Extrasolar Planets

Tuesday, July 21, 2009

Extrasolar Planets

Current mood: awake

So Liz and Drew, this is more for you since you both have expressed interest in my astronomy class, but just in case anyone else is curious, here ya go! My paper on the planets that have been found outside of the solar system thus far.

Tonya Little

Astronomy Telecourse

Paper # 2

M.Simmons

7/20/09

Extrasolar Planets




According to the NASA website, there are currently 353 known planets outside of our solar system. Of those, 241 of those are gas giants, 80 of them are hot Jupiter-like planets and 4 are pulsar planets. The first extrasolar planet discovered was in 1994 by Dr. Alexander Wolszczan. He had detected two or three planet-sized objects orbiting a pulsar in the Virgo constellation. He was able to detect them by observing the effects of the planets’ gravitational pull on the dead star. These planets would not be able to support life since they are subject to very high energy radiation from the pulsar.

However soon after that discovery came another one in 1995. Michel Mayor and Didier Queloz of Geneva found an orbiting world close to the star 51 Pegasi. They too had observed this star indirectly, using another method called the radial velocity method. After these initial discoveries, new planets were found rapidly. Just three months after the Geneva team discovery, another team from the US discovered 2 more planets. By the end of the 20th century there had been dozens of worlds discovered.

Most of these planets are strange and not like our own planets. They have short periods and eccentric orbits close to their stars. So far all of the planets have been giant planets, like Jupiter, and very unlikely to harbor any life as we know it. They also all have varying masses. More recently planets that are more like our own planets have been discovered with longer orbital periods and more circular orbits. It is believed that we have been able to make so many of these discoveries because of new technology and technological advances. However, none of these planets have actually been seen, they have just been detected to be there through their effects on the star that they orbit.

There are many different methods for detecting stars including; The Doppler shift, Astrometric measurement, Transit method, Gravitational microlensing, and Direct Detection. Over the next 15 years NASA is planning several missions that will help to find out more about new planets. The Keck Interferometer will study dust clouds around stars where Earthlike planets might be forming. The Kepler Mission, which is scheduled to launch this year, will survey our region of the Milky Way galaxy to find Earth-sized and smaller planets. This information will be able to tell us if planets like Earth are common or rare in our galaxy.

After Kepler, SIM Planetquest will be started to measure the distances and positions of stars for greater accuracy. This accuracy will help us locate planets in habitable zones around the nearby stars. Last, the Terrestrial Planet Finder will provide the first photographs of the nearby solar systems. As we are gathering these photos, we will be attempting to analyze the atmospheres of the planets looking for the 3 gases that would suggest that life is present; carbon dioxide, water and ozone. However at the same time we must keep in mind that there could be life that happens without these things, but it would not be life as we know it. Also the life we could find could be as simple as bacteria, or as complex as a civilized world. Depending on what we find with the Terrestrial Planet Finder, next could come a mission called Life Finder. This mission would be to collect spectra of the atmospheres of the planets.

Astronomers are very hopeful and optimistic that they will find an Earthlike planet that harbors life, however it could take many more years, and technological advances in order to find it. It is unlikely that we alone are the only forms of life in such a vast universe, and I personally hope that the discovery of life on other planets happens in my lifetime! It is such an amazing idea that there could be worlds full of other people somewhere out there, or perhaps even other forms of life that are nothing like us at all.

Sources:

http://planetquest.jpl.nasa.gov/

http://www.public.asu.edu/~sciref/exoplnt.htm#preface