Editing Newsletter/Fall 2008 (section)

== When Planets Collide ==

compiled by [[herbalsheila]][[Image:BD_20_307_collision.jpg|right|400px|thumb|Artistic rendering of an Earth-like planet colliding with another with its binary star nearby.]]

Astronomers at UCLA, Tennessee State University, and the California Institute of Technology are reporting about a new space phenomena; two planets in a mature solar system named BD+20 307 have recently collided some 300 light years from Earth.

"It's as if Earth and Venus collided with each other," says Dr. Benjamin Zuckerman. Astronomers have never seen anything like this before. Apparently, major catastrophic collisions can take place in a fully mature planetary system."

"If any life was present on either planet, the massive collision would have wiped out everything in a matter of minutes; the ultimate extinction event," said astronomer Gregory Henry. "A massive disk of infrared-emitting dust circling the star provides silent testimony to this sad fate."

Benjamin Zuckerman, a professor of physics and astronomy, Gregory Henry, an astronomer at Tennessee State University and Michael Muno, an astronomer at Caltech have all been studying this solar system. What they found was startling.

The star itself is in the constellation of Aries, and referred to as BD+20 307. It is surrounded by 1 million times more dust than is orbiting our own sun. The astronomers gathered X-ray data using the orbiting Chandra X-ray Observatory and brightness data from one of TSU's automated telescopes in southern Arizona, hoping to measure the age of the star.
[[Image:Moon_formation.jpg|350px|left|thumb|Artist's rendition. Could this have been the way Earth's moon was formed?]]
Expecting to find that BD+20 307 was relatively young, perhaps only a few hundred million years old due to its dust ring signaling what they thought would be the final stages in the formation of the planetary system, they were shocked to find that the system is a close binary star as found by astronomer Alycia Weinberger of the Carnegie Institution of Washington. 
 
A binary star is two stars that closely orbit each other around their common center of mass. 

This discovery changed everything they had previously conjectured based on their observations. More data compiled using TSUA's automated telescope in Arizona was used to analyze this binary system. The new data showed that BD+20 307 is two stars similar in mass temperature and size to our own sun, with an orbit about their common mass of every 3.42 days. Its age is now thought to be comparable to our own system, several billion years, and more stable and mature than previously thought.

"The planetary collision in BD+20 307 was not observed directly but rather was inferred from the extraordinary quantity of dust particles that orbit the binary pair at about the same distance as Earth and Venus are from our sun," Henry said. [[Image:When_Worlds_Collide_Book_Cover.jpg|right|250px|thumb|Original book cover published 1932 by Frederick A. Stokes]]
"If this dust does indeed point to the presence of terrestrial planets, then this represents the first known example of planets of any mass in orbit around a close binary star."

This dust surrounding this particular binary star orbits the system very closely where dust cannot survive very long. Large pieces of debris are reduced to dust and smaller pieces are then pushed away by stellar radiation emitted by the stars they obit. Therefore the dust forming collision had to have taken place more recently. 

Francis Fenkel, another astronomer who assisted in gathering the newer data, says that this poses two very interesting questions. How do planetary orbits become destabilized in such an old mature system and could such a collision happen in our own solar system?

In the 1932 novel, "When Worlds Collide," by Philip Wylie and Edwin Balmer, twin planetary bodies orbiting each other crash into Earth, causing massive destruction to the human race and was the first in a long line of novels and films about various asteroids and other space debris causing an apocalypse on Earth. 

Zuckerman says there is no such evidence of any passing planetary body of any kind. However there is evidence that such an occurrence may have happened within our own solar system.
[[Image:Rocket_build_Worlds_Collide.jpg|325px|left|thumb|The escape rocket being built from the 1951 film 'When Worlds Collide' directed by Rudolph Mato]]
Many astronomers believe our moon was formed from the grazing collision of two planetary embryos; the young Earth and a body about the size of Mars, a crash that created tremendous debris, some of which condensed to form the moon and some of which went into orbit around the young sun," says Zuckerman.  "By contrast with the massive crash in the BD+20 307 system, the collision of an asteroid with Earth 65 million years ago, the most favored explanation for the final demise of the dinosaurs, was a mere pipsqueak."

Gregory Henry further notes that, "The stability of planetary orbits in our own solar system has been considered for nearly two decades by astronomer Jacques Laskar in France and, more recently, by Konstantin Batygin and Greg Laughlin in the U.S.A. Their computer models predict planetary motions into the distant future and they find a small probability for collisions of Mercury with Earth or Venus sometime in the next billion years or more. The small probability of this happening may be related to the rarity of very dusty planetary systems like BD+20 307."

Ironically, no one mentioned our nearest planetary neighbor Mars.

It is doubtful that there is cause for alarm for us, thankfully. We won't have to evacuate our homes for any rocket ships leaving Earth's orbit. Though you certainly may continue to carry any emergency kits with you, it may be advisable to leave your astronaut suits at home.