Flash is dying a death by 1,000 cuts, and that's a good thing
These points are named after Joseph-Louis Lagrange, an 18th-century mathematician who wrote about them in a 1772 paper concerning what he called the "three-body problem." They are also called Lagrangian points and libration points.
There are five Lagrange points around major bodies such as a planet or a star. Three of them lie along the line connecting the two large bodies. In the Earth-sun system, for example, the first point, L1, lies between Earth and the sun at about 1 million miles from Earth. L1 gets an uninterrupted view of the sun, and is currently occupied by the Solar and Heliospheric Observatory (SOHO) and the Deep Space Climate Observatory.
L2 also lies a million miles from Earth, but in the opposite direction of the sun. At this point, with the Earth, moon and sun behind it, a spacecraft can get a clear view of deep space. NASA's Wilkinson Microwave Anisotropy Probe (WMAP) is currently at this spot measuring the cosmic background radiation left over from the Big Bang. The James Webb Space Telescope will move into this region in 2018.
The third Lagrange point, L3, lies behind the sun, opposite Earth's orbit. For now, science has not found a use for this spot, although science fiction has.
“NASA is unlikely to find any use for the L3 point since it remains hidden behind the sun at all times,” NASA wrote on a web page about Lagrange points. “The idea of a hidden 'Planet-X' at the L3 point has been a popular topic in science fiction writing. The instability of Planet X's orbit (on a time scale of 150 years) didn't stop Hollywood from turning out classics like 'The Man from Planet X.'”
L1, L2 and L3 are all unstable points with precarious equilibrium. If a spacecraft at L3 drifted toward or away from Earth, it would fall irreversibly toward the sun or Earth, "like a barely balanced cart atop a steep hill," according to astronomer Neil DeGrasse Tyson. Spacecraft must make slight adjustments to maintain their orbits.
Points L4 and L5, however, are stable, "like a ball in a large bowl," according to the European Space Agency. These points lie along Earth's orbit at 60 degrees ahead of and behind Earth, forming the apex of two equilateral triangles that have the large masses (Earth and the sun, for example) as their vertices.
Because of the stability of these points, dust and asteroids tend to accumulate in these regions. Asteroids that surround the L4 and L5 points are called Trojans in honor of the asteroids Agamemnon, Achilles and Hector (all characters in the story of the siege of Troy) that are between Jupiter and the Sun. NASA states that there have been thousands of these types of asteroids found in our solar system, including Earth’s only known Trojan asteroid, 2010 TK7.
L4 and L5 are also possible points for a space colony due to their relative proximity to Earth, at least according to the writings of Gerard O'Neill and related thinkers. In the 1970s and 1980s, a group called the L5 Society promoted this idea among its members. In the late 1980s, it merged into a group that is now known as the National Space Society, an advocacy organization that promotes the idea of forming civilizations beyond Earth. ..."
- JasonSpeakingPrinciple, 1994 - present
- Capital OneSr. Creative Director, 2014 - present
Jason combines creative and technical know-how to help people communicate online. He has worked with businesses and organizations including Marriott International, AOL, Virgin, Bank of America, The Aspen Institute, The Solar Energy Industry Association, and The USDA. Jason is a long standing leader in the Web design community, well know for being able to explain complex technical concepts to non-technical audiences. His most recent book is CSS3 Visual Quickstart Guide available in finer book stores everywhere.
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- Rensselaer Polytechnic Institute1996
- University of North Carolina at CharlotteEnglish, 1986 - 1992