New User

Welcome to AOAS.ORG
Wednesday, April 23 2014 @ 06:52 PM CDT

Email Article To a Friend View Printable Version

Astronomy From Your Backyard - 9/29 to 10/5 2010

By Dave Grosvold

The weather this week will be absolutely perfect for sky-watching, with low humidity providing above-average transparency all week and the temperatures low enough after dark to make it very comfortable.

By Wednesday, the Moon will not rise until 11:03 PM CDT, late enough that the glare will no longer interfere with evening observing. The Moon reaches Last Quarter at 10:53 PM CDT on Thursday evening, though it will not rise until after midnight. Moonrise occurs about an hour later each night.

With the Moon gone from the evening sky, now is the time to start looking for Comet 103P/Hartley (Hartley 2.) Comet Hartley 2 is just now becoming visible, reaching magnitude 5.9 on Wednesday evening. Comet Hartley 2 should brighten to magnitude 5.4 by Tuesday evening. The comet will continue to brighten in magnitude over the next three weeks.

Wednesday evening, 103P/Hartley lies in the north-northeast, in the constellation of Cassiopeia, the Beauty Queen, approximately 0.87 above Zeta Cassiopeiae. Over the course of the week, Comet Hartley 2 will track down to the southwest, as shown in the finder chart. At magnitudes dimmer than 5, you will need binoculars or a small telescope to see Comet Hartley 2 in any but the darkest of skies.

In late evening, as Jupiter rises high in the southeast, look for Fomalhaut, (pronounced FOAM-a-lot, or less commonly, FOAM-al-howt.) Fomalhaut is known as the Autumn Star, sparkling far to Jupiter's lower right in the south-southeast. The name Fomalhaut means "the mouth of the whale" in Arabic, and it is the brightest star in the constellation Piscis Austrinus, the Southern Fish.

Uranus, at magnitude 5.7, is only 1° to 1.5° to the left of Jupiter this week, still close, but you may need to move a few field-of-view widths in a telescope or binoculars to spot it. Neptune is also a relatively easy target early in the evening on the border between Capricornus, the Goat-Horn, and Aquarius, the Water Bearer. Can you see any color in Uranus and/or Neptune? There should be just the tiniest hint of pale green in Uranus and an equally pale blue in Neptune.

Even though Venus is at its brightest now at magnitude –4.8, it is becoming a thin, long crescent. Venus is sinking very low in the southwest during bright twilight, setting well before dark ahead of Mars, 6.5° to Venus's upper right all week. That's about one field-of-view width in a typical pair of 7 x 50 binoculars, which you'll definitely need to spot either of them.

Mercury is still very bright at magnitude -1, and is a fine morning target for planet watchers. Once again this week, look for it low in the east about 45 minutes before sunrise. It sinks lower as the week advances, getting lost in the glare of the sun by mid-next week.

After Venus sets, look to the west-northwest, and notice that five constellations form a line descending from the zenith down to the horizon. Remember from earlier articles that the zenith is the point directly overhead from your observing position. Near the zenith is the bright star Deneb: the head of the Northern Cross asterism, which is actually the tail of Cygnus, the Swan. Next down is Lyra, the Lyre, with the bright star Vega, then comes dim Hercules, the Kneeler, the then little Corona Borealis, the Northern Crown, and finally big Boötes, the Herdsman, with bright reddish Arcturus low in the west-northwest.

Hiding in Hercules is one of the most beautiful jewels of the night sky, the Great Cluster in Hercules (M 13,) the brightest globular cluster in the northern hemisphere. M 13 lies two-thirds of the way along the longest side of the Keystone asterism, a quadrangle in Hercules formed by the stars Pi (π,) Eta(η,) Zeta(ζ,) and Epsilon (ε) Herculis. Look about mid-way up to the zenith in the west-northwest for the Keystone, and then look to the north end of the longest side to find M 13,in a clear dark sky, it should be visible as a fuzzy patch slightly larger than a star. A telescopic view reveals a myriad of stars swarming around in a big ball — about a hundred thousand of them in all. M 13 is a spectacular sight on a crisp clear night like the ones we'll have this week, and should not be missed.
Email Article To a Friend View Printable Version

Preservation of the Horn Antenna

General News

Dear Members of the Arkansas Oklahoma Astronomical Society

      I am writing every Astronomy Club and Astronomical Society that I can, individually, to ask for your assistance in saving the Bell Labs Horn Antenna from ruin. I am not selling anything nor am I asking for money. This is not SPAM nor is it an automated email. If you are like me, you are not an activist at heart but just want to enjoy the science of astronomy with friends and associates.  To do this we are, as Sir Isaac Newton put it so succinctly, “Standing on the shoulders of giants”. Arno Penzias and Robert Wilson were not the tallest of those giants but they did make a revolutionary discovery when they used the Horn Antenna to discover the Cosmic Microwave Background Radiation left from the Big Bang creation of the universe. Penzias and Wilson were awarded Nobel Prizes and went on to have successful careers.  The Horn Antenna underwent a much different fate. It was soon surpassed by newer technology and abandoned. In 1989 it was awarded the status of a National Historic Landmark and you would have thought that having that status would have provided it with the care and maintenance it required and deserved. Unfortunately, that was not the case. The National Park System has no power to force the owners and caretakers of National Historic Landmarks to provide any care at all. Because of this, it was easy for Alcatel-Lucent Technologies, the company that took over Bell Labs in Holmdel, New Jersey, to simply ignore their civic obligation. A personal visit to the site revealed to me that they had done just that. I ask that you look at the web site that I have created, www.hornantennatoday.com and to recommend it to the members of your Astronomical organization.

     Once you have seen what has become of that once great technological marvel I hope that you will feel the sadness and anger that I feel. If you do, I ask that you email Paul Ross, Director of Corporate Communications for Alcatel-Lucent Bell Lab at, Paul.Ross@alcatel-Lucent.com and urge that the Horn Antenna be donated to either the National Radio Astronomy Observatory in Green Bank, West Virginia or The Smithsonian Institute in Washington D.C.

     Please let me know that you have done this so that, once they know that I am not alone in this quest, I can contact them again and try to lead them to the proper decision.

     Any help that you provide will be very helpful and appreciated more than you will ever know. Sometimes I feel like Don Quixote on his lone quest.

     I thank you for your time and cooperation.

Cordially yours,

Allan Cook, Amateur Astronomer


Email Article To a Friend View Printable Version

Astronomy From Your Backyard - 9/22 to 9/28 2010

By Dave Grosvold

Wednesday evening, Jupiter and Uranus were almost directly below the full Harvest Moon, which is officially full at 4:18 AM CDT Thursday morning. Also on Wednesday evening, the Autumn Equinox for the Northern Hemisphere occurred at 10:09 PM CDT. This time of year, the equinox marks the beginning of Autumn at the point when daylight and darkness are the same length. The Full Moon closest to (either preceding or following) the Autumn Equinox is known as the Harvest Moon. In any given year, the Harvest Moon can occur as early as September 8th, or as late as October 7th.

This year, however, the Harvest Moon and the Autumn Equinox occur on the same night. Some astronomers refer to this event as a Super Harvest Moon. The coincidence of these two events happens about once every twenty years, and so the event is relatively rare. The “Super Harvest Moon” nickname seems to be a relatively recent invention, but as young as it is, it has made its way into the media this year.

One unusual aspect of a Super Harvest Moon is that “twilight” is truly what the term implies — two separate light sources, the Sun and the Moon, are directly opposite one another in the sky. Therefore the Earth is bathed completely in light from both sides. As a result, the evening light takes on an unusual appearance, and can be seen for about three days surrounding the Equinox.

Jupiter and Uranus are still very close together this week and can be spotted in a wide-field telescope or binoculars. See if you can pick out the Galilean Moons in a pair of binoculars as well.

This time of year after nightfall, the dim Little Dipper (Ursa Minor) is upside down (you'll need a fairly dark sky,) and looks like it's dumping water into the bowl of the Big Dipper (Ursa Major) far below it. Perhaps this is a harbinger of the coming autumn rains!

Venus, is very low in the southwest during brighter part of twilight. It sets before dark, but is visible as it is at its brightest point of the year at magnitude -4.8. Mars is quite a bit dimmer than Venus at magnitude 1.5, and is 6° or 7° to Venus's upper right all week. A pair of binoculars may mean the difference between spotting Mars or not.

Mercury is brightening from magnitude 0.0 to –0.8. Look for it low in the east about 45 minutes before sunrise. Look for Regulus twinkling above or to the upper right of Mercury, rising higher every morning. Regulus marks the base of the Sickle, an asterism in the constellation Leo.

Neptune and Uranus are both visible in the evening sky this week, but may take some patience to spot. As mentioned earlier, Uranus is very close to Jupiter and can be easily found in binoculars. Neptune, however, will probably require higher magnification. See last week's Backyard Astronomy article for help in finding Neptune.

On Monday and Tuesday evening, the waning gibbous Moon will not rise until after 9:00 PM, giving us a wonderful opportunity to get a good view of NGC 869 and NGC 884, a pair known as the Double Cluster, in the constellation Perseus. The Double Cluster is a beautiful pair of large open clusters that are actually visible to the naked eye when viewed from a dark sky. They can be found in the seemingly empty space between Perseus and Cassiopeia in the northeastern sky. A low-power view through binoculars or a telescope reveals a myriad of tiny points of light sparkling in the darkness. A beautiful sight for anyone!
Email Article To a Friend View Printable Version

The Hunt is On!

NASA Space PlaceBy Carolyn Brinkworth

Artist’s rendering of hot gas planet HD209458b. Both the Hubble and Spitzer Space Telescopes have detected carbon dioxide, methane, and water vapor — in other words, the basic chemistry for life — in the atmosphere of this planet, although since it is a hot ball of gas, it would be unlikely to harbor life.
Click image for larger view
The world of astronomy was given new direction on August 13, 2010, with the publication of the Astro2010 Decadal Survey. Astro2010 is the latest in a series of surveys produced every 10 years by the National Research Council (NRC) of the National Academy of Sciences. This council is a team of senior astronomers who recommend priorities for the most important topics and missions for the next decade.

Up near the top of their list this decade is the search for Earth-like planets around other stars — called “extrasolar planets” or “exoplanets” — which has become one of the hottest topics in astronomy.

The first planet to be found orbiting a star like our Sun was discovered in 1995. The planet, called “51 Peg b,” is a “Hot Jupiter.” It is about 160 times the mass of Earth and orbits so close to its parent star that its gaseous “surface” is seared by its blazing sun. With no solid surface, and temperatures of about 1000 degrees Celsius (1700 Fahrenheit), there was no chance of finding life on this distant world. Since that discovery, astronomers have been on the hunt for smaller and more Earth-like planets, and today we know of around 470 extrasolar planets, ranging from about 4 times to 8000 times the mass of Earth.

This explosion in extrasolar planet discoveries is only set to get bigger, with a NASA mission called Kepler that was launched last year. After staring at a single small patch of sky for 43 days, Kepler has detected the definite signatures of seven new exoplanets, plus 706 “planetary candidates” that are unconfirmed and in need of further investigation. Kepler is likely to revolutionize our understanding of Earth's place in the Universe.

We don't yet have the technology to search for life on exoplanets. However, the infrared Spitzer Space Telescope has detected molecules that are the basic building blocks of life in two exoplanet atmospheres. Most extrasolar planets appear unsuitable for supporting life, but at least two lie within the “habitable zone” of their stars, where conditions are theoretically right for life to gain a foothold.

We are still a long way from detecting life on other worlds, but in the last 20 years, the number of known planets in our Universe has gone from the 8 in our own Solar System to almost 500. It's clear to everyone, including the Astro2010 decadal survey team, that the hunt for exoplanets is only just beginning, and the search for life is finally underway in earnest.

Explore Spitzer’s latest findings at http://www.spitzer.caltech.edu. Kids can dream about finding other Earths as they read “Lucy’s Planet Hunt” at http://spaceplace.nasa.gov/en/kids/storybooks/#lucy.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Email Article To a Friend View Printable Version

Astronomy From Your Back Yard - 9/15 to 9/21 2010

By Dave Grosvold

This week, the Moon is just past First Quarter, and shines to the left of the handle of the Sagittarius Teapot on Friday evening. Watch over the course of the next week, and you can observe the waxing gibbous Moon appear farther eastward in the sky at the same time each night.

This is a good time to view most of the planets in the Solar System. On Friday and Saturday evenings, Uranus will come within 0.8° of Jupiter. Uranus is easily visible in binoculars at magnitude 5.7, just to the north of mighty Jupiter, who is nearly 3,000 times brighter at magnitude –2.9. In binoculars or a small telescope with a low-power eyepiece, Pale-green Uranus appears about as bright as one of Jupiter's four Galilean Moons. Mercury is should be clearly visible low in the east about 45 to 30 minutes before sunrise all this week. It's easy to confuse Mercury with Regulus in the dim light of dawn. Regulus lies almost directly above it at the base of the Sickle of Leo.

Venus is now setting in the west before dark, and Mars is about 6° to the right, just above her. Mars is almost lost in the glow of sunset, so you may need binoculars to get a good view.

Jupiter reaches opposition on the night of Monday, the 20th. Opposition occurs when Jupiter is directly opposite the Sun in the sky as seen from Earth. Rising just after dusk in the east southeast, Jupiter is the brightest object in the sky after Venus sets. This year at opposition, Jupiter will be closer to Earth than at any other time from 1963 to 2022, and even though it's only about 1% to 2% larger than the preceding and following oppositions, Jupiter now appears nearly 49 arc-seconds wide. With the South Equatorial Belt still nearly invisible, the Great Red Spot is easy to identify in a small telescope.

Saturn is now completely lost in the glow of sunset, and won't be visible again until late October, when it appears in the eastern sky at early dawn.

Neptune, at magnitude 7.8, is visible in east-southeast about an hour after dark, and lies between the constellations of Capricornus and Aquarius. You can pick it out from a good dark-sky site, and a telescope will reveal it's pale, blueish-tinged disk.

Did you know about the supposedly “secret” US spaceplane? X-37B, the unmanned successor to the space shuttle, launched from Florida in April 2010 and began its first mission with very little public notice – because no one knew where it was going or what it was doing. The spaceplane was shrouded in operational secrecy. However, civilian specialists reported that it might go on mysterious errands for as long as nine months before touching down again.

Even though the X-37B mission was — and remains — secret, amateur astronomers first identified it after observing the object and determining it was orbiting the Earth once every 90 minutes at an inclination of 39.99 degrees. They then shared their findings with other amateurs, who have confirmed their observations and helped determine that the object was indeed the X-37B.

If the weather allows, you can catch the X-37B as it passes overhead every night this week. The X-37B does not reach anywhere near the brightness of Iridium Flares or even the International Space Station (ISS), but with magnitudes between 5.5 and 2.2, you can spot it if the conditions are right. The brightest passes occur on Saturday and Sunday evenings at magnitude 2.2 and 2.3 respectively. Look for it to pass high at altitude 85° in the south-southwest on Saturday evening at 8:35 PM CDT. Look again on Sunday evening at 7:51 PM CDT, only this time it will be at altitude 78° in the north-northeast.

For comparison, the following stars are very close to magnitude 2.2 in brightness: Denebola in Leo (Beta Leonis,) Almach in Andromeda (Gamma Andromedae,) and Mizar A in Ursa Major (Zeta Ursa Majoris.)

The ISS makes one pass overhead this week, at magnitude -0.8. Look for it to pass low in the southwest at 7:50 PM CDT on Friday, the 17th. There will also be several very bright (magnitude -8.0) Iridium Flares visible right at dusk this Thursday, Friday and Saturday. Check out the specific times and celestial coordinates for the X-37B, ISS, and Iridium Flares at the Heavens-Above web site.
Email Article To a Friend View Printable Version

Astronomy From Your Back Yard - 9/1 to 9/7 2010

By Dave Grosvold

The Last-Quarter Moon occurs at 12:22 PM CDT on Wednesday afternoon. Fortunately, moonset occurs before dusk until early next week so we are lucky to have dark skies in the evening for observations.

On Wednesday and Thursday evenings, Venus, Spica, and Mars form a fairly straight line about 5° long, low in the west-southwest about a half hour after sunset as shown in the illustration. Despite how it appears in the image, Venus is over 175 times brighter than Spica, even though Spica is the brightest star in the constellation Virgo!

Beginning in September, the Great Square, an asterism in the constellation Pegasus has risen well up in the eastern sky after dark. The Great Square appears to be balanced on one corner, the sign of autumn to come. This year, bright Jupiter becomes a helpful landmark, shining to the lower right of the Great Square. The lower left corner star in the Great Square is Alpheratz, which is actually in the constellation Andromeda, rather than Pegasus.

From Alpheratz, follow the stars of Andromeda in a diagonal line down to the left of the Great Square, to Mirach, the second star from Alpheratz in the line. Then follow a line straight up from Mirach to the next brightest star, Mu Andromedae (μ And), and then beyond that to an even dimmer star, known as Nu Andromedae (ν And). Directly above and to the right of ν And, you will find the Great Galaxy in Andromeda, or M31. Also known as the Andromeda Galaxy, at a distance of 2,500,000 light years from Earth, M31 is one of the most distant galaxies in the night sky that can be seen from Earth with the naked eye.

If you find the right combination of a dark night, good transparency, and you've taken the time to get your eyes dark-adapted (1.5 hours or more,) you should be able to see this wonder of the heavens as a dim smudge just above ν And. A good pair of binoculars will bring the smudge out to a very prominent hazy streak across the field of view.

M31 is actually 6 times larger than the Full Moon when viewed through a large telescope, but the surface brightness is so low that you only see the center of the galaxy with the naked eye or binoculars. With a small telescope, see if you can pick out the two companion galaxies, M32 and M110. In a medium-sized telescope (8" - 12",) you should be able to see a wonderful image of the galaxy, including M32 and M110. It's almost as good as a photograph!

Like M31, M33, the Triangulum Galaxy, Is another great deep sky target, and it lies just below Mirach in Andromeda, and above and to the right of the constellation Triangulum. M33 is also visible to the naked eye in the right conditions. The Triangulum Galaxy is somewhat more distant from us than M31 at 3 million light years. That's a long way to see without any kind of optical aid!

Although both are spiral galaxies, the Triangulum galaxy presents itself to us face-on, so we can see the spiral structure much more prominently than we can with M31, which is situated at an angle to us. Along with the Milky Way and the Andromeda Galaxy, the Triangulum Galaxy is part of the Local Group of galaxies, being the third largest. The Local Group also includes about 30 smaller galaxies. The galaxies in the Local Group are gravitationally bound together, so as a whole, they move through space as one, even though the individual members are moving around within the group - sort of like a swarm of bees!
Email Article To a Friend View Printable Version

Bogus E-Mails Regarding Mars' Close Approach

Myths & LegendsUpdate: 5 Yep, it's BAAAACK!

Mars Hoax rises Ugly, Gullible Head ONCE AGAIN for 2010! LOL...........It MUST be August!

Update 4: July 10, 2009.....and AGAIN, and AGAIN, AND AGAIN WHEN WILL IT END? Probably won't ever end as long as people don't think before they send misinformation on to others or to other groups. PLEASE READ AND SEND THIS ON TO SOMEONE EACH TIME YOU HEAR THIS HOAX.

UPDATE 3: August 3, 2007 AND.....HERE WE GO AGAIN! Will this crap NEVER END?

For the last FOUR years, this email has surfaced. Its a LIE!

UPDATE 2: August 15, 2006 Every August for the last three years, these crazy emails have started floating around, and people who simply don't know the difference just send them on to their circle of friends without ever trying to learn whether it's the truth they're sending, or whether its just more BOGUS EMAILS

UPDATE 1: AUGUST 10, 2005....The Astronomy Picture of the Day for August 8 echoes my article. They, too, wonder how people can believe these things. Check it out at: http://antwrp.gsfc.nasa.gov/apod/ap050808.html
Or what NASA Science News says at:http://science.nasa.gov/science-news/science-at-nasa/2010/25aug_marshoax/
Have you received any email messages about a close approach of Mars?

(Originally posted Aug 2004)

How can people be so easily conned into thinking that Mars could EVER be seen as big as the Moon? It boggles my mind that anyone could do this, but sadly it's true. I have received essentially this same email 20 or more times in the last two years (now 3 years as of 08/15/06). It comes from friends and strangers alike. Those friends that understand that this is bogus laugh along with me, and those that don't know the difference we try our best to help them understand the truth about what's really happening.

On August 27, 2003, Mars came closer to Earth than it had been in nearly 60,000 years. At 4:51 am that Thursday morning, Mars had closed the distance to only 34,646,418 miles away from Earth. From that moment onward it began pulling away again. It had also been close in 2001, as well as in 1988, and 1971. To be completely accurate, Mars comes close to Earth about every two years, or every 25.6 months. Mars is coming close to Earth again this November 7th, (2004) when it'll be "only" a little over 43,000,000 miles away. It will be better positioned for northern hemisphere observers all winter long this time.
Mars and Earth both have elliptical orbits around the Sun. However, Earth's orbit is MUCH closer to being truly circular than Mars orbit, and due to this difference in our orbits we keep making these close approaches about every 780 days. This is something that can be called a cycle since it happens with a certain periodicity. We also share a couple other periodicities with Mars. There is a cycle that happens roughly every 15 years when we make an otherwise very close approach to Mars. Another little twist to this 15 year cycle concerns every third or fourth cycle when it's a 17 year period since the last close approach. There are other peculiarities about these cyclical orbital oddities that conspire to give us the rare passages like we had in 2003. But the record from 2003 will not be exceeded for 284 more years until 2287 A.D.!

We have an excellent book in the AOAS library called, "More Mathematical Astronomy Morsels", by Jean Meeus, the world renowned mathematician who tinkers with these ultra-precise measurements of all things astronomical. These complex mathematical formulas that describe the periodicities above may be viewed in his book which paid members may check out if anyone is interested.

But the whole point of this little story is to help everyone understand that when you receive another copy of this bogus and highly misinformed email, just reply to the sender and ask them to check out our AOAS.org website and this article. It's kind of funny, even silly to keep seeing this email message again and again, over and over, but it's a constant reminder of how many people don't understand what's going on in the solar system. This is a condition that AOAS is always trying to help remedy, and we hope that everyone will think of accessing our website for items regarding astronomical objects, reports and happenings. If we can't answer your questions immediately, we'll look up the answer and try to help you understand it for yourself as well.

Next time you hear this hoax, send this to your friends and associates. Check us out the next time you hear that Mars will be as "big as the Moon" or "closer than it's been in 50,000 years". It may just turn out to be total Toro-poopoo, and that's no bull! Aug 28 2010
Email Article To a Friend View Printable Version

The Turbulent Tale of a Tiny Galaxy

NASA Space Placeby Trudy Bell and Dr. Tony Phillips

In the ultraviolet image on the left, from the Galaxy Evolution Explorer, galaxy IC 3418 leaves a turbulent star forming region in its wake. In the visible light image on the right (from the Sloan Digital Sky Survey), the wake with its new stars is not apparent.
Click image for larger view
Next time you hike in the woods, pause at a babbling stream. Watch carefully how the water flows around rocks. After piling up in curved waves on the upstream side, like the bow wave in front of a motorboat, the water speeds around the rock, spilling into a riotous, turbulent wake downstream. Lightweight leaves or grass blades can get trapped in the wake, swirling round and round in little eddy currents that collect debris.

Astronomers have found something similar happening in the turbulent wake of a tiny galaxy that is plunging into a cluster of 1,500 galaxies in the constellation Virgo. In this case, however, instead of collecting grass and leaves, eddy currents in the little galaxy’s tail seem to be gathering gaseous material to make new stars.

“It’s a fascinating case of turbulence [rather than gravity] trapping the gas, allowing it to become dense enough to form stars,” says Janice A. Hester of the California Institute of Technology in Pasadena.

The tell-tale galaxy, designated IC 3418, is only a hundredth the size of the Milky Way and hardly stands out in visible light images of the busy Virgo Cluster. Astronomers realized it was interesting, however, when they looked at it using NASA's Galaxy Evolution Explorer satellite. “Ultraviolet images from the Galaxy Evolution Explorer revealed a long tail filled with clusters of massive, young stars,” explains Hester.

Galaxies with spectacular tails have been seen before. Usually they are behemoths — large spiral galaxies colliding with one another in the crowded environment of a busy cluster. Tidal forces during the collision pull gas and stars of all ages out of these massive galaxies to form long tails. But in IC 3418, the tail has just young stars. No old stars.

“The lack of older stars was one tip-off that IC 3418’s tail isn’t tidal,” says Hester. “Something else must be responsible for these stars”

Hester and eight coauthors published their findings in the June 10, 2010, issue of The Astrophysical Journal Letters. The team described the following scenario: IC 3418 is speeding toward the center of the Virgo cluster at 1,000 kilometers per second. The space between cluster galaxies is not empty; it is filled with a gaseous atmosphere of diffuse, hot hydrogen. Thus, like a bicyclist coasting downhill feels wind even on a calm day, IC 3418 experiences “a stiff wind” that sweeps interstellar gas right out of the little galaxy, said Hester—gas that trails far behind its galaxy in a choppy, twisting wake akin to the wake downstream of the rock in the babbling brook. Eddy currents swirling in the turbulent wake trap the gas, allowing it to become dense enough to form stars.

“Astronomers have long debated the importance of gravity vs. turbulence in star formation,” Hester noted. “In IC 3418’s tail, it’s ALL turbulence.”

To many astronomers, that’s a surprising tale indeed.

See other surprising UV images from the Galaxy Evolution Explorer at http://www.galex.caltech.edu. Kids (and grownups) can play the challenging new Photon Pileup game at http://spaceplace.nasa.gov/en/kids/galex/photon/.
Email Article To a Friend View Printable Version

Astronomy From Your Back Yard - 8/25 to 8/30 2010

By Dave Grosvold

With the Moon just past full this weekend, much of the deep sky will be difficult to observe, and the Moon itself is so bright that much of the detail will be lost in the glare. However, that doesn't mean we have to throw in the towel and stay indoors. There are plenty of celestial targets still available for summer observing.

Jupiter rises well below the Moon about an hour after dark. Although they look close together, Jupiter will be 1,500 times farther from us than the Moon is when they pass on the 26th and 27th. A small telescope or larger binoculars will reveal Jupiter's Galilean Moons. The positions of these moons change from night to night, so a planetarium program or online Galilean Moon Graph utility is essential for identifying these four Jovian satellites.

Uranus is only about 2° west of Jupiter. In a telescope Uranus is only 3.7 arcseconds wide, compared to Jupiter's unusually wide 48 arcminutes. Uranus can be hard to spot. Look for a greenish-white object that is slightly more disk-like than the surrounding stars.

Beginning mid-week, look low in the west-southwest during twilight. Here, Venus forms the bottom of an upside down flat, symmetrical triangle with much fainter Mars and Spica a little higher. By now, Saturn has moved far off to Venus' right or lower right. By Monday, the Venus-Spica-Mars triangle distorts significantly as Venus moves closer to Spica.

Don't forget as well that although the Moon is bright and the deep sky is washed out, The International Space Station still presents a bright target for night sky observers. On Wednesday at 8:30 PM CDT, the ISS should pass high overhead in the SE at an altitude of 50°, shining brightly at magnitude -3.4. The ISS makes several more passes this week, though none is as bright as this one.

On Thursday, look for the ISS at 8:57 PM CDT, as it passes a little less than halfway up the sky (34°) in the NW, reaching magnitude -1.9. On Saturday evening, look for it at 8:17 PM CDT, this time just a bit lower in the NW at altitude 29°. The ISS will shine a bit less brightly at magnitude -1.5. The ISS passes overhead just about every night this week, but these are the brightest.

Also this week, Iridium 3 flares to magnitude -2 in the early morning hours on Friday at 5:21 AM CDT. Look for the Iridium 3 flare at an altitude of 52° in the SW. Iridium 76 flares to a stunning magnitude -8 early on Saturday morning at 5:15 AM CDT, also at 52° altitude in the SW. Sunday evening, Iridium 7 will flare to magnitude -1 at 9:37 PM CDT. Look for it low on the northern horizon at an altitude of 12°. Check the charts at Heavens Above to find out when and which direction to look to catch the both the ISS and Iridium Flares.
Email Article To a Friend View Printable Version

Astronomy From Your Back Yard - 7/21 to 7/28 2010

By Dave Grosvold

This week, the planets Mercury, Venus, Mars, and Saturn continue to mark a nice straight line along the ecliptic, with Mercury in the lead as they sink into the western horizon. Mercury will set very soon after dusk, so you will have to watch carefully as the sun sets to catch it.

On Friday evening, Saturn's largest moon, Titan, is below and to the right of the Ringed Planet this evening. A small telescope will show it at magnitude 9. In the image at left, Titan is above and to the left of Saturn, which is the orientation that matches the mirror-reverse image found in a refracting telescope. Titan orbits Saturn every 16 days, so you can watch it swing from one side of Saturn to the other over a bit more than a two week period. Saturn's Rings, have widened a bit in the last several weeks to 3° from edge-on, even as the planet recedes from Earth.

Jupiter is at magnitude –2.6, in the constellation Pisces this week, and it rises around 12 AM CDT. Jupiter shines as the bright “Morning Star”, high in the southeast in the early morning hours before dawn. Jupiter's smaller, more distant cousin, Uranus is within 3° of the King of Planets at magnitude 5.8. In a telescope, Uranus is a tiny 3.6 arcseconds wide, compared to Jupiter's 44 arcminutes. Uranus will be hard to spot with the Moon reaching its Full phase by 8:37 PM CDT Sunday evening, July 25th.

The latter part of this week, Thursday and Friday evenings are a good time to look at some of the Moon's more prominent features. Most visible in small telescopes are the lunar maria (MAR-ee-ah,) or seas. These are darker areas, or plains on the surface of the Moon that stand out from the surrounding terrain because of their apparent smoothness and lack of albedo, or reflectivity. These maria are actually areas where basaltic lava has been laid on the lunar surface by volcanic activity.

Other prominent features include craters and mountain ranges. Copernicus and Tycho are very prominent craters since they both have relatively high albedos and are surrounded by ray systems, which are the remnants of ejected lunar material due to impacts. Other prominent craters include Ptolemaeus, Plato, Hercules, Atlas, and Endymion. Prominent mountain ranges include Montes Apenninus, Montes Caucasus, Montes Carpatus, and Montes Riphaeus. These mountain ranges are the rough edges that remain from huge, ancient impact craters.

The study of the surface and physical features of the Moon is known as Selenography, which is concerned not with geology so much as lunar mapping and the naming of lunar features. Although there had been earlier attempts to draw maps of lunar features. including a map by Michel Florent van Langren in 1645, the first real lunar atlas was produced by Johannes Hevelius in 1647 and titled Selenographia. Van Langren's map and the name of lunar features had distinctly Catholic origins, where Hevelius' work corresponded to features on Earth and on the Greek and Roman civilizations. If you're interested in Selenography, you should check out Virtual Moon Atlas, which is a great free software download you can use to learn about lunar features.

What's New


No new stories

COMMENTS last 2 days

No new comments

LINKS last 2 weeks

No recent new links

Who's Online

Guest Users: 14

User Functions

Lost your password?

Want It ALL?

Become a card-carrying member of AOAS. Paying dues gives you several advantages over other registered users, including a subscription to the club newsletter, an AOAS.ORG e-mail address, use of club materials, including books and telescopes, and access to the Coleman Observatory facilities. On top of all that, you also qualify for a 20% discount on all books at any Books-A-Million location.

To get your membership application, click here.