Friday, October 21, 2011

The sky is falling...again, 10.21.11

Not only is another meteor shower coming this way, but yet another gargantuan satellite is making its way back to Earth this weekend.

The Orionids meteor shower began about three or four days ago, and will continue to build until its climax on the morning of October 22nd, just before sunrise. Called the “Orionids” because the meteors seem to be falling out of the constellation Orion the hunter, the bright streaks and fireballs are actually created by detritus from Halley’s comet, burning up in our atmosphere.

Like a trail of fairy dust behind the Pigpen of fairies, the comet leaves a long, filthy (but sparkly—it is mostly ice) trail behind it. When Earth passes through the trail of dirt, dust, and ice, the resulting friction created by the pieces scrubbing against our atmosphere causes them to burn up.

Do not expect the meteor shower to blow you away, though. The Orionids is only expected to produce about 20-25 meteors per hour. In the past, the Orionids have also been very dim, so do not expect to see any if you are in an urban area with lights on at night. The best place to observe a meteor shower (or anything in astronomy, really), is to find a safe, dark, wide-open field in a rural area. The less light from nearby cities and towns you see on the horizon, the better. The Orionids are perfect for a nice calm, quiet evening of sky watching.

You may also want to keep an eye out for ROSAT, the 2.7-ton German X-ray satellite. Remember UARS, which fell to its death in the Pacific Ocean late last month? Well, it seems another one of the mechanical behemoths has bit the dust and is in the process of winding its way down to Earth.

Unlike UARS, which mostly broke up or burned up in our atmosphere, ROSAT is expected to have over 1 ton of its pieces survive reentry into Earth’s atmosphere. While the chances for getting hit by it are higher than they were for UARS, they are still only about 1 in 2000. It may look great if you happen to catch a glimpse of it through a nice pair of binoculars, but the odds are far against it doing any real damage.

While it is impossible at this point to predict exactly when or where ROSAT will make its final resting place, scientists do guesstimate this it should make landfall over the weekend, either Saturday afternoon or Sunday morning. The best predictions they can manage are about 5 or 6 hours before it hits the ground.


Finding the dark with light, 10.21.11

NASA scientists are using the Hubble Space Telescope to detect dark matter using light. This may sound odd, but the researchers found out it is possible.
Image credit: NASA, ESA, M. Postman (STScl), and the CLASH Team.
The principle that allows it to work is something called gravitational lensing, an effect predicted by Einstein in the early part of the 20th century. The idea is that when a large object with considerable mass passes in front of a light source, it causes the light to focus temporarily as it is literally pulled a little bit towards the object, thus making the light appear a little brighter for a time.
On the galactic scale, we do not see it quite so much as a flare, but rather we see bends or curves in the light. In this image here, you can clearly see some areas of light that are distorted, seeming to bend around nothing. That “nothing,” the researchers have determined, is dark matter, the as of yet enigmatic stuff that is proving very difficult to study. The vast majority of things that researchers have learned about dark matter can only be gleaned from its seeming effect on everything else. It is something they cannot see and cannot reach yet due to the current limitations of our space travel programs. Hopefully with enough studies they can determine what it is. As dark matter makes up the bulk of the universe’s mass, scientists are very eager to figure it out.
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Monday, October 3, 2011

Life-friendly zones in the galaxy? 09.30.11

With all the changes happening in the sciences lately, it is no small wonder that astronomers are beginning to re-think the “big picture” in their theories. For centuries, humans have wondered about the possibility of life elsewhere in the universe, and since the advancement of space technology, the hunt has become ever more insistent. Yet, with each little hint of the possibility of life, one or more factors always seem to be missing. Some astronomers are now beginning to reformulate their search plans and not look just for other solar systems elsewhere, but try to determine if there are specific areas throughout our galaxy that are more life-friendly.
In every solar system, depending on the class of the central star(s), there is a certain distance away from the center that is the most temperate area for supporting life as we know it. This zone is usually referred to by astronomers as the life zone, “habitable zone,” or even the “Goldilocks zone,” because it is not too hot or too cold. For instance, in our solar system, Mercury and Venus are much closer to our own sun, and as such experience much higher average temperatures year-round. Jupiter, Saturn, Uranus, and Neptune are all much, much further away from the sun than Earth, and are all much colder. Astronomers are still very hopeful about the possibility of life on Mars.
Image credit: NASA/JPL-Caltech/ESA/CXC/STScI.
So, if there is a specific life zone in every solar system, does the same rule apply for galaxies? Some astronomers are beginning to believe so, arguing that the centers of galaxies tend to be much more metal-heavy, which is much more conducive to planetary formation, so the odds are in favor of a planet forming with life on it. The flipside of the argument, however, is that the centers of galaxies also tend to be home to more supernovae. While all the constant light would be annoying, any life on planets in the galactic center would have to worry about much more serious problems like ozone depletion and literally having the planet fried by all manner of ray emissions from the multitude of stars. For now, the researchers will continue to scan the center of our own galaxy (pictured here) for more evidence and see how their theories unfold.