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Games, Puzzles and Quizzes
14 Feb 2008 09:14:58 IST
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cool science-II(updated)
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Latest- black hole,worm hole,galaxies colliding, all lined up, space telescopes, apollo 11(great pics)
i keep updating so do come back
for those who have not seen part I,
here is the link-http://www.goiit.com/posts/list/games-puzzles-and-quizzes-cool-facts-gain-some-knowledge-41865.htm
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19 Feb 2008 15:00:29 IST
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Latest space telescopes
The Cosmic Background Explorer (COBE)
| Year launched: | 1989 |
| Telescope type: | Detector |
| Light collector: | Microwave receivers |
| Light observed: | Microwave, infrared |
Discovery Highlights:
- Found that the very young universe was not uniform ? some places had slightly more matter than others. This clumpiness provided gravitational "seeds" from which galaxies, stars, and planets grew.
The Hubble Space Telescope (HST)
| Year launched: | 1990 |
| Telescope type: | Reflector |
| Light collector: | Aluminum-coated glass mirror |
| Mirror diameter: | 94.5 inches (2.4 m) |
| Light observed: | Infrared, visible, ultraviolet |
Discovery Highlights:
- Helped determine the age of the universe and the way galaxies form. Revealed extraordinary details about the process by which Sun-like stars end their lives as planetary nebulae.
Compton Gamma Ray Observatory (CGRO)
| Year launched: | 1991 |
| Telescope type: | Detector |
| Light collector: | Gamma ray counter |
| Light observed: | Gamma ray |
Discovery Highlights:
- Established that all the mysterious sources of gamma-ray bursts lie outside the Milky Way Galaxy. Also, discovered a nearby supernova remnant.
The Chandra X-ray Observatory
| Year launched: | 1999 |
| Telescope type: | Reflector |
| Light collector: | 8 iridium-coated glass mirrors |
| Mirror diameter: | Each 32.8 inches (83.3 cm) |
| Light observed: | X-ray |
Discovery Highlights:
- Has allowed astronomers to study energetic events such as black holes, supernovae, and colliding galaxies. Has found new stars that may have planet-forming disks around them.
The Spitzer Space Telescope
| Year launched: | 2003 |
| Telescope type: | Reflector |
| Light collector: | Beryllium metal mirror |
| Mirror diameter: | 33.5 inches (85 cm) |
| Light observed: | Infrared |
Discovery Highlights:
- Has seen through dust clouds in our galaxy to better allow the study of star formation and black holes.
20 Feb 2008 07:20:23 IST
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| | |
 | What a Shock! Galaxies Caught Colliding |
A galaxy in Stephan's Quintet is rushing headlong into a cluster of neighboring galaxies at more than one million mph and generating one of the largest shock waves scientists have ever seen.
The finding, made using NASA's Spitzer Space Telescope, gives astronomers a chance to see a galactic collision in action and could help explain why some galaxies are more luminous in the infrared than others.
A cosmic pileup
Stephen's Quintet is a cluster of five galaxies located about 300 million light-years away in the constellation Pegasus. For decades, astronomers using optical telescopes have known that galaxies in the cluster had experienced encounters in the past and that some were colliding even now.
But it wasn't until they used Spitzer's Infrared Spectrograph on the galaxy cluster that they could make out the details of what was happening.
They discovered that one of the galaxies, called NGC7318b, is currently falling toward three of the others at a very high speed and generating a giant shock wave, or "bow shock," in front of it. A bow shock is akin to the ripple raised by a boat's bow as it moves through the water.
NGC7318b is estimated to be moving at more than 540 miles per second (873 kms) and generating a colossal shockwave larger than our own Milky Way Galaxy.
Faster than sound
Shock waves are generated when an object moves faster than the speed of sound through some kind of medium. On Earth, the medium is usually air or water; in space, it's interstellar gas.
One familiar type of shock wave is the "sonic boom" created by supersonic jets as they fly by overhead. As the jet moves through the air, it creates pressure waves in front and behind it. These waves travel at the speed of sound, called Mach 1. As the jet approaches this speed, it compresses the waves together into a cone-shaped "shock" which travels outward toward the ground, producing an audible boom.
In Stephan's Quintet, the shock wave generated by the infall of NGC7318b is estimated to be moving at speeds greater than Mach 100.
20 Feb 2008 07:21:21 IST
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| | |
 | Strange Setup: Andromeda's Satellite Galaxies All Lined Up |
An unusually high number of galaxies are aligned along a single plane running through the center of the giant Andromeda galaxy. Scientists don't have a theory to explain why.
Galactic cannibalism or dark matter may be responsible, researchers say.
The Andromeda galaxy is located at a distance of 2.5 million light-years away and is the nearest spiral galaxy to the Milky Way. Like our own galaxy, Andromeda is surrounded by numerous dwarf galaxy satellites. Many of these satellites are within 1.3 million light-years or less of the galaxy's main disk.
Using the Hubble Space Telescope, Eva Grebel and Andrew Koch from the University of Basel in Switzerland found that nine out of Andromeda's fourteen dwarf galaxy satellites reside in a single plane. The plane is about 52,000 light-years wide and is aligned perpendicular to Andromeda's own galactic plane, within which the galaxy's stars orbit about the center.
That nearly 80 percent of Andromeda's satellite galaxy mass is located within a single plane is highly unusual and can't be accounted for by traditional theories of galaxy formation, Grebel said.
The finding was announced recently at a meeting of the American Astronomical Society.
The Milky Way was found to contain two similar planes of satellite galaxies in the late 1980s, but with nothing to compare them to, astronomers couldn't tell if such planes were a general property of galaxy formation or whether they were just a statistical fluke.
20 Feb 2008 08:52:00 IST
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FAQ about BLACK HOLES--
What is a black hole?
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Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.
Well, first, let me assure you that the Sun has no intention of doing any such thing. Only stars that weigh considerably more than the Sun end their lives as black holes.
But I digress. What if the Sun *did* become a black hole for some reason? The main effect is that it would get very dark and very cold around here. The Earth and the other planets would not get sucked into the black hole; they would keep on orbiting in exactly the same paths they follow right now. Why? Because the horizon of this black hole would be very small -- only about 3 kilometers
What is a black hole?
---------------------
Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.
What would happen to me if I fell into a black hole?
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Let's suppose that you get into your spaceship and point it straight towards the million-solar-mass black hole in the center of our galaxy. (Actually, there's some debate about whether our galaxy contains a central black hole, but let's assume it does for the moment.) Starting from a long way away from the black hole, you just turn off your rockets and coast in. What happens?
----------------------------------------------------
Let's suppose that you get into your spaceship and point it straight towards the million-solar-mass black hole in the center of our galaxy. (Actually, there's some debate about whether our galaxy contains a central black hole, but let's assume it does for the moment.) Starting from a long way away from the black hole, you just turn off your rockets and coast in. What happens?
At first, you don't feel any gravitational forces at all. Since you're in free fall, every part of your body and your spaceship is being pulled in the same way, and so you feel weightless. (This is exactly the same thing that happens to astronauts in Earth orbit: even though both astronauts and space shuttle are being pulled by the Earth's gravity, they don't feel any gravitational force because everything is being pulled in exactly the same way.) As you get closer and closer to the center of the hole, though, you start to feel "tidal" gravitational forces. Imagine that your feet are closer to the center than your head. The gravitational pull gets stronger as you get closer to the center of the hole, so your feet feel a stronger pull than your head does. As a result you feel "stretched." (This force is called a tidal force because it is exactly like the forces that cause tides on earth.) These tidal forces get more and more intense as you get closer to the center, and eventually they will rip you apart.
My friend is sitting still at a safe distance, watching me fall into the black hole. What does he see?
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He sees things quite differently from you. As you get closer and closer to the horizon, he sees you move more and more slowly. In fact, no matter how long he waits, he will never quite see you reach the horizon.
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He sees things quite differently from you. As you get closer and closer to the horizon, he sees you move more and more slowly. In fact, no matter how long he waits, he will never quite see you reach the horizon.
Why does he see things this way? The best way to think about it is that it's really just an optical illusion.
What if the Sun became a black hole?Well, first, let me assure you that the Sun has no intention of doing any such thing. Only stars that weigh considerably more than the Sun end their lives as black holes.
But I digress. What if the Sun *did* become a black hole for some reason? The main effect is that it would get very dark and very cold around here. The Earth and the other planets would not get sucked into the black hole; they would keep on orbiting in exactly the same paths they follow right now. Why? Because the horizon of this black hole would be very small -- only about 3 kilometers
Is there any evidence that black holes exist?
---------------------------------------------
Yes. You can't see a black hole directly, of course, since light can't get past the horizon. That means that we have to rely on indirect evidence that black holes exist.
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Yes. You can't see a black hole directly, of course, since light can't get past the horizon. That means that we have to rely on indirect evidence that black holes exist.
Suppose you have found a region of space where you think there might be a black hole. How can you check whether there is one or not? The first thing you'd like to do is measure how much mass there is in that region. If you've found a large mass concentrated in a small volume, and if the mass is dark, then it's a good guess that there's a black hole there. There are two kinds of systems in which astronomers have found such compact, massive, dark objects: the centers of galaxies (including perhaps our own Milky Way Galaxy), and X-ray-emitting binary systems in our own Galaxy.
20 Feb 2008 08:54:31 IST
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Worm hole and White hole--
What is a white hole?
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The equations of general relativity have an interesting mathematical property: they are symmetric in time. That means that you can take any solution to the equations and imagine that time flows backwards rather than forwards, and you'll get another valid solution to the equations. If you apply this rule to the solution that describes black holes, you get an object known as a white hole. Since a black hole is a region of space from which nothing can escape, the time-reversed version of a black hole is a region of space into which nothing can fall. In fact, just as a black hole can only suck things in, a white hole can only spit things out.
---------------------
The equations of general relativity have an interesting mathematical property: they are symmetric in time. That means that you can take any solution to the equations and imagine that time flows backwards rather than forwards, and you'll get another valid solution to the equations. If you apply this rule to the solution that describes black holes, you get an object known as a white hole. Since a black hole is a region of space from which nothing can escape, the time-reversed version of a black hole is a region of space into which nothing can fall. In fact, just as a black hole can only suck things in, a white hole can only spit things out.
White holes are a perfectly valid mathematical solution to the equations of general relativity, but that doesn't mean that they actually exist in nature. In fact, they almost certainly do not exist, since there's no way to produce one. (Producing a white hole is just as impossible as destroying a black hole, since the two processes are time-reversals of each other.)
What is a wormhole?
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If we consider black holes that rotate and/or have charge, things get more complicated. In particular, it is possible to fall into such a black hole and not hit the singularity. In effect, the interior of a charged or rotating black hole can "join up" with a corresponding white hole in such a way that you can fall into the black hole and pop out of the white hole. This combination of black and white holes is called a wormhole.
-------------------
If we consider black holes that rotate and/or have charge, things get more complicated. In particular, it is possible to fall into such a black hole and not hit the singularity. In effect, the interior of a charged or rotating black hole can "join up" with a corresponding white hole in such a way that you can fall into the black hole and pop out of the white hole. This combination of black and white holes is called a wormhole.
The white hole may be somewhere very far away from the black hole; indeed, it may even be in a "different Universe" -- that is, a region of spacetime that, aside from the wormhole itself, is completely disconnected from our own region. A conveniently-located wormhole would therefore provide a convenient and rapid way to travel very large distances, or even to travel to another Universe. Maybe the exit to the wormhole would lie in the past, so that you could travel back in time by going through. All in all, they sound pretty cool.
But before you apply for that research grant to go search for them, there are a couple of things you should know. First of all, wormholes almost certainly do not exist. As we said above in the section on white holes, just because something is a valid mathematical solution to the equations doesn't mean that it actually exists in nature. In particular, black holes that form from the collapse of ordinary matter (which includes all of the black holes that we think exist) do not form wormholes. If you fall into one of those, you're not going to pop out anywhere. You're going to hit a singularity, and that's all there is to it.
Furthermore, even if a wormhole were formed, it is thought that it would not be stable. Even the slightest perturbation (including the perturbation caused by your attempt to travel through it) would cause it to collapse.
Finally, even if wormholes exist and are stable, they are quite unpleasant to travel through. Radiation that pours into the wormhole (from nearby stars, the cosmic microwave background, etc.) gets blueshifted to very high frequencies. As you try to pass through the wormhole, you will get fried by these X-rays and gamma rays.
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