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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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Solar System Size Surprise

NASA Space Placeby Dr. Tony Phillips

  
This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Image credit: NASA/JPL-Caltech.
Click image for larger view
News flash: You may be closer to interstellar space than you previously thought.

A team of researchers led by Tom Krimigis of the Johns Hopkins University Applied Physics Laboratory announced the finding in the June 2011 issue of Nature. The complicated title of their article, “Zero outward flow velocity for plasma in a heliosheath transition layer,” belies a simple conclusion: The solar system appears to be a billion or more kilometers smaller than earlier estimates.

The recalculation is prompted by data from NASA’s Voyager 1 probe, now 18 billion kilometers from Earth. Voyagers 1 and 2 were designed and built and are still managed by NASA’s Jet propulsion Laboratory. Aging but active, the spacecraft have been traveling toward the stars since 1977 on a heroic mission to leave the solar system and find out what lies beyond.

To accomplish their task, the Voyagers must penetrate the outer walls of the heliosphere, a great bubble of plasma and magnetism blown in space by the solar wind. The heliosphere is so big, it contains all the planets, comets, and asteroids that orbit the sun. Indeed many astronomers hold that the heliosphere defines the boundaries of the solar system. Inside it is “home.” Outside lies the Milky Way. For 30+ years, the spacecraft have been hurtling toward the transition zone. Voyager 1 is closing in.

Much of Voyager 1’s long journey has been uneventful. Last year, however, things began to change. In June 2010, Voyager 1 beamed back a startling number: zero. That’s the outward velocity of the solar wind where the probe is now.

“This is the first sign that the frontier is upon us,” says Krimigis.

Previously, researchers thought the crossing was still years and billions of kilometers away, but a new analysis gave them second thoughts. Krimigis and colleagues combined Voyager data with previously unpublished measurements from the Cassini spacecraft. Cassini, on a mission to study Saturn, is nowhere near the edge of the solar system, but one of its instruments can detect atoms streaming into our solar system from the outside. Comparing data from the two locations, the team concluded that the edge of the heliosphere lies somewhere between 16 to 23 billion kilometers from the sun, with a best estimate of approximately 18 billion kilometers.

Because Voyager 1 is already nearly 18 billion kilometers out, it could cross into interstellar space at any time — maybe even as you are reading this article.

“How close are we?” wonders Ed Stone, Caltech professor and principal investigator of the Voyager project since the beginning. “We don't know, but Voyager 1 speeds outward a billion miles every three years, so we may not have long to wait.”

Stay tuned for the crossing.

For more about the missions of Voyager 1 and 2, see http://voyager.jpl.nasa.gov/. Another Voyager project scientist, Merav Opher, is the guest on the newest Space Place Live cartoon interview show for kids at http://spaceplace.nasa.gov/space-place-live.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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New GOES-R to Give More Tornado Warning Time

NASA Space Placeby Dauna Coulter and Dr. Tony Phillips

  
This GOES image shows the storms that spurred the intense April 27 tornado outbreak in the southern U.S. Animation showing the development of weather can be seen at http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=50347.
Click image for larger view
So far this spring, more than 1,400 tornadoes have struck the U.S. Some of them have cut jaw-dropping trails of destruction across the countryside and, tragically, across inhabited communities, too. Hundreds of lives have been lost in the onslaught.

Throughout the season, the National Weather Service has routinely issued tornado alerts. In the case of the Alabama tornadoes of April 27th, forecasters warned of severe weather five full days before the twisters struck. Because they couldn’t say precisely where the twisters would strike, however, many of their warnings went unheeded.

“If people get a hurricane warning, they often evacuate the area,” notes NOAA's Steve Goodman. “But we react differently to tornado warnings.”

Perhaps it’s because tornadoes are smaller than hurricanes, and the odds of a direct hit seem so remote. Recent pictures from Tuscaloosa, Alabama, and Joplin, Missouri, however, show the perils of playing those odds. Goodman believes that more precise warnings could save lives.

To fine-tune tornado warnings, NOAA will soon launch the first in a series of next-generation weather satellites — GOES-R (Geostationary Operational Environmental Satellites-R series). The spacecraft is brimming with advanced sensors for measuring key ingredients of severe weather including winds, cloud growth, and lightning.

“GOES-R will be the first geostationary spacecraft to carry a lightning sensor,” says Goodman, the GOES-R Program Senior Scientist. “Studies show that sudden changes in the total lightning activity correlate with storm intensity &madash; and with tornadoes.”

The lightning mapper will detect and map not only cloud-to-ground lightning, but also bolts within and between clouds. The kind of cloud-to-ground lightning we see from our front yards accounts for only 15-20 percent of total lightning. To get a clear idea of a storm's intensity, meteorologists need to know about all the lightning — a view GOES-R can provide.

All by itself, the lightning mapper will provide 7 minutes more lead time in tornado warnings, according to Goodman. GOES-R’s state-of-the-art instruments will also improve long-range forecasts.

“The satellite's Advanced Baseline Imager (ABI), for instance, will provide a much clearer picture of clouds,” says NOAA research meteorologist Tim Schmit. Compared to lesser instruments already in orbit, ABI can better detect super-cold “overshooting tops,” evidence of enormous energy and upward velocity that correlate with subsequent severe weather.

“Accurate advanced notice of high-risk tornadic conditions can cue officials to close schools and businesses even before tornadoes are actually detected,” says Schmit.

Forecasters doubt tornadoes can ever be predicted with 100% accuracy. The twisters are just too capricious. GOES-R, however, is a step in the right direction.

Find out more about GOES-R’s unprecedented capabilities at http://www.goes-r.gov. Young people can learn more about tornadoes and all kinds of other weather at http://scijinks.gov.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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Finding Planets among the Stars

NASA Space Placeby Dr. Tony Phillips

  
Exoplanets are easier to see directly when their star is a dim, red dwarf.
Click image for larger view
Strange but true: When it comes to finding new extra-solar planets, or exoplanets, stars can be an incredible nuisance.

It’s a matter of luminosity. Stars are bright, but their planets are not. Indeed, when an astronomer peers across light years to find a distant Earth-like world, what he often finds instead is an annoying glare. The light of the star itself makes the star's dim planetary system nearly impossible to see.

Talk about frustration! How would you like to be an astronomer who's constantly vexed by stars?

Fortunately, there may be a solution. It comes from NASA's Galaxy Evolution Explorer, an ultraviolet space telescope orbiting Earth since 2003. In a new study, researchers say the Galaxy Evolution Explorer is able to pinpoint dim stars that might not badly outshine their own planets.

“We've discovered a new technique of using ultraviolet light to search for young, low-mass stars near the Earth,” said David Rodriguez, a graduate student of astronomy at UCLA, and the study's lead author. “These M-class stars, also known as red dwarfs, make excellent targets for future direct imaging of exoplanets.”

Young red dwarfs produce a telltale glow in the ultraviolet part of the electromagnetic spectrum that Galaxy Evolution Explorer can sense. Because dwarf stars are so numerous — as a class, they account for more than two-thirds of the stars in the galaxy — astronomers could reap a rich bounty of targets.

In many ways, these stars represent a best-case scenario for planet hunting. They are close and in clear lines-of-sight, which generally makes viewing easier. Their low mass means they are dimmer than heavier stars, so their light is less likely to mask the feeble light of a planet. And because they are young, their planets are freshly formed, and thus warmer and brighter than older planetary bodies.

Astronomers know of more than five hundred distant planets, but very few have actually been seen. Many exoplanets are detected indirectly by means of their “wobbles” — the gravitational tugs they exert on their central stars. Some are found when they transit the parent star, momentarily dimming the glare, but not dimming it enough to reveal the planet itself.

The new Galaxy Evolution Explorer technique might eventually lead to planets that can be seen directly. That would be good because, as Rodriguez points out, “seeing is believing.”

And it just might make astronomers feel a little better about the stars.

The Galaxy Evolution Explorer Web site at http://www.galex.caltech.edu describes many of the other discoveries and accomplishments of this mission. And for kids, how do astronomers know how far away a star or galaxy is? Play “How Old do I Look” on The Space Place at http://spaceplace.nasa.gov/whats-older and find out!

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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Milky Way Safari

NASA Space Placeby Dauna Coulter and Dr. Tony Phillips

  
Volunteers study infrared images of our galaxy from the Spitzer Space Telescope, identifying interesting features using the special tools of the Milky Way Project, part of the Citizen Science Alliance Zooniverse web site.
Safari, anyone? Citizen scientists are invited to join a hunt through the galaxy. As a volunteer for Zooniverse's Milky Way Project, you'll track down exotic creatures like mysterious gas bubbles, twisted green knots of dust and gas, and the notorious “red fuzzies.”

“The project began about four months ago,” says astrophysicist Robert Simpson of Oxford University. “Already, more than 18,000 people are scouting the Milky Way for these quarry.”

The volunteers have been scrutinizing infrared images of the Milky Way's inner regions gathered by NASA’s Spitzer Space Telescope. Spitzer's high resolution in infrared helps it pierce the cloaking haze of interstellar gas and dust, revealing strange and beautiful structures invisible to conventional telescopes. The Milky Way Project is helping astronomers catalogue these intriguing features, map our galaxy, and plan future research.

“Participants use drawing tools to flag the objects,” explains Simpson. “So far they've made over a million drawings and classified over 300,000 images.”

Scientists are especially interested in bubble-like objects believed to represent areas of active star formation. “Every bubble signifies hundreds to thousands of young, hot stars. Our volunteers have circled almost 300,000 bubble candidates, and counting,” he says.

Humans are better at this than computers. Computer searches turn up only the objects precisely defined in a program, missing the ones that don't fit a specified mold. A computer would, for example, overlook partial bubbles and those that are skewed into unusual shapes.

“People are more flexible. They tend to pick out patterns computers don't pick up and find things that just look interesting. They're less precise, but very complementary to computer searches, making it less likely we'll miss structures that deserve a closer look. And just the sheer numbers of eyes on the prize mean more comprehensive coverage.”

Along the way the project scientists distill the volunteers' data to eliminate repetitive finds (such as different people spotting the same bubbles) and other distortions.

The project's main site (http://www.milkywayproject.org ) includes links to a blog and a site called Milky Way Talk. Here “hunters” can post comments, chat about images they've found, tag the ones they consider especially intriguing, vote for their favorite images (see the winners at http://talk.milkywayproject.org/collections/CMWS00002u ), and more.

Zooniverse invites public participation in science missions both to garner interest in science and to help scientists achieve their goals. More than 400,000 volunteers are involved in their projects at the moment. If you want to help with the Milky Way Project, visit the site, take the tutorial, and … happy hunting!

You can get a preview some of the bubbles at Spitzer’s own web site, http://www.spitzer.caltech.edu/. Kids will enjoy looking for bubbles in space pictures while playing the Spitzer concentration game at http://spaceplace.nasa.gov/spitzer-concentration/.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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Cosmic Recount

NASA Space Placeby Dr. Tony Phillips

  
Astronomers have recently found that some galaxies have as many as 2000 small stars for every 1 massive star. They used to think all galaxies had only about 500 small stars for every 1 massive star.
Click image for larger view
News flash: The Census Bureau has found a way to save time and money. Just count the biggest people. For every NBA star like Shaquille O'Neal or Yao Ming, there are about a million ordinary citizens far below the rim. So count the Shaqs, multiply by a million, and the census is done.

Could the Bureau really get away with a scheme like that? Not likely. Yet this is just what astronomers have been doing for decades.

Astronomers are census-takers, too. They often have to estimate the number and type of stars in a distant galaxy. The problem is, when you look into the distant reaches of the cosmos, the only stars you can see are the biggest and brightest. There's no alternative. To figure out the total population, you count the supermassive Shaqs and multiply by some correction factor to estimate the number of little guys.

The correction factor astronomers use comes from a function called the “IMF” — short for “initial mass function.” The initial mass function tells us the relative number of stars of different masses. For example, for every 20-solar-mass giant born in an interstellar cloud, there ought to be about 100 ordinary sun-like stars. This kind of ratio allows astronomers to conduct a census of all stars even when they can see only the behemoths.

Now for the real news flash: The initial mass function astronomers have been using for years might be wrong.

NASA's Galaxy Evolution Explorer, an ultraviolet space telescope dedicated to the study of galaxies, has found proof that small stars are more numerous than previously believed.

“Some of the standard assumptions that we've had — that the brightest stars tell you about the whole population — don't seem to work, at least not in a constant way,” says Gerhardt R. Meurer who led the study as a research scientist at Johns Hopkins University, Baltimore, Md. (Meurer is now at the University of Western Australia.)

Meurer says that the discrepancy could be as high as a factor of four. In other words, the total mass of small stars in some galaxies could be four times greater than astronomers thought. Take that, Shaq!

The study relied on data from Galaxy Evolution Explorer to sense UV radiation from the smaller stars in distant galaxies, and data from telescopes at the Cerro Tololo Inter-American Observatory to sense the “H-alpha” (red light) signature of larger stars. Results apply mainly to galaxies where stars are newly forming, cautions Meurer.

“I think this is one of the more important results to come out of the Galaxy Evolution Explorer mission,” he says. Indeed, astronomers might never count stars the same way again.

Find out about some of the other important discoveries of the Galaxy Evolution Explorer at http://www.galex.caltech.edu/. For an easy-to-understand answer for kids to “How many solar systems are in our galaxy?” go to The Space Place at: http://tiny.cc/I2KMa

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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GOES-R, Zombie Fighter

NASA Space Placeby Dr. Tony Phillips

  
The Galaxy 15 communication satellite was “brainless” for several months in 2010 after being exposed to a geomagnetic storm. The new GOES-R satellite will warn of such dangers.
Click image for larger view
On April 5, 2010, something eerie happened to the Galaxy 15 telecommunications satellite: It turned into a zombie.

The day began as usual, with industry-owned Galaxy 15 relaying TV signals to millions of viewers in North America, when suddenly the geosynchronous satellite stopped taking commands from Earth. It was brain dead! Like any good zombie, however, its body continued to function. Within days, Galaxy 15 began to meander among other satellites in geosynchronous orbit, transmitting its own signal on top of the others’. Satellite operators scrambled to deal with the interference, all the while wondering what happened?

In horror movies, zombies are usually produced by viruses.

“In this case, the culprit was probably the sun,” says Bill Denig of the National Geophysical Data Center in Boulder, Colorado. He and colleague Janet Green of NOAA’s Space Weather Prediction Center recently led a study of the Galaxy 15 anomaly, and here are their conclusions:

On April 3rd, a relatively minor solar flare launched a cloud of plasma toward Earth. Galaxy 15 had experienced many such events before, but this time there was a difference.

“Galaxy 15 was just emerging from the shadow of Earth when the cloud arrived and triggered a geomagnetic storm,” explains Denig. Suddenly exposed to sunlight and the ongoing storm, “the spacecraft began to heat up and charge [up].”

Electrons swirling around Galaxy 15 stuck to and penetrated the spacecraft’s surface. As more and more charged particles accumulated, voltages began to rise, and —zap!— an electrostatic discharge occurred. A zombie was born.

“At least, this is what we suspect happened based on data collected by GOES satellites in the vicinity,” he says. “We’ll be able to diagnose events like this much better, however, after GOES-R is launched by NASA in 2015.”

GOES-R is NOAA’s next-generation Geostationary Operational Environmental Satellite. One of the instruments it will carry, a low-energy electron counter, is crucial to “zombie fighting.” Low energy-electrons are the ones most likely to stick to a spacecraft’s surface and cause brain-frying discharges. By monitoring these particles in Earth orbit, GOES-R will provide better post-mortems for future zombie outbreaks. This could help satellite designers figure out how to build spacecraft less susceptible to discharges. Also, GOES-R will be able to issue alerts when dangerous electrons appear. Satellite operators could then take protective action—for example, putting their birds in “safe mode”—to keep the zombie population at bay.

Meanwhile, Galaxy 15 is a zombie no more. In late December 2010, after 9 months of terrorizing nearby spacecraft, the comsat was re-booted, and began responding to commands from Earth again.

All’s well that ends well? True zombie fighters know better than to relax. Says Denig, “we’re looking forward to GOES-R.”

You and the kids in your life can learn about space weather at http://scijinks.gov/space-weather-and-us.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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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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ASTRO SAFARI TO NAMIBIA

General NewsAn Astro Safari has been organized to Namibia starting on the 30th April 2011, finishing 9th May 2011.
The trip is astronomy-biased with side trips to Namibia's wild life reserves.
The astronomy portion will be led by Mr. Andy Bender, a German astronomer (http://www.astropic.de,)
while the safaris are to be run by experienced safari guides.

The flyer, and indeed the entire trip, will be in the English language.

For further information, please click on the following link to send an e-mail:
icms-online@web.de.
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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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