Sometimes I complain about the earthly weather, but mostly I like to post about astronomy and space events. Hope you enjoy the articles.
By: Susie77, 12:47 AM GMT on August 22, 2009
We're off to Alaska tomorrow! See you in two weeks. Take care, stay dry, and enjoy the skies!
By: Susie77, 8:30 PM GMT on August 16, 2009
Space Weather News for Aug. 16, 2009
MONDAY MORNING SKY SHOW: Set your alarm for dawn. On Monday morning, Aug. 17th, Venus and the crescent Moon will gather beautifully close together in the eastern sky. For many observers in North America, the International Space Station (ISS) will make an appearance, too. It's a fantastic way to begin the day. Check http://spaceweather.com for a sky map and ISS flyby predictions.
By: Susie77, 9:06 PM GMT on August 12, 2009
Space Weather News for August 12, 2009
If it's dark where you live, go outside and look for meteors. Earth is still inside the debris stream of Comet Swift-Tuttle and, as a result, the Perseid meteor shower is still active. Worldwide meteor counts raise the possibility that the show could be better tonight, Aug. 12th, than it was last night, Aug. 11th. Be alert for meteors after sunset.
Photos and updates are available at http://spaceweather.com .
By: Susie77, 11:51 AM GMT on August 11, 2009
Space Weather News for August 11, 2009
The Perseid meteor shower is about to peak. The show begins after sunset on Tuesday, August 11th, and continues until the sun rises on Wednesday, August 12th. A time of particular interest is 0800-0900 GMT (1-2 a.m. PDT) on the 12th. That's when Earth is expected to pass through a denser-than-usual filament of dust from Perseid parent Comet Swift-Tuttle. Forecasters are unsure what will happen, but some have speculated that meteor rates could surge as high as 200 per hour. Bright moonlight will blot out many of those Perseids, but even a fraction of 200 is a good show.
By: Susie77, 11:52 PM GMT on August 10, 2009
Horse Flies and Meteors
August 10, 2009: Splat! There goes another bug on the windshield.
Anyone who's ever driven down a country lane has seen it happen. A fast moving car, a cloud of multiplying insects, and a big disgusting mess.
The next time that happens to you, instead of grossing out, try thinking of the experience as an astronomy lesson. Your car is Earth. The bugs are tiny flakes of comet dust. The carnage on your windshield ... it's a meteor shower!
Earth, like a speeding car, races around the Sun sweeping up everything in its path. There are no insects in space, at least none that we know of, but there are plenty of meteoroids, little flakes of dust from comets and asteroids. They hit Earth's atmosphere and--splat!--they disintegrate as fiery streaks of light called meteors.
This week lots of meteors will appear over Earth's northern hemisphere when our planet plows through a swarm of dust shed by periodic comet Swift-Tuttle. It's the annual Perseid meteor shower, which peaks on August 11th and 12th.
Earth has a windshield? It's the atmosphere, which protects us from solar wind and comet dust much as a car's windshield protects passengers from wind, rain and bugs. Earth's front windshield is the early morning sky. Earth circles the Sun dawn-side first, scooping up whatever lies on that side of the planet. That's why it's usually best to look for Perseids just before dawn.
A good time to see Perseids this year is before dawn on Wednesday morning, August 12th, when Earth's front windshield is overhead. You could see dozens of meteors despite the glare of a 66% gibbous Moon.
Side windows, the ones to the left and right of passengers in cars, are good, too. Zooming down a bug-infested lane, side windows don't intercept many insects, but the ones they do gather are worth examining. Bugs that strike side windows do so at a shallow angle, leaving long and colorful streaks.
This also happens to meteors. When the constellation Perseus (the source of the Perseids) hangs low near the horizon, meteors streaming from Perseus will skim the the top of Earth's atmosphere, much like a bug skimming the side window of an automobile. Astronomers call these meteors "Earthgrazers." They tend to be long and colorful.
Look for Perseid Earthgrazers on Tuesday night, Aug. 11th, between about 9:00 and 11:00 pm local time.
Earthgrazers don't come in large numbers. The special geometry required to produce them keeps counts low, but even one or two is enough. A breathtaking Earthgrazer is the sort of meteor you're likely to remember for years.
Best of all, there's no gooey residue.
By: Susie77, 11:17 PM GMT on August 06, 2009
( Well, I made that last bit up...LOL )
Kepler Detects an Exoplanet Atmosphere
August 6, 2009: NASA's new exoplanet-hunting Kepler space telescope has detected the atmosphere of a known giant gas planet, demonstrating the telescope's extraordinary scientific capabilities. The discovery will be published Friday in the journal Science.
"As NASA's first exoplanets mission, Kepler has made a dramatic entrance on the planet-hunting scene," said Jon Morse, director of the Science Mission Directorate's Astrophysics Division at NASA Headquarters in Washington. "Detecting this planet's atmosphere in just the first 10 days of data is only a taste of things to come. The planet hunt is on!"
Launched March 6, 2009, from Cape Canaveral Air Force Station in Florida, Kepler will spend the next three-and-a-half years searching for planets as small as Earth, including those that orbit stars in a warm "Goldilocks zone" where there could be water. It will do this by looking for periodic dips in the brightness of stars, which occur when orbiting planets transit, or cross in front of, the stars.
"When the light curves from tens of thousands of stars were shown to the Kepler science team, everyone was awed; no one had ever seen such exquisitely detailed measurements of the light variations of so many different types of stars," said William Borucki, the principal science investigator and lead author of the paper.
The observations were collected from a planet called HAT-P-7, known to transit a star located about 1,000 light years from Earth. The planet orbits the star in just 2.2 days and is 26 times closer than Earth is to the sun. Its orbit, combined with a mass somewhat larger than the planet Jupiter, classifies this planet as a "hot Jupiter." It is so close to its star, the planet is as hot as the glowing red heating element on a kitchen stove.
HAT-P-7 was known before Kepler turned its attention to the planet. Kepler's measurements are so precise, however, they show something new: a smooth rise and fall of the light between transits caused by the changing phases of the planet, similar to the phases of our own Moon. The smooth rise and fall of light is also punctuated by a small drop in light, called an occultation. An occultation happens when a planet passes behind its star.
The new Kepler data can be used to study this hot Jupiter in unprecedented detail. The depth of the occultation and the shape and amplitude of the light curve show the planet has an atmosphere with a day-side temperature of about 4,310 degrees Fahrenheit. Little of this heat is carried to the cool night side. The occultation time compared to the main transit time shows the planet has a circular orbit. The discovery of light from this planet confirms the predictions by researchers and theoretical models that the emission would be detectable by Kepler.
The observed brightness variation is just one and a half times what is expected for a transit caused by an Earth-sized planet. Although this is already the highest precision ever obtained for an observation of this star, Kepler will be even more precise after analysis software being developed for the mission is completed.
"This early result shows the Kepler detection system is performing right on the mark," said David Koch, deputy principal investigator of NASA's Ames Research Center at Moffett Field, Calif. "It bodes well for Kepler's prospects to be able to detect Earth-size planets."
Stay tuned to Science@NASA for more results from Kepler.
By: Susie77, 12:09 AM GMT on August 05, 2009
POSSIBLE PERSEID METEOR OUTBURST: This year's Perseid meteor shower could be even better than usual. According to NASA's Meteoroid Environment Office, a filament of comet dust has drifted across Earth's path and when Earth passes through it, sometime between 0800 and 0900 UT (1 - 2 am PDT) on August 12th, the Perseid meteor rate could surge to twice its normal value. Check http://spaceweather.com for details and observing tips.
By: Susie77, 11:37 AM GMT on August 03, 2009
August 3, 2009: It began with a furrowed brow, a moment of puzzlement, quickly dismissed.
The date was July 19, 2009. Amateur astronomer Anthony Wesley was photographing Jupiter from his backyard observatory in Murrumbateman, Australia, when something odd caught his eye.
"My attention was fixed on the Great Red Spot, which was setting beautifully over Jupiter's horizon," recalls Wesley. "I almost didn't notice the dark blemish near Jupiter's south pole, and when I did, I put it out of my mind."
It's just another dark storm on Jupiter.
"That's what I thought at first, but something about the dark mark puzzled me, it didn't look right, and I couldn't stop stealing glances at it."
Slowly, Jupiter's rotation turned the blemish toward Earth, Wesley got a better look at it, and the truth struck him like a thunderbolt.
It was an impact mark. Something hit the giant planet!
"I had seen the scars caused by fragments of Comet Shoemaker-Levy 9 hitting Jupiter in 1994, so I knew what an impact looked like," he says. "After I'd convinced myself that this was real, I could hardly use the computer. My hands were shaking. It was quite unbelievable."
He quickly emailed his photos to friends and colleagues around the world, and within hours telescopes great and small were turning toward Jupiter to photograph the aftermath of a powerful collision.
"We believe it was a comet or asteroid measuring perhaps a few hundred meters wide," says Don Yeomans of NASA's Near-Earth Object Office at JPL. "If something of similar size hit Earth—we're talking about 2000 megatons of energy--there would be serious regional devastation or a tsunami if it hit the ocean."
In a stroke of luck almost as big as Wesley's, JPL astronomers Glenn Orton and Leigh Fletcher were already scheduled to observe Jupiter on July 20th, barely a day after impact, using NASA's Infra-red Telescope Facility (IRTF) atop Mauna Kea in Hawaii. The 3-meter telescope revealed a fresh cloud of debris about the size of Mars floating among Jupiter's clouds.
"The object, whatever it was, exploded in Jupiter's upper atmosphere," says Orton. "It blew itself to smithereens. What we're seeing now are bits and pieces of the impactor and possibly some strange aerosols formed by shock-chemistry during the impact."
On July 23rd, the Hubble Space Telescope took its first pictures of the blast site. Hubble was still undergoing checkout and calibration following the STS-125 servicing mission in May, but this event was too big to skip. Space Telescope Science Institute director Matt Mountain allocated emergency telescope time to a team of astronomers led by Heidi Hammel of the Space Science Institute in Boulder, Colorado.
As usual, Hubble photos stole the show. They revealed a swirling maelstrom of dark cindery debris jostling with natural storms near the top of Jupiter's atmosphere:
"The debris cloud is lumpy because of atmospheric turbulence," explains planetary scientist Amy Simon-Miller of the Goddard Space Flight Center. "Polar winds blowing 25 m/s (~55 mph) are causing it to spread out and grow larger. This will make the cloud even easier to see through backyard telescopes."
Judging from the behavior of the Comet Shoemaker-Levy 9 impacts fifteen years ago, she estimates that the 'Wesley debris cloud' could remain visible for many weeks to come. Researchers will put the time to good use. Further studies of the cloud might yet reveal the great unknown:
What hit Jupiter?
"We just don't know," says Yeomans. "No one saw the object prior to impact."
Indeed, there was no warning. The object emerged from darkness, unknown and uncatalogued, and—wham!—before anyone could photograph the body intact, it had become a cloud of debris. (There is a lesson here for Earth, but that is another story.)
The cloud's chemical composition holds clues to the nature of the impactor. Orton says ground-based observers are now analyzing light reflected from the cloud to figure out what it is made of. "If the spectra contain signs of water, that would suggest an icy comet. Otherwise, it's probably a rocky or metallic asteroid."
Meanwhile, it's a big dark mystery—the kind that Wesley can't take his eyes off of. "I am still observing Jupiter almost every night using my 14.5 inch telescope," he says. "The cloud is expanding and taking on some interesting shapes."
"I wonder," he says, "what will happen next?"