Artists impression of Hot Jupiter around another star

On March 6, 2009, the Kepler space telescope was launched from Cape Canaveral with a primary mission to find Earth sized planets in a habitable zone around stars similar to our own by continuously and simultaneously observes more than 150,000 stars. Kepler’s instrument, has measured hundreds of possible planet signatures which are currently being analyzed. Today it was announced that it has discovered its first five new exoplanets, or planets beyond our solar system.

According to William Borucki of NASA, the principle investigator, “These observations contribute to our understanding of how planetary systems form and evolve from the gas and dust disks that give rise to both the stars and their planets,”… “The discoveries also show that our science instrument is working well. Indications are that Kepler will meet all its science goals.”

So far the planets founds are very hot and orbit close to their stars which is similar to previously found planets. What is very promising is the fact that the discoveries are based on approximately six weeks’ worth of data collected since science operations began on May 12, 2009. Clearly Kepler is likely to make further and more important discoveries before its mission ends in November 2012, although NASA has made a career or extending missions, so it may last longer. The main aim is to find an earth sized planet which orbits in a zone around a star that would allow for liquid water to flow on the surface. This means that the planet would have an orbit of months or longer, so to find such a planet and to verify it would take a couple of years even if a candidate was identified today.

There are a number of techniques used to detect exoplanets, and Kepler looks for the signatures of planets by measuring dips in the brightness of stars. When planets cross in front of, or transit, their stars as seen from Earth, they periodically block the starlight. The size of the planet can be derived from the size of the dip. The temperature can be estimated from the characteristics of the star it orbits and the planet’s orbital period.

The Transit Method for finding exoplanets

According to NASA the 5 planets discovered are known as “hot Jupiters” because of their high masses and extreme temperatures, the new exoplanets range in size from similar to Neptune to larger than Jupiter. They have orbits ranging from 3.3 to 4.9 days. Estimated temperatures of the planets range from 2,200 to 3,000 degrees Fahrenheit, hotter than molten lava. All five of the exoplanets orbit stars hotter and larger than Earth’s sun.

Optical Paths within Kepler

Kepler is watching, nearly continuously about 156,000 stars a little north of the plane of the Milky Way between Vega and Deneb. The satellite will keep watching these stars nearly 24/7 for at least 3½ years, in order to catch at least three transits of any luckily aligned planets that are in wide, Earth-like, 1-year orbits. Its a good start….

Kepler Field of View