The James Webb Space Telescope, which is scheduled to be launched by NASA in 2017 or 2018, budget permitting, and which is intended as a replacement for the Hubble Space telescope, has an interesting feature in addition to its technological advances over Hubble, it's larger mirror size (6 meters vs 3.5 meters for Hubble), and the fact that it's emphasis will be on observations in the infrared range of the light spectrum, as opposed to Hubble, which operates largely in the visual part of the spectrum. This feature isn't really a part of the telescope itself; it's the fact that it will orbit the Sun at a Lagrangian point, unlike Hubble, which orbits the earth itself at an altitude of several hundred miles.
What exactly is a Lagrangian point, you may ask. Good question. As most of us know, Sir Isaac Newton was the scientist who originally developed the theory of gravity, as an explanation why the earth and the other planets in the solar system orbited the sun in roughly circular orbits. About a century later, a Italian-French mathematician named Joseph Louis Lagrange was studying how the gravitational fields of the various bodies in the solar system interacted with each others. He found that there were certain points, which came to be called Lagrangian points (because that's how science works) where the gravitational pull of two objects in space exactly balanced each other out, which meant that an object, like an asteroid or satellite would stay at that point if it was placed there. This is what space scientists intend to do with the James Webb Space Telescope. The plan to put it at the L2 Lagrangian point, which is almost a million miles from the earth, which is a point where the gravity fields of the earth and sun exactly cancel each other out, which also means it will stay there for a very long time.
Now, you may also ask why these scientists are planning to do this when they could just put it into low earth-orbit, like Hubble. There are a number of reasons for this. For one, remember that the James Webb telescope is mainly intended for observations in the infrared range. That means that the further away it can be from sources of heat, which generate infrared rays (like the earth), the better. For another, the area in spaces where the James Webb will be is even colder than the near-earth environment where Hubble has been, which means thateven more sensitive observations can be made. It will also be further away from the zodiacal light which is near the earth, so fainter objects should be able to be seen (hopefully including planets circling other stars). And last but not least, since it will be far away from the Earth's atmosphere, scientists won't have to worry about its' orbit slowly decaying due to air resistance. So, as you can see, there are a number of advantages to placing the James Webb telescope so far from the Earth. The only real disadvantage is, if anything goes wrong, as it did with Hubble, it'll be a lot harder to send a repair mission to fix it, so maybe it's a good thing that it's not scheduled to be launched for a few more years.
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