Saturday 18 April 2009

Kepler


Hi

As I'm sure you are aware Kepler NASA's planet finding space observatory as recently been launched. And as now opened it's mirror shield to get it's first look at what it will be observing. As seen above.
Kepler as I have said is a NASA mission, that is designed to search for extrasolar planets. And maybe just maybe find something the size of the earth. To do this Kepler will sit and stare at patch of roughly 100,000 stars , in the constellation of Cygnus. Kepler will watch these stars light output and wait for the tell tale light dip that tells us a planet is transiting the star. Hopefully at the end of it's estimated 2 year mission, there won't be 300 planets known to us like now but nearer a 1000!
The discovery of planets outside are solar system (hence the name extrasolar) is a reasonably recent discovery. The first extrasolar planet was discovered in 1995, orbiting around the star 51pegasis. It is a large planet roughly 3 times the size of Jupiter (largest in solar system). And is also oddly very close to it's parent star and, therefore very hot it is classed as a hot Jupiter. 51Peg was discovered using the wobble method. The wobble method is a method of finding planets without being able to see the planet directly. What happens is as the planet orbits the star it's gravity tugs at the star causing it to wobble. It is only a very slight wobble, which tells you why we have mainly discovered large planets, the bigger the planet the bigger the wobble. From this indirect means planet hunters can infer the size of the planet and how close it orbits.
Kepler however is using a different method the transit method. With the transit method as well as being able to detect the planet, find it's size and orbital distance. You are able to see what chemicals constitute the planetary atmosphere, by checking the spectra of the light given of by the star. If you already know what is in the stars atmosphere you can infer that what shouldn't be there is from the planet.
This method however does have a draw back for Kepler. Because Kepler is observing these stars face on (from are point of view). Any planets that orbit over the pole will be invisible to it's instruments. However with a 100,000 star field this seems to be compensated for.
The holy grail of planet hunting is not finding hot jupiters, but finding a earth like planet. As yet we have not achieved this goal, we have come close Glise 5981 as a trio of planets 1 five times the size of Earth. Although with Kepler it might be possible to find planets slightly bigger than Earth. The true achievement of finding a planet the same size as Earth with an atmosphere breathable, water oceans and life will have to wait. But when it does I don't think I will be exaggerating when I say it will be one of the greatest discoveries in Astronomy. It will show us are planet is not unique but part of a bigger picture and, if this planet as life on it will show us we are not alone in the Universe!
Thanks for reading
Kyle


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