Today, astronomers voted to demote Pluto of its planet status after 76 years of equal status with the Big 8… can you imagine how many books and model solar system toys now have to be reproduced?

2500 scientists meeting at the the International Astronomical Union (IAU) in Prague debated and finally approved a definition of the word “planet,” redefining Pluto as “dwarf planet” and leaving only 8 major planets in the solar system.

Sadly, Xena didn’t make the cut either after much speculation that it would. According to the IAU

In short, a “planet” is now defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit…

A dwarf planet, according to the new definition, is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.

Pluto was demoted because its orbit is eccentric compared to the other 8. At points, it’s actually closer to the sun than Neptune.

So now there are 8 planets and 3 dwarf planets (Pluto, Ceres, and 2003 UB313 aka Xena).

When Xena (UB313) was found in July 2005 by Caltech’s Mike Brown and colleagues, it changed the way astronomers thought about what planets are. Next week, the International Astronomical Union will clarify the definition of a planet and either upgrade Xena to planet status or downgrade Pluto to just another object in the Kuiper Belt. It’s also possible that the asteroid Ceres and Pluto’s moon Charon will become planets.

According to Brown’s op-ed piece in today’s NY Times

If you were to look unemotionally at the hundreds of thousands of bodies orbiting the sun, only eight (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) would clearly distinguish themselves by their large sizes.

The remaining objects, which are significantly smaller, are mostly either rocky bodies in the asteroid belt between Mars and Jupiter or icy bodies in the Kuiper Belt in the distant regions beyond Neptune. Of the more than 1,000 known objects in the Kuiper Belt, 2003 UB313 and Pluto are the largest and second largest.

Since Pluto was discovered back in 1930, many kids have made models of the solar system with 9 planets. It’s become a cultural phenomenon and many people don’t want to see it downgraded.

Brown is hoping that the committee keeps Pluto and upgrades Xena. I’m rooting for it too.

But the weird part is that Xena reflects 86% of sunlight whereas Pluto only reflects 60%. The only known object in our solar system known to have a higher reflectivity is Saturn's moon Enceladus.

Scientists have proposed two scenarios to explain Xena's high reflectivity. In one, a jet of methane leaks continuously from Xena. The methane jet freezes as it emerges, continually blanketing the surface with fresh snow.

What's the heat source that could drive such activity? "Beats me," says planetary scientist Rick Binzel of the Massachusetts Institute of Technology. He notes that gravitational tugs from a neighboring moon sometimes generate heat within a body, but Xena's moon is too small to do that.

Another source of heat, sunlight, would penetrate only a few tens of meters below Xena's surface and would probably have long ago depleted the reserves of methane there.

In the other model, the planet has a methane-rich atmosphere created during the portion of its 560-year-long orbit when it's nearest the sun. As Xena speeds away, the atmosphere freezes on the surface as a bright frost. However, Brown says, it's not clear that such frost would be bright enough to account for the shininess of Xena's surface.

Source: ScienceNews

That may change if the Giant Magellan Telescope is ever built. Slated for completion in 2016, this super-telescope will have up to 10 times the resolving power of the Hubble Space Telescope with its seven 27.6 foot mirror segments. The team has raised $17 million for the mammoth project that is estimated to cost about $500 million but that's not holding the project back.

For the next several years, the fate of the Giant Magellan Telescope will rise or fall on the efforts of Roger Angel. If his team fails to deliver seven enormous mirrors to the accuracy needed, the entire project will collapse.

On the bright side, if it's ever built, this telescope will hold the key to the future of astronomy.

Whoever builds the next giant telescope will own the cutting edge of astronomy for years, perhaps decades. Those astronomers - and only those - will have first crack at the very biggest questions out there. The next great telescope will help discover what 96 percent of the universe is made of, unraveling the mysteries of so-called dark matter and dark energy. For now, we know of life on just one planet around just one of the 1022 stars in the known cosmos. The Giant Magellan Telescope may be able to detect Earth-size planets around a nearby star and may even be able to identify the traces of living chemistry in exoplanet atmospheres. How our universe evolved from its simple beginnings, what it contains, what its ultimate fate may be - these are the fundamental human questions the new telescope is designed to address.

]]> http://www.sciencereport.net/2006/04/08/discovery-of-new-planets-and-the-fate-of-the-magellan-telescope/feed/ http://www.sciencereport.net/2006/03/19/a-brief-history-of-time/ http://www.sciencereport.net/2006/03/19/a-brief-history-of-time/#comments Mon, 20 Mar 2006 00:57:21 +0000 Krista http://72.249.45.163/~science/2006/03/19/a-brief-history-of-time/ One of the more fascinating books I’m currently reading is Stephen Hawking’s A Brief History of Time. It’s actually light reading for a theoretical physics book, meaning that he doesn’t lose you at any point, nor does he bore/frustrate his readers with lots of obscure math, so thus far, I’m happy with it.

A quick synopsis of the first chapter: For anyone who wasn’t paying attention in history, the ancient Greeks knew that the world was round - it wasn’t discovered to be so by Christopher Columbus - but according to the Aristotle/Ptolemy model, the earth stood stationary at the center of the universe with eight spheres surrounding it. So you had the earth. and then you had a sphere a little bit bigger than the earth that held both the earth sphere and the moon. and then you had a sphere a little bigger than that that held the earth sphere, the moon sphere and mercury. and as you went further from the earth, you traveled into the spheres of Venus, the sun, Mars, Jupiter, and Saturn, until you got to the final all encompassing sphere which held all other spheres and was where the stars resided.

Copernicus’ Heliocentric Universe
Of Course today, we know that model isn’t accurate. In 1514, Copernicus proposed that the sun was the stationary object and all other objects revolved around it. Galileo and Kepler publicly supported it and eventually contributed to the world accepting that objects could revolve around other objects that weren’t the earth and they followed elliptical paths instead of circular paths.

Newton and Gravity
Enter Newton in 1687 and his law of universal gravitation which said that each body in the universe was attracted towards every other body by a force. That force was stronger when the bodies had greater masses and when they were closer together. Gravity is what causes the moon to orbit the earth and the planets to orbit the sun. That led to Newton’s theory that the stars must be moving because if they remained stationary, eventually they’d fall in on themselves. His method of solving this dilemma was to propose that stars are distributed uniformly over an infinite space. In an infinite universe, every point can be regarded as the center because every point has an infinite number of stars in any direction away from it.

Many people put forth arguments against this infinite universe problem, specifically, if every point was infinite and static, the entire sky, even at night, should be as bright as the sun. Another argument was that the light from distant stars would be dimmed because stars closer to them would absorb the light. This would then make that matter hotter until they glowed as brightly as stars. The only way to avoid the conclusion that the entire sky should be as bright as the sun was to believe that at one point the universe had a beginning.

The Big Bang Theory
And so in 1929, Edwin Hubble proposed the Big Bang theory because in his studies, he observed that galaxies are moving away from each other, or in other words, the universe isn’t static, but expanding. Therefore, there must have been one time when the universe was infinitesimally small and infinitely dense. Time would not exist before the big bang, which was the point in time when the universe started expanding because any event before it would not effect what is currently happening. Therefore time is only relevant from the beginning of the universe onward.

Towards A Unified Theory of Everything
The goal of scientific theory is to come up with one unified theory that explains the entirely of everything. As of now, there are currently two partial theories that seem to be inconsistent with each other. The first is Einstein’s general theory of relativity which works rather well on a larger scale. The second is quantum mechanics, which works rather well on extremely small scales. Physicists are trying to combine the two partial theories into a unified quantum theory of gravity.

The planet’s existence was first discovered in July 2005 by Caltech’s Mike Brown and colleagues. Officially called 2003 UB313, the planet lies 13.5 billion kilometers from the Earth and is about 5 million times dimmer than the North Star (Polaris).

What does the planet look like?

Louis Berman, a member of the St Louis Astronomical Society and the second observer, describes what he saw as “a very dim, point-like source that could only be seen through averted vision. If you looked straight at it, you’d never see it.”Another observer, Kevin Mace, says “It looked like a faint star. It’s not visually stunning.”

(Source: New Scientist Space)