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Diamond Bar G Ranch Star Camp - Oct 21 - 23, 2011

  
Satellite view of Diamond Bar G Ranch
Click image to view in Google Maps
The Arkansas/Oklahoma Astronomical Society would like to invite you all to a weekend of observing and fun at the Diamond Bar G Ranch Star Camp located west of Fayetteville, Arkansas. The Star Camp is scheduled to be held the weekend of Oct 21 - 23. While it may conflict with other star parties this fall, this is the only weekend that the Diamond Bar G Ranch will be available for an event of this type that is not during a full moon. Since the RRAC's Burger Burn events will not be held this year, AOAS thought this might make a nice alternative.

The Diamond Bar G Ranch Star Party is a casual event with no registration fees and no planned schedule, other than a pot luck dinner on Friday evening, Oct 21st. We will not be having speakers or any other type of program. The purpose of the event is to do observing in a fairly dark-sky location without a lot of time devoted to other pursuits.

The observing field is wide so there is a clear view to the south and east, with low tree lines to the north and west. The Diamond Bar G Ranch is located in the Bortle Class 2 (blue) Zone, so light pollution is minimal. There are light domes from both Fayetteville in the NE and Van Buren / Fort Smith in the south but they are not obtrusive, and are usually only visible when there is cloud cover. The Milky Way is easily visible with the naked eye on clear nights.
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Astronomy From Your Back Yard - 3/2 to 3/8 2011

By Dave Grosvold

  
The New Moon occurs this week on Friday morning at 2:47 AM CST. Last week we watched the waning crescent moon rise in the eastern sky in the pre-dawn hours, while late this week and early next, we will begin to catch the newly waxing crescent in the western sky starting early Sunday evening. Between now and then, we will be treated to our best dark skies while the Moon is making its monthly pass near the Sun.

  
  
Sirius (α Canis Majoris) shines high in the south during the early evenings in early March. Sirius is the brightest star in our sky at magnitude -1.46. Sirius is known as the Dog Star, due to its position of prominence in the constellation Canis Major, and is actually a binary star system. Sirius A, the larger component, is a white main-sequence star, while Sirius B is its white dwarf companion.

Sirius marks the bottom apex of the Winter Triangle asterism, which is now directly south of us in early evening. The other two vertices of the Winter Triangle are Procyon (α Canis Minoris,) in Canis Minor, and Betelgeuse (α Orionis) in Orion. Over the course of the month of March, we will see the Winter Triangle appear to move further west each evening if you look at about the same hour of darkness. Don't forget — we switch to Daylight Saving Time on March 13, so the same hour of darkness occurs about an hour and a half later by the end of the month. So if you look at 7:30 PM tomorrow evening, by the end of the month it will be about 9:00 PM before you will see the sky reach the same darkness level.

Jupiter is sinking down the western sky this week, just a bit lower each day. By Tuesday evening early next week, Jupiter sets by 8:00 PM CST, so early evening is the best time to catch it. Still brighter than Sirius by quite a bit at magnitude -2.1, it is not nearly as bright as it was in late December. In the meantime, Venus at magnitude -4.1 is almost twice as bright, rising in the east-southeast before dawn this time of year. Since they are not both in the sky together, it is difficult to compare the two without instrumentation.

On Sunday evening, look low in the western sky for a very thin waxing crescent Moon almost due west, about 6° to the right and slightly higher than mighty Jupiter (6 degrees would be about 4 finger widths at arm's length.)

  
Starting early next week, Mercury is a challenging evening object, and is now very low in bright twilight below Jupiter. Starting Monday, very early in the twilight (about 6:15 PM CST,) if you have a very clear sky and you can find an observing location with a low, clear western horizon (like the eastern shore of a lake,) Look close to the horizon with a pair of binoculars directly below the now-thicker waxing crescent Moon and you may find Mercury as a tiny pin-prick of bright light against the glowing sunset background. Mercury will set between 6:30 PM and 6:45 PM CST, so you don't have a lot of time to look. The visibility of objects in bright twilight is greatly exaggerated in the accompanying image, but you get the idea.

Saturn rises in Virgo around 8 PM CST, but it's best to wait to observe it with a telescope until it gains high altitude, clearing the bad seeing due to the thicker atmosphere at the horizon. Saturn is highest in the south around 2 AM CST. Spica (α Virginis,) slightly fainter, shines about 9° below Saturn all evening and into the early morning hours. Saturn's rings are tilted at about 9.7° with respect to Earth right now, so they should easily be visible in small telescopes. Look for Saturn's moons while you have it centered in your eyepiece.

The International Space Station (ISS) will make several bright passes over our area early next week. Look for the ISS to pass low in the NE (from the NNE to the NE) at an altitude of 10° at 7:05 PM CST on Sunday. This pass will be at magnitude -1.0, which is about the same as Regulus in Leo. On Monday evening, the ISS passes over our northern sky at an altitude of 25° at 7:31 PM CST. This time, it will reach magnitude -2.3, or slightly brighter that Venus. Then Tuesday evening, the ISS passes high over our northwestern sky at 7:56 PM, reaching an altitude of 50° and a magnitude of -2.8, which will be brighter than anything else in the sky at that hour.
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Astronomy From Your Back Yard - 2/16 to 2/22 2011

By Dave Grosvold

  
Aurora over Fairbanks, Alaska, October 26, 2007
Photo by Mila Zinkova
Unfortunately, the chances are much lower for seeing the Aurora Borealis or "northern lights" than were reported earlier. The recent coronal mass ejection (CME, or solar flare) from Sunspot 1158 will hitting our planet's magnetic field for the next 24 - 48 hours. The chances of seeing an aurora at high latitudes (50°N,) are now down to 45%, with much slimmer chances (less than 5%,) that they will reach as low as 35°N, the latitude of NW Arkansas. There will be more chances over the next few years though as the number of CMEs is now on the increase.

  
NASA Photo
However, for another unusual treat, sky observers stand a good chance of viewing the Zodiacal Light from Fort Smith and NW Arkansas during the last half of this month. Starting on Saturday evening, find a dark sky location with a clear western horizon, wait for your eyes to dark-adapt, and be prepared to start looking west along the horizon about an hour and a half after sunset. If the zodiacal light is visible, you will see a vague, huge pyramid of softly glowing light sloping toward the south along the line of the ecliptic. Don't give up if you don't see it the first time you go out. This phenomenon will occur in the evenings from Saturday over the next 10 days or so.

  
On Thursday evening, look to the left or lower left of the Moon after dark for Regulus. Farther left of them is Gamma Leonis, not much fainter than Regulus. Look farther to the Moon's lower right for orange Alphard.

The Full Moon occurs this week at 2:36 AM CST Friday morning. On Friday evening, look for Regulus about a fist-width above the Moon. Regulus marks the bottom-right end of the Sickle (actually the bottom of the Sickle's handle.) The Sickle is an asterism in the constellation Leo. Also on Friday evening, at 6:20 PM CST, look straight to the north toward Polaris to catch Iridium 13 as it flares to an intensely bright magnitude -8.0.

At dusk this week, Jupiter shines brightly in the west-southwest and then sets in the west by around 8:00 PM CST. The best time to view it is in late twilight while it's still high. The South Equatorial Belt continues to re-form. Uranus has drifted away from Jupiter to the west and they are now separated by about 6°. They will continue to drift apart as the month progresses.

  At around 10:30 PM CST this week, Saturn rises in Virgo. By the end of the month, it will rise about an hour earlier. Last month Saturn was less than 8° from Spica, but now Saturn is moving away since it's reached a place in its orbit where it displays apparent retrograde motion. By 3:30 AM CST, Saturn culminates (passes its highest point in the night sky.) Saturn's rings are 10° from edge on, their maximum for this year.

  
On Monday morning, Feb 21, Saturn and Spica form an equilateral triangle with the Moon in the pre-dawn darkness of the southwester sky. Monday evening at 7:34 PM CST gives us another chance to catch an Iridium Flare, this time Iridium 39, in the south-southeast, also at a brilliant magnitude -8.0.

In the east all this week, an hour or so before dawn while the sky is still fully dark, Venus rises and climbs until it is lost in the glow of sunrise. Venus has lost a bit of its luster, dropping from magnitude -4.3 to -4.1 while its phase increases to more than 70% lit, but still remains the brightest object in the morning sky — our "Morning Star". How can this be? Venus is drawing further away from Earth as its phase increases, so the apparent brightness is actually lower.

Unfortunately, Mercury, Mars, and Neptune are hidden behind the glare of the Sun this week.

The International Space Station (ISS) will also make several passes overhead this week that will be brighter or equal to magnitude -2.5. Saturday evening, at 6:58 PM CST, the ISS at magnitude -2.8, will pass low in the SE at an altitude of 34°. On Sunday at 7:14 PM CST, the ISS will pass mid-way up the NW sky at altitude or 49° also with a brightness of magnitude -2.8. Then on Tuesday evening, it will reach a magnitude of -2.5, again passing mid-way up the sky (42°)in the NW at 6:30 PM CST.
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Astronomy From Your Back Yard - 1/5 to 1/11 2011

By Dave Grosvold

  
Happy New Year! Things are “looking up” in backyard astronomy — at least for the remainder of this week. With the skies relatively clear until the weekend, and the waxing crescent Moon, the resulting sky glow is not bright enough to present much of a problem for evening sky watchers.

  
One of the most spectacular sights to be had for amateur astronomers on these cold clear winter evenings is the central region of the constellation of Orion. This region is home to large bright nebulae and open clusters easily visible in a small telescope or binoculars. I mentioned M42, the Great Orion Nebula which is the brightest deep sky object in this region last year at this time.

Two objects in this area besides M42 are special treats. The first, NGC 1977, is known as the Running Man Nebula. NGC 1977 is a beautiful blue emission nebula with a dark reflection nebula inside it. Because of the reflected glow from brighter and larger M42, the darker parts of NGC 1977 reflects the colorful hues of M42 and imbue it with a mysterious, ghostly quality. Some have come to refer to NGC 1977 as the Ghost Nebula for this reason.

  
The second object, NGC 1981, is a large open cluster just above NGC 1977. NGC 1981 is a beautiful sprinkling of 10 or 11 bright stars in the Orion-Cygnus Arm of the Milky Way Galaxy, peppered with a background of the much more distant stars of other regions of the Milky Way. All of the stars in the cluster and the two nebula mentioned above are relatively close neighbors of the Solar System, at a mean distance of only about 700 light years from Earth. This makes it one of the nearest star forming regions we have available for study.

Two other deep sky objects in this region surround the star known as Alnitak, or Zeta Orionis (ζ Ori.) This triple star system, the easternmost star in the Belt of Orion, is surrounded by two well-known faint emission nebula, B33, the Horsehead Nebula, and NGC 2024, the Flame Nebula. These are normally not visible in small telescopes or binoculars, but they are a popular target for astro-imagers.

  
By 7:30 PM CST Wednesday evening, the Moon has set and the Winter Triangle is well up in the east-southeast, consisting of Betelgeuse in Orion's leftmost corner, bright Sirius in Canis Major below and to the right, and Procyon in Canis Minor to the left of these two. The Winter Triangle is brighter and more colorful than it's well-known summer counterpart. An even larger asterism, the Winter Hexagon, includes Procyon and Sirius, along with four other bright, colorful stars in the eastern evening sky: Rigel in Orion; Aldebaran in Taurus; Capella in Auriga; and Pollux in Gemini.

  
The brightest "star" in the evening sky this week is NOT a star, but a planet! As the current Evening Star, Jupiter still shines at magnitude -2.3 in Pisces, high in the south above Fomalhaut in Piscis Austrinus. Jupiter is receding from us as Earth begins to round the far side of the Sun from Jupiter, so it appears only 38 arcseconds wide. However, Jupiter is still wide enough to see the South Equatorial Belt re-forming and the transits of the Great Red Spot in a small-to-medium telescope. Uranus is now very close to Jupiter, just 0.6° to the west of the larger planet. Both planets should be close enough so they are both visible in the same field of view in a small telescope when using a medium power eyepiece. A third planet, Neptune, is also still visible in the early evening southwestern sky west of Fomalhaut, on the border between Aquarius and Capricornus. This one is much harder to spot and requires a small telescope or binoculars.

Bright Saturn rises about 30 minutes past midnight this week. By 3:30 AM CST, Saturn is in a perfect position for viewing, high in the southeastern sky in Virgo. That puts it above the thick lower atmosphere long before the sky glow begins in the east as the rising Sun approaches the horizon. The rings are tilted now at about 10°, widening as spring approaches. The rings haven't been this wide since 2007.

Later in the morning this week, very near dawn, Venus shines in the southeastern sky. Though very bright at magnitude -4.3, viewing Venus, in a telescope reveals itself to be only half-lit. Venus is very nearly at it's greatest elongation from the Sun. Venus will begin to grow gibbous in the coming months, while shrinking in diameter as it begins to swing around the far side of the Sun in its faster orbit.

Mercury, too, will be relatively bright at magnitude 0, low in the southeastern sky just before dawn. Notice fainter Antares in Scorpius and the rest of the starry background of the Milky Way, rising in the east before dawn as the winter season marches on.
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Astronomy From Your Back Yard - 12/15 to 12/21 2010

Backyard Astronomy Extra - Total Lunar Eclipse!

By Dave Grosvold

  
  
On Saturday evening, look just to the left of the Moon a mere 2° for the delicate Pleiades star cluster. The Pleiades is a beautiful, fairly tight open cluster in Taurus that was used by Native American tribes to test the eyesight of their scouts. See if you can see more than 5 stars in the Pleiades with the naked eye. If so, then you would have qualified as a scout in the Old West. This week, you may need to use binoculars to see the Pleiades due to the overwhelming glare of the waxing gibbous Moon.

Below the Pleiades by about a fist-width is orange Aldebaran. Aldebaran is part of the Hyades star cluster, an open star cluster in Taurus that looks to most like a small “V” laying on its side in the eastern sky. Far off to the left of the Hyades shines brighter yellow Capella. On Sunday evening, the Moon is to the left of the Hyades, and just to the left of a small star named Tau Tauri (τ Tau). By Monday evening, the Moon has moved just to the left of Zeta Tauri (ζ Tau.) By now, you've realized that the Moon has taken three nights to pass from one end of Taurus to the other.

  
   Click image for larger view
But the REAL highlight of the week is still yet to come. On Tuesday morning, the Full Moon occurs right at the mid-point of a total lunar eclipse! Make plans now to see this last lunar eclipse of the year. The eclipse begins just after midnight in the early-morning hours of Tuesday, December 21, 2010.

  
The eclipse reaches its mid-point at about 2:17 AM CST Tuesday morning. The Moon will be shining brightly very high in the early-morning sky during the eclipse, in the south-southeast. By the time it reaches mid-eclipse, the Moon will be high in the southwest, and will drop into the western sky by the end of the eclipse at 4:01 AM. The best way to view this eclipse is with a pair of binoculars or a small telescope.

The dim Little Dipper (Ursa Minor) hangs just about straight down from the North Star by about 9:30 PM all this week, as if it was hung from a hook on the wall of the sky. The brighter Big Dipper (Ursa Major) is rearing upward on its handle low in the north-northeast. You can easily find Polaris, (or the North Star,) by using the two end stars of the bowl of the Big Dipper.

  
Venus shines with a brilliant light in the southeastern sky this week before and during dawn. Venus now rises about two hours before the first light of dawn (about 3:45 AM CST,) and rises to an altitude of about 33° before getting lost in the glare of the rising Sun. While it's till dark, look for fainter Spica well to Venus' upper right, and for Saturn above Spica. Look off about twice that distance to Venus' upper left for Arcturus. Saturn's rings have widened to 10° from edge-on, and present an interesting sight along with its larger moons in a small telescope.

Of course, Jupiter shines almost as brilliantly as Venus during the evening, high in the south-southwest. The long-absent South Equatorial Belt continues to re-form, as dark markings spread east and west around the planet from a storm that broke out in the SEB's latitude about a month ago.

Uranus is still within 2° to the left of Jupiter, and can be spotted in a small telescope. Have a look at Jupiter first, and then look for an object to the upper left of Jupiter with about the same brightness as Ganymede. Ganymede is about magnitude 5.36 where Uranus is very slightly dimmer at about magnitude 5.45. Don't confuse Uranus with the star 20 Pisces (20 Psc,) which is also the same magnitude, but it is somewhat redder, and about halfway in between Jupiter and Uranus.

Neptune is much dimmer at magnitude 7.9, and is still up in the southwest in Capricornus after dark. Look for 5th-magnuitude Mu Capricorni next to it.
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Astronomy From Your Back Yard - 12/08 to 12/14 2010

By Dave Grosvold

  
If you can get out and observe in the two hours before the coming of dawn this week, Venus blazes in the southeast, even after sunrise. Venus is still at its highest luminosity, at magnitude –4.8 and nearly as high as it gets. Can you watch Venus past sunrise with your naked eye? Look for much fainter Spica to Venus' upper right (about 20°,) and for Saturn about 20° above Spica.

In the evenings this week, Mercury remains in view low about the southwest horizon during twilight. Look about 40 minutes after sunset. Mercury fades from magnitude –0.4 to +0.1 this week.

  
On Wednesday Dec 8th, by 7 or 8 PM CST, bright Capella in Auriga is high in the east-northeast. To its right in the east is the Pleiades (M45), or Seven Sisters, and below it is ruddy Aldebaran in Taurus. Below Capella lie Castor and Pollux, the heads of the twins of Gemini. It will be important to know the location of these twins early next week.

As soon as it gets dark on Thursday evening, look for the waxing crescent Moon in the southwest. To the right of the Moon about 7°, is tiny Alpha Capricorni (α Cap.) If you have sharp vision you can barely see that this is a very close double star. You can resolve it easily in binoculars.

Jupiter still shines brightly this week at magnitude -2.5. Just after dusk on Friday evening look far to the lower right of Jupiter for the waxing crescent Moon. Look below Jupiter to the lower left of the Moon for Fomalhaut (FOAM-a-lout), in Piscis Austrinus, sometimes called “the Autumn Star.”

By Saturday evening, the nearly first-quarter Moon this evening forms a roughly equilateral triangle with bright Jupiter to its upper left and Fomalhaut to its lower left. The Moon reaches First Quarter at 7:59 AM CST, on Monday December 13th.

  
Monday, December 13th near midnight marks the start of the peak of the Geminid meteor shower for this year, and for most observers, it is the highlight of the week. The peak of the shower continues through the night into the morning hours of Tuesday, December 14th. The name “Geminids” refers to the fact that the radiant for this meteor shower appears to come from the heart of the Twins of Gemini. When meteors are traced back to their apparent origin, the paths they followed all converge at a point on the sky known as the radiant.

From now until December 13th, hourly rates increase until a peak of 50-80 meteors per hour is attained. The rate then tapers off until the last Geminids on December 18th, when the rates fall to one every hour or so. Meteor showers occur all the time, but most are very weak. So there may be stray meteors that are not part of the Geminids during this time as well. When you see a meteor, how do you know if it's a Geminid? Trace the path of the meteor back to its apparent origin. If that origin ends up being in Gemini or close to it, then it's probably a Geminid.

The best way to observe the Geminid Meteor Shower is lie back on a chaise lounge with a clear view of the sky toward Gemini. This time of year, be sure to dress warmly, get a thermos of coffee or hot chocolate, and maybe even throw on a blanket or two. As you lie there, look high up and all around the sky, and don't focus in just one place.

  
Meteors will appear all over the sky, but the majority will appear to have come from the direction of Gemini, so we face the chaise lounge that way. But we scan from overhead down to about 30° up the sky. We also scan off to the right, and then to the left, looking at the big picture rather than focusing in any one area. Don't discount the sky opposite Gemini, either. Meteors can be seen all over the sky. See if you can count the number of meteors you see in an hour's time, and note the time of night.

On a historical note, the Geminid meteor shower appeared suddenly in the latter part of the 1800's. R. P. Greg of Manchester in the UK first noted several meteors that had a radiant in Gemini in December of 1862. Several other observers independently discovered the same activity the same year from the United States.

Early observations in the late nineteenth century reported the hourly rates at about 14 per hour. As the century waned, the hourly rate seemed to increase to about 23 per hour, with many more bright meteors. These rates have continued to increase throughout the 20th century, averaging about 50 per hour mid-century with the peak rate reaching an average of 80 per hour in the 1980s. The peak hourly rate continues to remain at 80 per hour today. Scientists now think the Geminids are tied to the passage of an asteroid (or minor planet,) 3200 Phaethon, in our solar system across Earth orbit every few years. The Earth passes through the dust and debris left in its wake, creating tiny meteors in our upper atmosphere as we pass.
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Astronomy From Your Back Yard - 12/01 to 12/07 2010

By Dave Grosvold

  
     
  
On Friday morning, about 1/2 hour before dawn, look for a razor-thin crescent Moon far below Venus in the southeastern sky. Venus is at its maximum brightness magnitude –4.9, and as is commonly known as the “Morning Star”. Far above Venus is Spica in Virgo, and above that, Saturn at magnitude +0.9. Saturn's rings are 9° or 10° from edge-on now, and early dawn is the best time to observe the ringed planet all this week.

  
Early in the evening all week, the constellation Cassiopeia floats very nearly directly overhead when you face north. Look for an M-shaped grouping of stars high above you for Cassiopeia. About halfway from Cassiopeia to the horizon lies Polaris, the North Star. Polaris is the brightest star in the otherwise dim constellation of Ursa Minor, commonly known as the Little Dipper.

Far below Polaris, and very nearly below the horizon, lie the upper-most stars of the Big Dipper asterism, part of the constellation of Ursa Major. The tail of Draco wends its way between Polaris and the stars of Ursa Major. This far south, you may not even be able to spot the stars of Ursa Major without finding a nearly flat horizon clear of obstructions.

Jupiter shines high in the south to southwest during evening, the brightest star-like point in the evening sky. Jupiter's missing South Equatorial Belt is finally starting to re-group, becoming barely visible as dark material spreads from a series of telltale bright storm spots that appeared three weeks ago.

On Friday evening, Jupiter's moon Europa reappears from eclipse out of Jupiter's shadow around 7:30 PM CST. Watch and wait for a few minutes, and a small telescope will show it gradually become visible just east of the planet.

  
Later in the evening, look to the east to see the starry harbingers of Winter, orange Aldebaran in Taurus, fiery red Betelgeuse and blue-white Rigel in Orion, bright yellow Capella in Auriga, the TwinsCastor and Pollux in Gemini, brilliant blue-white Sirius, the brightest star in the sky — and the brightest in Canis Major. Don't forget the white binary star system Procyon in Canis Minor, considered the seventh brightest in the sky. Betelgeuse, Sirius, and Procyon make the three vertices of the Winter Triangle asterism.

Mercury, at magnitude –0.4 is now at the best time for observing its current evening apparition. Still, it's quite low on the horizon, and a challenge. Look for it in mid-twilight just above the southwest horizon.

New Moon occurs on Sunday, December 5th at 11:36 AM CST, so both Saturday evening and Sunday evening will be good times to observe deep-sky objects (those outside our Solar System.)

This week is a great time to see Iridium Flares, both in the morning and evening. At 6:02 PM CST on Sunday, December 5th, Iridium 63 flares to magnitude -0 low in the western sky at an altitude of 11°. Just a few minutes later at 6:37 PM CST, Iridium 49 flares to magnitude -2 at an altitude of 30° in the south. Early Monday morning, at 7:01 AM CST, Iridium 46 flares to an absolutely brilliant -8 magnitude high up in the sky at 71° altitude. Look for it at azimuth 339° (in the NNW.) This is the brightest flare that will occur over the coming week.

Monday evening, Iridium 65 and 66 put on a show at 5:47 PM and 5:56 PM CST, respectively. Iridium 65 will flare to magnitude -1 and Iridium 66 will reach magnitude -2. Both satellites will be low (at altitudes of 13° and 10°) in the Western sky. On Tuesday morning at 6:55 AM CST, we see Iridium 46 reach a fairly bright magnitude -5, pretty high up at an altitude of 69° in the NNW, and then Tuesday evening at 5:41 PM CST, Iridium 68 also flares to magnitude -5 low at an altitude of 14° in the Western sky. You can find out more about these at the Heavens Above web site.
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Astronomy From Your Back Yard - 11/17 to 11/23 2010

By Dave Grosvold

  
Unfortunately, business travel demands have kept me away from this column for a couple of weeks. It's good to be back! Well, it looks like there will be some clear skies and great opportunities for night-time sky watching Thursday through Sunday this week. To get a better idea how the night sky viewing will be for the next two evenings, check out the Fort Smith Clear Sky Chart. This chart will tell you how dark the sky will be, when you can expect cloud cover during the night, and what transparency and seeing conditions are expected.

  
On Wednesday evening, Jupiter will be slightly higher and about 20° to the right of the waxing gibbous Moon. The Moon reaches the Full phase on Sunday, November 21 at 11:28 AM CST. As a result, it will be a bright beacon in the night sky all week, washing out all but the brightest stars and planets. There will be early-morning dark skies late this week (Thursday & Friday,) as the Moon sets at about 3:00 AM CST on Thursday morning, setting about an hour later each morning until later in the week when it remains visible the entire night.

The bright star Vega in the constellation Lyra remains the brightest star in the west-northwest these evenings. The brightest star higher above it is Deneb in the constellation Cygnus. To the left of Vega lies the third member of the Summer Triangle, Altair, in the constellation Aquila. Both the cool crisp air and the Summer Triangle low in the western sky are sure signs of approaching winter.

For a challenge this week, use binoculars to scan for Mercury very low in the southwest less than a half hour after sunset. Mars is less than 2° to Mercury's upper right. If you place Mercury in the lower left of the field of view, you should be able to detect fainter Mars above and to the right.

By 9:00 PM CST Saturday, November 20th, the constellation Orion has risen in the east-southeast. Look for it far below this evening's high, bright Moon. The three unmistakable belt stars in Orion will be lined up vertically, with the bright blue-white star Rigel on the right, and fiery-red Betelgeuse on the left.

  
Halfway between Betelgeuse and the Moon is another bright red star, Aldebaran, in Taurus. Draw an imaginary line from the Moon down through Aldebaran to Betelgeuse, and then imagine a line perpendicular to the first one, to the left of Adebaran you should see the bright yellow star Capella, in the constellation Auriga.

  
On Sunday evening, the Full Moon passes just below the Pleiades (M-45,) an open cluster in the constellation Taurus. At closest approach the Moon is just slightly more than 4° from the center of the Pleiades, or just over the width of two fingers held at arm's length.

This week, Venus is rising ever higher at dawn in the east-southeast. Look a little above it or to its upper right for much-fainter Spica in Virgo. Look higher (about 16°) above it for Saturn. Saturn's rings have widened to a tilt of about 9° from edge-on. The best time for observing Saturn with a telescope is about an hour before sunrise, or about 6:00 AM local time, when the planet will be above the “muck” -- the haze and turbulence found close to the horizon.

You may also be able to catch a couple of bright Iridium Flares this week. Iridium 41 flares to -6 magnitude at 4:51 AM CST on Thursday morning. Look for it in the south at an altitude of 21°. Then on Sunday evening at 5:58 PM CST, you can catch Iridium 66 flare to magnitude -7 in the south at an altitude of 33°. Early on Monday morning, Iridium 62 flares to magnitude -4 nearly overhead at an altitude of 59° in the north-northwest. There are a several other chances to catch Iridium Flares, this week albeit at dimmer magnitudes. Be sure to check the web site at Heavens Above for times and positions.
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Astronomy From Your Back Yard - 10/27 to 11/2 2010

By Dave Grosvold

  
This week the Moon is well on its way toward Last Quarter, which occurs at 7:47 AM Saturday, Oct 30th. Forecasts call for several clear evenings into the weekend, an excellent opportunity for a little night sky observing -- especially since the Moon won't rise until after 11:00 PM CDT.

  
NASA, ESA, AURA/Caltech, Palomar Observatory
During the latter part of the week, yellow-bright Capella is shining in Auriga, well up in the northeast by mid-evening. Look off to its right in the east for the Pleiades, or Seven Sisters.

The beautiful Pleiades (PLEE-ah-deez,) star cluster is also known as Messier 45 (M45), one of the original 103 objects Charles Messier catalogued in 1771 as objects to avoid while comet hunting, which was his main passion. Messier's list became better known to history as the first list of interesting non-stellar objects in the night sky.

The Pleiades are probably the most well-known star cluster visible to the naked eye. A group of young, blue-hot stars surrounded by nebulosity, the cluster is thought to be less than 100 million years old. By contrast, the Sun is thought to be more than 4.6 billion years old. In Japan, the Pleiades cluster is known as Subaru, and is graphically depicted as the corporate logo for the automaker of the same name.

Below the Pleiades, spaced by about a fist-width at arm's length, is the orange giant Aldebaran, the brightest star in the constellation Taurus. A close neighbor, Aldebaran lies only about 65 light years distant from our Solar System. Aldebaran (Al-DEB-a-ran) means “the follower”, presumably because it appears to follow the Pleiades. For the Seris of northwestern Mexico, Aldebaran is there to provide light for the seven women giving birth (the Pleiades.)

  
Every year for several days around October 29th, the bright star Arcturus, in Boötes, takes a special position sparkling in the fading twilight low on the west-northwestern horizon. This position marks the spot where, months earlier in June and July, the Sun stood at the exact same time of the evening. Then, the summer daylight was still strong in the evenings, now the autumn light is fading and this much smaller, scintillating gem is all that remains in the west, the Ghost of the Summer Sun, marking the mid-point of autumn.

Mars is still hanging around very low in the southwest after sunset as well. Use binoculars to scan for it early in twilight. Don't confuse Mars with Antares, which is off to Mars' left and just a tiny bit brighter. The name Antares comes from Ancient Greece, so named because the star can easily be mistaken for Mars. Antares literally means "holds against Ares" (Ares is also known as Mars in Roman mythology.)

  
Jupiter still shines high in the southeast between Pisces and Aquarius rising high into the south-southeast as the evening wears on. Right now, it is by far the brightest star-like point in the sky. Jupiter continues to appear a big 47 or 48 arc-seconds wide in a telescope or binoculars.

Once again, the tiny black shadows of two of the Galilean Moons, Europa and Ganymede, fall on Jupiter's face from 11:16 PM CDT Saturday evening to 1:59 AM CDT Sunday morning. These can only be caught with the aid of a small telescope -- binoculars won't do.

Saturn is visible in Virgo, low in the east in early dawn. The best time to try observing it with a telescope is in moderately bright morning twilight, perhaps an hour before sunrise, when it will be less blurred by the low-altitude atmospheric mess. Saturn's rings have opened to 7° or 8° from edge-on, and so are more prominent than they were just a few months ago.

Uranus is still within 3° east of Jupiter. Neptune, in Capricornus, is high and almost due south at about 9:00 PM CDT.
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Astronomy From Your Back Yard - 10/20 to 10/26 2010

By Dave Grosvold

  
  
The Full Moon occurs this week at 8:37 PM, CDT on Friday, October 22nd. The nearly full Moon washes out the sky for the entire night on Wednesday and Thursday evenings, since it will rise before sunset and will not set again until nearly dawn. However, the Moon rises about 30 minutes later each evening, so by Tuesday, October 26th, the waning gibbous Moon will not be in the sky until after 9:00 PM CDT.

Although both the bright glow of the Moon and the weather forecast don't look favorable for astronomical observing this week, you may still be able to catch a glimpse of Comet 103P/Hartley in binoculars or a small telescope. Look for it in the constellations Auriga and Gemini in the eastern sky at about 12:30 AM CDT. Whether you'll see the comet or not depends to a great degree on the quality of the sky when you make the observation.

This week, the Big Dipper asterism in Ursa Major lies level in the north-northwest after dusk, quite low, far below the bowl of the much dimmer Little Dipper (Ursa Minor).

On Thursday evening, the Great Square of Pegasus asterism is straight above the waxing gibbous Moon after dark. The Great Square is tipped on one corner and somewhat larger than your fist held at arm's length. The Great Square is actually part of two constellations - its namesake Pegasus, and Andromeda.

Mars is getting dimmer at magnitude 1.5, which is still fairly bright as astronomical objects go. Mars continues to linger very low in the southwest right after sunset.

  
Even with the moon glow, bright Jupiter is an easy target in the constellation Picses. Jupiter is still within its first month past opposition, and has just passed a very close approach to Earth, — perfectly positioned for viewing mid-way up the east-southeastern sky, reaching its highest point at about 11:00 PM.

On Saturday, October 23rd, see if you can catch the tiny black shadows of both Ganymede and Europa as they pass across Jupiter, from 8:40 to 10:04 PM CDT.

Saturn is back as a morning planet, just emerging from the sunrise glow. Look for it in the constellation Virgo, very low in the east about an hour before sunrise. It's within 1° of fainter Gamma Virginis.

Neptune, at magnitude 7.8 in Capricornus, is still highest in the south about an hour after sunset. With the expected sky conditions this week, Neptune will be a difficult target. You will need a small telescope to catch it.

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