Man's Next Migration

More exoplanets, but where is Goldilocks?

Almost nine months after Kepler space telescope launched to space, scientists reveal the first five extrasolar planets discoveries that hopes to inspire us that habitable exoplanets are indeed on the way. Although these exoplanets were not really the type that Kepler was created for to detect, the success of finding them proves that scientists are finally on the verge of nailing the first habitable exoplanet.

Kepler, the so called planet-hunter, was launched in March 7, 2009 after several delays due to NASA budget cuts. Its mission is to find any earth-size exoplanet that lie within the habitable zone of stars, the well-known Goldilocks planet. Unlike the Hubble space telescope, Kepler's gears were fine tuned to detect smaller planets and possess a wider field of view for detecting planetary transits, an event where an exoplanet passes in front of its star. Kepler, however, has the opportunity to observe it a couple of times more than Hubble. In this way it observes the the degree of reduction of brightness of the star from whence the diameter of the exoplanet is derived.

Such is the promise that when NASA scientists finally announced that they are going to reveal Kepler's initial results in the American Astronomical Society's 225th meeting early this January, a torrent of news filled internet sites and blogs as well as other media. Out of the five exoplanets announced, only one captured further interest, that of the “styrofoam” planet, and it was nowhere near the earth-like expectation. But we have to really give them credit for this, after all, it was reported that Kepler was able to sift through 175 probable planetary systems wherein there numerous false positives, binary stars that kept eclipsing each other and appearing almost similar to planetary transits. That in itself is a rather unique achievement in such a short span of time.

All of the exoplanets were deemed to be hot and gaseous Jupiter-like planets, with masses ranging from 25 to 670 times that of the earth. The largest is named Kepler-7b, the “styrofoam” planet, that has a density one-sixth that of water. Scientists speculate that the size of Kepler-7b and its very low density may be the result of the planet heating up. After all, most of these planets orbit very close to their parent stars and that they circle around it in less than five days!

So, where are our earth-size exoplanets, Kepler? The reason why Kepler was able to detect these five exoplanets was because of of their quick orbital periods allowing planetary transits several times in a 43-day period. Since Kepler depends on the frequency of these planetary transits for accurate measurements, scientists estimate that it will take about three years worth of recorded observations. Why? Consider that our own planet revolves around the sun for one year. A similar planet to our own must have almost the same orbital period with the main sequence of stars similar to our own Sun. Kepler has a lot of time to wait between periods.

The good news is that because of its rather wide field of view and its current orientation that points to the star systems that are the same distance from the center of the galaxy as our own Solar System, we have a much greater chance at finding an earth-sized planet orbiting within the “goldilocks zone”.

Aside from Kepler's efforts, during the same conference astronomers announced that they were able to spot an “super-earth” exoplanet four times the size of earth using the Keck I telescope in Hawaii. Initial observations indicate that the exoplanet orbits its star once every four days and has extreme temperatures on its rocky surface akin to a blast-furnace. It is located 80 light years away in the Hercules constellation.

The continuing combined efforts of astronomers and space telescopes is encouraging. We must understand that planet-hunting is not just about looking at the sky and peering into space in any direction. Space is huge. Even if we come up with dozens of space telescopes that can look in all directions, the depth of the void is staggering such that one short glimpse could yield thousands of suns. With the Kepler spacecraft focusing on a specific part of the sky and earth's powerful telescopes on the chase, the Goldilocks planet may soon be discovered. Somewhere in space, light years apart from us, is a planet that can harbor life. That possibility itself is reason enough to keep searching.

References:

The Exoplanet Explosion. Jeff Foust. The Space Review.  Accessed 18-Jan-2010
Kepler Spacecraft Spots 5 New Exoplanets. John Matson. Scientific American. Accessed 18-Jan-2010
Astronomers spot second smallest exoplanet. PhysOrg.com. Accessed 18-Jan-2010
215th AAS Meeting — Washington, DC. American Astronomical Society. Accessed 18-Jan-2010
Kepler Mission. Wikipedia. Accessed 18-Jan-2010