passing close to the Sun which means we can’t see it. In a few weeks it will have passed its closest point to the Sun and will begin to move farther away, passing into our evening sky. Follow the progress at either of these links:

Sky and Telescope

Comet McNaught

EVENTS

July 23- August 22 (peak August 12) – Perseid Meteor Shower, best viewed after midnight, looking towards the constellation Perseus.

New Constellations

Quick note to long-time followers of AstroInfo. The section below is a straight copy-and-paste job from last July-August. The constellations don’t change from year to year, and we’ve got some new people this year who haven’t gotten the information below. Hey, perhaps you need a quick refresher too, after all, it has been a whole year. In any case, if you prefer to stop reading here I will not be offended.

AQUILA – The Eagle

SCIENCE: Altair is the BEST star in the whole sky (because I’m named after it).
MYTH: Tanabata: there are versions of this myth all over Asia, all slightly different, but all telling the same basic story. This is one of the Japanese versions. Kengyuu (Altair) is a cowherder boy and he is in love with Orihime (Vega) the weaver princess. They are so in love that they forget to do their chores, and the Emperor decides to punish them. He places them in the sky on opposite sides of Amanogawa, the River of Heaven (the Milky Way) so they cannot meet. The magpies take pity on them, and one day out of the year, on the seventh day of the seventh lunar month (August 26th, 2009), they build a bridge over the Milky Way so the lovers can be together. Unfortunately, if it is raining or cloudy, the magpies are not able to build the bridge.

ANDROMEDA – The Princess

SCIENCE: M31- The Andromeda Galaxy is visible to the naked eye, and better through a telescope.
MYTH: Saudi Arabians called Andromeda “the sea lion”. To the Phoenicians, the whole part of the sky where Andromeda is seen as a threshing floor, and the constellation is a grain thresher working

PERSEUS – Perseus

SCIENCE: The Perseid Meteor shower appears to radiate out of the constellation Perseus. The point meteors all appear to originate is called the “radiant.”
MYTH: For the ancient Chinese, the right side of the constellation Perseus is the Mausoleum. The star just inside the right-hand curl is Jishi – the Heap of Corpses.

PEGASUS – The Flying Horse

SCIENCE: The star at the tip of the horse’s head is called Enif, which means “nose.”
MYTH: The two northernmost stars in the Great Square of Pegasus (α And, and γ Peg: the star attached to Andromeda, and the star next to it that is part of the horse’s back) are the “Encampment” in Chinese mythology. There are three pairs of stars scattered near this asterism which are Ligong or “Resting Places” for the Emperor.

CAPRICORNUS – The Sea Goat

SCIENCE: Jupiter is right beside Capricornus this month.
MYTH: Part of Capricornus along with parts of Pisces and Aquarius make the “Line of Ramparts” in ancient Chinese mythology – a line of fortresses built by the celestial army. Since I can’t read Chinese, I can’t tell you exactly which stars these are, but check the Chinese Starmap.

“Tiny” Guys

Going for the Gold? Here’re this month’s itty-bittys.
CANES VENATICI – The Hunting Dogs
COMA BERENICES – Berenice’s Hair
SERPENS – The Serpent
LIBRA – The Scales
SCUTUM – The Shield
VULPECULA – The Fox
SAGGITA – The Arrow
EQUULEUS – The Horse
LACERTA – The Lizard
TRIANGULUM – The Triangle
LEO MINOR – The Small Lion (Between the Big Dipper and Leo)
CAMELOPARDALIS– The Giraffe
LYNX – The Lynx

Returning Constellations

DELPHINUS – The Dolphin
LYRA – The Lyre
CYGNUS – The Swan
SCORPIUS – The Scorpion
BOÖTES – The Herdsman
HERCULES – Hercules
CORONA BOREALIS – The Northern Crown
CEPHEUS – King Cepheus
DRACO – The Dragon
URSA MAJOR – The Great Bear
URSA MINOR – The Little Bear
CASSIOPEIA – The Queen

Where’d I Get My Info?

My memory, and Zeta Strickland
CHAN Ki-hung, Chinese Ancient Starmap, 2007

~ A l i c e !

Wait, what’s Ocean Watch?

Pacific Science Center and Sailors for the Sea have just completed Around the Americas: a science outreach project to sail all the way around both North and South America (including through the Nortwest Passage). The boat they sailed was called Ocean Watch, and they did all kinds of fun science and activities with people at every port of call.

Mission:

Around the Americas is a 25,000 mile sailing circumnavigation of the American continents with the mission of inspiring, educating, and engaging citizens of the Americas to protect our fragile oceans.

Back when I was a kid the Northwest Passage didn’t exist, so this would have been impossible, and now not only is it possible, but my friend Zeta sailed through it. This wasn’t that long ago either … the ice really is melting.

Ocean Watch arrived back in Seattle today (June 17, 2010).

What does that have to do with Mars?

Nothing. But Dr. Amy Knudson from the Planetary Science Institute was volunteering with Pacific Science Center during the exhibit Facing Mars, and she works with the Mars Exploration Rovers doing soil analysis among other things. She was asking if we had recommendations for naming little things on Mars. The names had to be nautical, so I told her about Around the Americas and Ocean Watch. A few weeks later she returned, telling us that she’d proposed the name for one of the patches of soil she was analyzing and it had been accepted!

She’s just sent me some photos of Ocean Watch on Mars as taken by Opportunity (also known as Mars Exploration Rover B). She is continuing to name other soils and rocks after Around the Americas’ ports of call.

Show Me the Dirt*!

Ocean Watch (a soil on Mars) - field of view approximately 1/2 meter by 1/2 meter.
Photo credit: D. Savransky and J. Bell (Cornell) / JPL / NASA

Opportunity took this picture on Sol 2225 (martian day 2225) with its panoramic camera. This image is approximately true color, and shows a small impression where Opportunity’s instrument rested during the soil analysis.

Nothing has been released about the analysis of this soil yet – so your best guess about that texture is just great. Be the scientist – what do you think those “bubbles” are? Are they depressions or spheres? Are they hard? Soft? Are they just shapes in the sand that are easily disrupted or are they harder? Look at how they are different when they’ve been pressed by the instrument. Does that help you determine what they’re like? What might have caused them?

Ocean Watch soil through Microscopic Imager (3cm by 3cm)

Using the microscopic imager Opportunity took a close up picture of the soil before deploying the “IDD” – the “Instrument Deployment Device” – also known as the arm.

Ocean Watch with impression (3cm by 3cm)

Using the microscopic imager Opportunity took another close up picture of the soil AFTER deploying the arm. You can see where the instrument rested in the upper right of the picture. Some of the little bubbles or depressions are flattened, and others have been entirely squished.

Naming on Mars

If you follow the rover missions you’ll have heard of rocks and landforms on Mars named things like “Chocolate Hills,” “Concepcíon,” “Columbia Hills,” “Endurance,” or “Jenny.” Naming of objects in the solar system has to go through the International Astronomical Union (IAU), which can take years. In order to stay sane and not constantly have to say to each other “let’s take a look at that rock” or “shall we drive to crater 001-5BX?” the technicians and scientists working with the Mars rovers assign their own names to these items. Ocean Watch is such a name. I find it likely that many of these names will stick – having been used for years by the time the IAU has time to choose official names – but some will be changed, and some are of locations too small for anyone to care about once the rover has driven on. Ocean Watch is a very small patch of soil (about 1/4 of a square meter), so who knows what will happen.

For now though, a little patch of a distant planet holds a name that reminds us of the fragility of our own planet, and honors the excitement of doing science and science outreach.

Want More?

More information about this soil will eventually be posted in the MER Analyst’s Notebook.

*Technically I wouldn’t use the word “dirt” because that tends to imply organic content … but, forgive me this time.

Thank you, Amy.

~ A l i c e !

Sunset on June 11, 2009 Credit: Jason Gift Enevoldsen

Come watch the summer solstice sunset at Solstice Park in West Seattle on Monday. We’ll see if the sunset lines up with the placed marker. I’ll be there even if it is cloudy because sometimes the Sun peeks through just as it begins to set, but if it is driving rain I’m staying home with a cup of tea.

If it is clear we’ll bring a telescope or two to take a look at the Moon after the Sun goes down – and Mars and Saturn if we stay until it is dark enough. We will not be able to see the comet – that rises a little before 3am, and I plan to get some sleep before Tuesday. You’re welcome to look for the comet on your own though!

If you’re interested – here’s the timing of various celestial events on Saturday from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:

Sun and Moon Data for One Day

The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):

Monday   21 June 2010          Pacific Daylight Time

SUN
Begin civil twilight       4:31 a.m.
Sunrise                    5:11 a.m.
Sun transit                1:11 p.m.
Sunset                     9:11 p.m.
End civil twilight         9:52 p.m.

MOON
Moonrise                   3:29 p.m. on preceding day
Moonset                    1:36 a.m.
Moonrise                   4:45 p.m.
Moon transit               9:29 p.m.
Moonset                    2:05 a.m. on following day

This event is my part of the NASA’s Solar System Ambassadors program, and thanks to West Seattle Blog for publicizing the last few!

Everyone is welcome, see you there!

~ A l i c e !

In short – the Kepler Mission is a telescope in orbit that is pointed at the exact same patch of sky for a period of four years (starting in 2009). It is detecting planets around other stars via the so-called transit method – watching as planets transit in front of their stars. By watching for five years it should be able to detect hundreds (if not thousands) of planets in Earth-like orbits, and therefore plenty of planets in their stars habitable zones.

Where is Kepler Looking?

Kepler is closely watching a little patch of sky by the constellation Cygnus, pointed along our little section of the Milky Way, carefully avoiding all the brightest stars.

From NASA: Kepler's Field of View (Angle 1)

From NASA: Kepler's Field of View (Angle 2)

The Kepler Technology

Advanced gyroscopes onboard Kepler keep it pointed in exactly the same direction so the scientists at JPL can get unwavering readings on each star in Kepler’s field of view. To detect planets and calculate their orbits with certainty Kepler will have to watch each planet transit two or three times at least. For a planet like Earth, in its star’s habitable zone, the orbit takes about a year. Different sizes and temperatures of stars have habitable zones at different distances, but the Kepler mission will be able to do a good job at detecting planets with orbital periods up to about two years.

Look at this beautiful picture of the Kepler CCD array (from NASA). Ooo! Shiny!

New News: Hundreds of Planet Candidates Found

Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority are Found to be Neptune-Size and Smaller

Authors: William J. Borucki, for the Kepler Team

(Submitted on 14 Jun 2010)

Abstract: In the spring of 2009 the Kepler Mission conducted high precision photometry on nearly 156,000 stars to detect the frequency and characteristics of small exoplanets. On 15 June 2010 the Kepler Mission released data on all but 400 of the ~156,000 planetary target stars to the public. At the time of this publication, 706 targets from this first data set have viable exoplanet candidates with sizes as small as that of the Earth to larger than that of Jupiter. Here we give the identity and characteristics of 306 of the 706 targets. The released targets include 5 candidate multi-planet systems. Data for the remaining 400 targets with planetary candidates will be released in February 2011. The Kepler results based on the candidates in the released list imply that most candidate planets have radii less than half that of Jupiter.

Comments:	Paper to accompany Kepler’s June 15, 2010 data release; to be submitted to Astrophysical Journal
Subjects:	Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:	arXiv:1006.2799v1

(added 6/15/2010 3pm)

Want More?

Kepler’s Website (Official Honoree of the Webby Awards!)

The New Worlds Atlas

The Extrasolar Planets Encyclopaedia – a good resource for the latest exoplanet totals and discoveries.

~ A l i c e !

arXiv:1006.2799v1 [astro-ph.EP]

Space Weather News for June 8, 2010
http://spaceweather.com

NEW COMET McNAUGHT: A fresh comet is swinging through the inner solar system, and it is brightening rapidly as it approaches Earth for a 100 million mile close encounter in mid-June. Comet McNaught (C/2009 R1) has a vivid green head and a long wispy tail that look great through small telescopes. By the end of the month it could be visible to the naked eye perhaps as bright as the stars of the Big Dipper. Because this is the comet’s first visit to the inner solar system, predictions of future brightness are necessarily uncertain; amateur astronomers should be alert for the unexpected. Visit http://spaceweather.com for sky maps, photos and more information.

You are subscribed to the Space Weather mailing list, a free service of Spaceweather.com.

New subscribers may sign up for free space weather alerts at http://spaceweather.com/services/ .

~ A l i c e !

Edit 5/17 5pm PST: Launch scrubbed due to weather. The window is open until June 3, other wise Junya Terazono suggests that it may be launched in May 2011. No official word on any of that yet though.

Emily on Twitter
Edit 5/17 11:45pm PST: Launch rescheduled to May 21 6:58 (Japan time).

The JAXA/Akatsuki Twitter account (you might need THIS)

Edit 5/22 IKAROS launched successfully and powered up!

Solar Sails

Sounds like science fiction, but a solar sail is pushed by the photons from the Sun. That’s right, you’re using sunlight to sail, not the solar wind. The Planetary Society has a full explanation, but  when a photon is reflected it exerts a small force on the surface reflecting it. The Sun certainly generates a lot of photons, so if you have a large, lightweight, reflective surface, it will be pushed by the force of many photons being reflected off it. Just like a sailboat, the larger your sail the more wind (or in this case reflected photons) you can catch.

And therein lies the problem. Photons are very small. Very, very small. Imagine an regular ant trying to push a semi-truck. Not gonna work – though in a perfect situation there would be some small effect. How many ants do you think you would need? Would all those ants be able to push on the truck or would there be too many of them? A solar sail needs to be huge, and extremely lightweight.

IKAROS

JAXA and The Planetary Society are both done with solar sails being relegated to science fiction just because of the technical challenges. JAXA’s decided to combine a solar sail with solar in order to demonstrate some of the possibilities awaiting us. Their “sail” is covered in solar panels, so in addition to being pushed by the light from the Sun they’ll be generating power. The main mission objectives: prove that a spacecraft can be propelled by a solar sail, and prove that the thin solar panel membranes they’ve chosen do generate power.

Ikaros will unfurl its sail by spinning. You can see this in their video, the spinning starts around 06:50. The video is in Japanese, but you don’t need to understand what they’re saying to want an umbrella that works this way!

Daedalus and Icarus

Daedalus was imprisoned in a tower with his son Icarus, so he built a pair of wings for each of them. The feathers were fastened to the frame with wax, so Daedalus warned his son not to fly too close to the Sun. Of course, being a young boy Icarus ignored his father. He flew so high the wax melted, the wings broke, and he tumbled to his death in the raging sea below. Daedalus escaped successfully and lived safely for a while after that.

That’s the myth as I’ve heard it – I think I’d prefer to name my test mission after Daedalus.

Questions I had after reading about IKAROS:

• Does IKAROS have an ion engine? No, that’s an application of combining solar sails with other propulsion that JAXA’s website proposes.
• Is IKAROS going to Venus? Well, it’ll be on a trajectory towards Venus, but it won’t be able to do orbit insertion so it will just do a far-away fly-by.

Want More?

IKAROS at JAXA

JAXA (the Japanese Space Agency)

The Planetary Society’s Light Sail

~ A l i c e !

Oh, and don’t forget your blue/red 3-D glasses …

~ A l i c e !