Draconid Meteors 8 oct. 2011

For the next few nights, Draco the Dragon will be spitting out “shooting stars,” also known as meteors. The Draconid shower is predicted to produce the greatest number of meteors on the night of October 8, 2011. Watch for them starting at nightfall. Unfortunately, the waxing gibbous moon will wipe many of these meteors from view, and oftentimes the hard-to-predict shower doesn’t offer much more than a handful of languid meteors per hour.

However, this shower produced major displays in 1933 and 1946 – with thousands of meteors per hour seen in those years – but since then has been so spotty that the tried-and-true Observer’s Handbook – source of so much wonderful sky info – lists a “?” for the rate of meteors expected at the peak of the Draconids. This year, however, some astronomers are calling for a Draconid meteor shower to burst into storm in 2011, with rates of 1,000 meteors per hour.

The forecast calls for the peak to occur between 17:00 and 18:00 Universal Time on October 8, 2001. If the prediction holds true, that means Europe, northern Africa and the Middle East will get to watch the Draconids at their peak. But keep in mind that meteor showers are notorious for defying predictions, either surpassing or falling shy of expectation, so you never know for sure. Even if the storm materializes, the bright moon will undoubtedy wash away many of these meteors. 

If you live at middle and far northern latitudes, though, it’s well worth a try. Unlike many major showers, the radiant for the Draconids is highest up at nightfall, so watch for these meteors as soon as darkness falls. 

Most meteor showers are named for the constellation from which the meteors radiate on the sky dome. The Draconids, however, are sometimes also called the Giacobinids, to honor the man who first sighted the comet that spawned this meteor shower. 

Michel Giacobini discovered this comet on December 20, 1900. Another sighting in 1913 added Zinner to the name of the comet, 21P Giacobini-Zinner. It is a periodic comet, which returns every 6 years and 4 months. Tracking this comet, and noting this October meteor shower, helped astronomers figure out how to predict meteor showers in 1915. The great Draconid/Giacobinid meteor storms occurred in 1933 and 1946. The comet returned in 1998 as well, and the Draconids picked up that year, but only to a rate of about 100 per hour.

Coming up in our lifetimes, in the year 2013 – approximately two years after the comet approaches perihelion (closest approach to the sun) – there might be another meteor storm around the time of this shower’s peak. Or there might not be.

There might be a meteor storm this year, in 2011. Perhaps the rates could go up to hundreds of meteors per hour in North America. Or we might see only a handful of meteors per hour. Under normal conditions, when astronomers speak of a meteor shower peaking, it is similar to a weather forecaster saying, “The heaviest rain/snow is predicted for such-and-such hour.” In other words, the prediction might not be precise, since nature is always unpredictable to a degree. But the rate of the meteors is higher during the peak of a meteor shower than on any other night.

For a taste of history related to this shower, go to the Astronomy Abstract Service from the Smithsonian and NASA and find a 1934 article called “The Meteors from Giacobini’s Comet” by C.C. Wylie. It is an account of the famed meteor storm of 1933.

If you want to try your luck, lie down on a reclining chair with your feet pointing northward. Find as much open sky as possible. How many Draconid meteors will be seen in the moonlit skies these next few evenings?

 by "environment clean generations"

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Posted in: comet,draconid meteors,draconides,europe,meteor shower,shooting stars,space

Why Do Leaves Change Color? No, Seriously!

The secrets of why the leaves of trees change yellow or red in the autumn are slowly being revealed. Those eye-seducing hues, it appears, are a lot more than pretty. They're the result of trees doing their utmost to survive. They're the shades of evolutionary success. 

Let's start with the green leaf: We all learned in school that it's the result of the most abundant pigment in the leaf being the green chlorophyll. When the cool air and shorter days of autumn arrive, leaves change to red or yellow not because the leaves are dying, but because of a series of clever processes underway.

Not so surprisingly, yellow leaves undergo one sort of color changing process and red leaves another. As the chlorophyll is being turned off, most leaves turn yellow, which is just a color that's already in the leaves but is usually flooded by green the rest of the growing season. 

But over the last decade or so, researchers have discovered something very different goes on in red leaves. As their chlorophyll drops, they would also turn yellow if not for the sudden rapid production of a brand new red pigment call anthocyanin, which was not previously present in the leaves.

This surprising revelation has led to a surge of interest by scientists who are trying to explain why a leaf with only a week or so to live would bother producing an entirely new pigment.

One theory for explaining red leaves is that they are the result of 35 million years of trees battling insects looking for places to get a last meal and lay their eggs in the fall. Red leaves are harder for insects like aphids to see, for instance, so they tend to go for the yellow leaves.

Some evidence for this theory can be found in the differences of fall colors between North America and Europe. There are few native European trees that turn red in fall, but they are mostly yellow. In North America, however, there are ample red-turning trees, as well as yellow. 

The reason for this may be that in North America, as well as in East Asia, North-South running mountain ranges allowed forests to shift their ranges North and South with climate changes, carrying their insects -- and their long-standing battles -- along the way.

In Europe, however, the major mountain ranges run east-west. So as climate warms or cools, trees have nowhere to go and simply die out -- along with the insects that live off of them. So in Europe, the insect-tree battles have a much shorter history, and so less time to evolve strategies like anthocyanins to fend them off. 

This theory was put forward by Simcha Lev-Yadun of the Department of Science Education- Biology at the University of Haifa-Oranim and Jarmo Holopainen of the University of Kuopio in Finland, and published in the journal New Phytologist.

Another theory suggests that the variation of red anthocyanin in leaves of trees that live in the same area might have more to do with the richness or poverty of the soil in which a tree grows and so it reflects the lengths trees must go to hang onto the nutrients they have invested in their leaves.

In a preliminary study by a student in Charlotte, N.C., it was found that fall leaf colors and the soils under sweet gum and red maple trees show a significant nutrient difference that matches autumn tree color patterns. The richer lowland soils corresponded to more yellow leaves and poorer highland soils correlated to redder leaves.

"It's very clear that there's a correlation," said plant physiologist Bill Hoch of Montana State University in Bozeman. What's more, it matches what he has discovered about the function of that stunning red anthocyanin.

Experiments make a pretty strong case for anthocyanin serving as a protective pigment that helps trees in nutrient-poor or stressed places to maximize the nutrients they can draw from the leaves before they are dropped to the ground, Hoch told Discovery News in an October 2007 article.

"They pull as many of the nutrients back into the plants as possible," said Hoch.

The red pigment protects any remaining green, food-making chloroplasts in the leaves from damage. This is especially valuable for trees in nutrient-poor soils or stressful situations because this "photo-protection" allows the leaves to keep making sugars in their leaves longer.

This, in turn, is vital for pulling nutrients out of the leaves because the only way the nutrients can be extracted from leaf to trunk is by hitching a ride on the trunk-bound sugars.

The bottom line, Hoch explained, is that the longer photosynthesis can continue on an autumnal, coloring leaf, the more nutrients can be drawn out of it for re-use in the spring. So where every drop of nutrient counts the most -- like perhaps on some nutrient-poor hillsides of North Carolina -- red is the color of autumn.

by "environment clean generations"

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Posted in: autumn,earth,europe,leaves,mountain,nutrient,photosynthesis,Seriously,Why Do Leaves Change Color No,yellow

Europe And Russia Sending Man To Mars?

It's usually the assumption that the first man or woman to first set foot on Martian dirt will be American. After all, the only men to walk on the lunar surface were employed by NASA.

This assumption could be turned on its head if a recent announcement by the head of the European Space Agency (ESA) follows through.

Speaking to reporters at an air show near Moscow on Wednesday, Jean-Jacques Dordain said ESA and Roskosmos (the Russian space agency) would "carry out the first flight to Mars together," according to RIA Novosti.

Naturally, there's no promise of a target date, but Dordain's announcement underscores an important fact: to get humanity to Mars, international collaboration will be desirable. Perhaps even essential.

Interestingly, one of the key deciding factors for the joint ESA/Roscosmos proposition appears to be the Russian Mars500 project. Mars500 is a 520-day simulated "mission" to the Red Planet being run by Russia's Institute of Biomedical Problems. ESA is also involved in the project.

 In November, the crew of Mars500 are set to be released from confinement when they "return to Earth." The crew of six men (controversially, no women were selected to participate) are currently enduring the confines of a 550-cubic-meter (19,400-cubic-foot) mock spaceship, studying the physiological and psychological impact of an 18 month return trip to Mars.

  Ahuge amount of energy is being directed into planning for mankind's "next great step," but politics and money all-too-often gets in the way of any real progress being made.

Perhaps ESA and Roscosmos can sidestep the worst financial issues by combining resources and setting their international sights on Mars. After all, landing a human on an alien world should be an international effort, but whether or not this happens remains to be seen.

 by "environment clean generations"

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Posted in: europe,mars,nasa,russia