## Second home for Human, if not already occupied – Kepler 22b

Starting with a Good News 🙂 A new twin of Earth has been found! Kepler (a mission by NASA lauched in 2009 to search for exoplanets) has just (on 5th Dec 2011) confirmed an exoplanet in the habitable zone. By habitable zone, I mean the zone where a planet can reside having water in its liquid form and atmosphere dense enough to keep it warm. Staying 600 lightyears away and named by the Earthlings as Kepler 22b (I hope they find a better name soon), it is almost 2.4times the radius of earth with temperature of 22°C, orbiting a G-type main sequence star which is just a bit smaller and dimmer than our sun with a period of 290 days. Though it’s mass has not been determined yet but they have been able to put up a upper constraint to it’s mass limit as 36 times Earth Mass (1$\sigma$) – hence safely keeping it in the Planetary Mass Regime.

A Comparison of Kepler 22b and Earth

The planet has been discovered by the most popular and interesting exoplanet-hunt technique called as Transit Method. If we look at a star, we see a constant brightness, but the moment a planet transits i.e. comes in our line-of-sight, we see a dimming of the brightness, the amount of dimmness being decided by the size of the planet revolving around the sun. Of course there may be false alarms – and hence Kepler waits to see three timely transits before tagging it as a confirmed planet. Here is the Kepler 22b Real Datas on Light Curve that I got from Ames NASA website:

The three red-marks show the points of three transits - first one being the raw data and the second was a bit processed!

Folded Light-Curve of Kepler 22b

The result has been published based on the three transits observed in the 22-months period between May’2009 and March’2011 and finally we have a twin earth which is the only one till now where we can hope to colonise one day if it is not occupied yet. Now the time is for SETI to concentrate on this region and see if there is some hope of having another species there. As told by SETI during the Press Conference, they will be focussing right now mainly in the 3.46cm (Emission Line of 3He+ ion) which has been proposed by Scientists Rood and Bania from Boston University as an obviousl frequency for interstellar communication.

After the spin-flip of Hydrogen Line at 21cm, this is the second-most simplest spin flip possible. Hydrogen being the most abundant eleent in the universe, they have proposed that if the extraterrestrial species are intelligent than they wont contaminate the 21cm region and will keep it solely for the study of the universe and hence moving on to 3.46cm for communication purposes. SETI says that if they do not get the hoped response at 3.46 cm then they will move on to other frequencies of microwave window.

Here is the Press Conference Video of the Discovery of Kepler 22b from Ames NASA :