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|Aug. 1 Solar Eclipse||
Friday, August 1 is a red-letter day for eclipse enthusiasts. On that date, the sun will be partially eclipsed over an immense area that includes western and central Asia, parts of northern and central Europe, all of Greenland and even a small slice of northeastern North America.
A total solar eclipse — the first in nearly two and a half years — will be visible along a narrow track that will start over the Northwest Passage of Canada, gives a glancing blow to northern Greenland, then shifts southeast through Siberia and western Mongolia and before ending near the famed Silk Route of China.
The path of totality for this upcoming eclipse is never more than 157 miles (252 km) wide.
Where it’s visible
The western United States is in for a skywatching treat tonight: a total lunar eclipse. The eastern half of the country will see part of the eclipse before the Moon sets around sunrise.
A lunar eclipse takes place when the full Moon — which lines up directly opposite the Sun — moves through Earth’s shadow. The Moon’s orbit around Earth is tilted a little, so most of the time, the Moon passes above or below the shadow. An eclipse occurs only when the geometry is just right — as it is tonight.
The eclipse begins at 2:54 a.m. Central Daylight Time, when the lunar disk first touches the outer portion of the shadow, called the penumbra. The penumbra is so faint, though, that most people won’t even notice it.
You will notice when the Moon moves into the central part of the shadow, called the umbra. It takes a dark “bite” out of the Moon — a bite that grows larger as the Moon moves deeper into the shadow. The Moon will first touch the umbra at 3:51 a.m. It’ll be fully immersed in the umbra an hour later, and remain in full eclipse for an hour and a half.
From the East Coast, the Moon will still be fully eclipsed as it sets. From points farther west, though, you’ll be able to see the Moon begin to emerge from the shadow, as more of the lunar disk returns to sunlight. It’ll fully emerge from the umbra at 7:24 a.m., so the Moon will still be in view from the western Great Plains to the Pacific Coast.
|Distant Planets Could Have Plants of Alien Colors||
Scientists may be able to determine the color of extraterrestrial plant life while studying distant planets, according to a pair of new studies.Researchers have developed a way to analyze the light emitted by a given planet’s parent star and determine how that light interacts with various chemicals in the planet’s atmosphere.
This gives scientists an idea of the wavelengths, or colors, of light that reach the planet’s surface.
On Earth, red light is most abundant, while blue light is most energetic, or useful to plants. So plants tend to absorb these colors and reflect the less useful green light, said Nancy Kiang, a biologist at NASA’s Goddard Institute for Space Studies in New York.
But other stars may emit different wavelengths of light, and their planets may have different chemicals in their atmospheres, she explained. So the dominant colors reaching the surfaces of other planets may be unlike those on Earth.
This means that distant worlds could theoretically feature plants that are red, yellow, or blue.
“We’re actually predicting what pigments absorb … but you can conjecture what range of colors they might wind up reflecting since they’re not absorbing them,” Kiang said.
Search for Alien Plant Life
Kiang and colleagues used computer models to develop their method of studying light on distant worlds. Two related papers on the process appear in the March issue of the journal Astrobiology.
The models simulate different kinds of light emitted by stars that are hotter and cooler than the sun. The models then weigh how that light would interact with a planet’s chemistry, what light would reach the ground, how plants would use that light, and other variables.
Co-author Victoria Meadows is an astrobiologist at the California Institute of Technology in Pasadena. She said the research will also help scientists detect life on extrasolar planets.
Photosynthesis—the process plants use to turn light into sugar—produces detectable signs of life at a global scale, she explained.
Photosynthesis on Earth is responsible for atmospheric oxygen and ozone. The same may be true on other planets, she said.
“That oxygen and ozone on Earth can be seen from space. It can be seen from a very great distance, so it’s a good thing to go after [when searching for extraterrestrial life],” she said.
“It’s not only the fact that we think photosynthesis is highly likely if there’s surface life, but also the signs of photosynthesis are relatively easy to detect,” Meadows said.
The new research, the authors added, will guide the development of future telescopes designed to search for life on other planets.
NASA’s Kepler spacecraft, scheduled to launch in October 2008, will be able to detect Earth-size planets in habitable zones around distant stars. This will help scientists understand whether these types of planets are common.
Scientists hope future space telescopes, such as NASA’s proposed Terrestrial Planet Finder and the European Space Agency’s Darwin, will be able to find and study nearby extrasolar planets.
The telescopes will allow scientists to determine what a given planet’s surface is made of and what chemicals are in its atmosphere.
That information, combined with data on the wavelengths of light from the parent star, will allow scientists to determine what colors of light the planet’s plants most likely use for photosynthesis—and what colors they reflect.
“That’s what this research is relevant to,” Meadows said.
for National Geographic News
“It’s going to be a great show,” says Bill Cooke of NASA’s Meteoroid Environment Office at the Marshall Space Flight Center. “The Moon is new on August 12th–which means no moonlight, dark skies and plenty of meteors.” How many? Cooke estimates one or two Perseids per minute at the shower’s peak.
A Perseid fireball photographed August 12, 2006, by Pierre Martin of Arnprior, Ontario, Canada. [Larger image]
|Colossal Four-Galaxy Collision Discovered||
Four galaxies are crashing into each other in one of the largest collisions ever seen, scientists say.
The galactic crash was spotted by astronomers using NASA’s Spitzer Space Telescope, which detected a fan-shaped plume coming from a cluster of galaxies nearly five billion light-years away.
When fully merged, the new galaxy will be up to ten times as large as the Milky Way, astronomers said.
“Most galaxy mergers are like small pickup trucks filled with sand colliding,” explained Kenneth Rines, an astronomer at the Harvard-Smithsonian Center for Astrophysics.
“This big merger is like two big rigs full of sand colliding and flinging sand everywhere. In this case, the sand represents stars.”
Common Occurrence Made Unique
Galactic mergers are fairly common, Rines explained. (Read related story: “Earth Likely to Relocate in Galactic Collision” [May 16, 2007].)
Most cosmic crashes involve two galaxies of similar size or smaller galaxies coalescing into a larger one.
What makes this event unique is the sheer size and number of galaxies involved, Rines said.
“This is a very unusual case,” Rines said. “It’s a first to have four galaxies merging.”
Three of the star systems are about the size of the Milky Way, and the fourth is about three times as large.
(Download a wallpaper photo of the Milky Way.)
Another unique aspect of the merger is the apparent lack of new stars being formed, Rines added.
Typically when galaxies converge, the intervening gas clouds compress and begin to form stars, he explained. But scientists have not detected gas clouds in the four galaxies, which means no new stars will be born from the merger.
Rines’ team will publish the discovery in an upcoming issue of Astrophysical Journal Letters.
Benefit of Happenstance
Rines said the megacollision will help scientists learn more about how large galaxies are formed.
“This merger tells us that you can make a clear distinction between when a star in a galaxy forms and when the galaxy itself assembles,” he said.
In this case, all of the stars had formed before the merger.
“But if you had just looked at the star age [once the new galaxy is fully formed], you would have assumed the galaxy is much older than it really is,” he noted.
Rines hopes to see more of these megamergers, but he admits it was happenstance that his team spotted the new one during a survey of distant galaxy clusters.
He’s also not holding out hope that he’ll see the monster galaxy fully formed in his lifetime—it will take about a hundred million years for these four galaxies to finally become one.
Sara Bennington McPherson
for National Geographic News
The Lyrid meteor shower has been observed for more than 2,000 years; Chinese records say “stars fell like rain” in the shower of 687 B.C. But in recent times the Lyrids have generally been weak. They have a brief maximum that lasts for less than a day, and even then only 10 to 20 Lyrids per hour may appear.
But there have been some remarkable exceptions. In 1982 the rate unexpectedly reached 90 for a single hour, and 180 to 300 for a few minutes. A brief outburst of 100 per hour was also seen in 1922. And on April 20, 1803, the residents of Richmond, Virginia, upon being rousted out of bed by a fire bell, were startled to see great numbers of meteors in all parts of the sky. “This unpredictability always makes the Lyrids a shower to watch, since we cannot say when the next unusual return may occur,” note Alistair McBeath and Rainer Arlt of the International Meteor Organization.
This year’s prime viewing time is the predawn hours of Monday, April 22nd. Once the waxing gibbous Moon sets around 4 a.m. daylight saving time, the sky should be fairly dark for an hour or so until morning twilight seriously interferes. The radiant point of this shower lies between the bright summer star Vega and the keystone pattern of the constellation Hercules.
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We’re in a full moon. I don’t like full moons. Ah, the moon which alters life, gives ppl the excuse to act a lil crazier and causes tides to shift. There is mystery there. Kinda like what’s going on now. Things voluntarily shifting with a mysterious edge to it. Situations are moving towards the better as they always do – “trouble don’t last always.” I’ve found that it’s my imagination that helps me through these times. I often find myself imagining the days away. My mind drifts all the time now. During conversations, I can’t seem to pay attention..I’m too busy concentrating on different existences..situational thinking… In my own lil world where things happen as I wish. I’ve been there more than 10 yrs now and probably will continue to be there for the rest of my so-called life. My imagination keeps me alive.