There was an announcement today that the Kepler mission has confirmed the existence of a planet that is the most Earth-like that has ever been discovered. The planet was given the name Kepler-22b and was discovered using the transit method where the Kepler instruments look for slight dimming of the stars brightness which indicates a planet has passed between our viewing point and the star.
From the Exoplanet iPad app, here are some screen shots of the pertinent information
This is truly an amazing discovery. The star’s size is almost identical to Earth’s (98% as large as our Sun), the orbital period of the planet is slightly less than ours (290 days versus 365 for Earth) and the distance from its star is close to our (85% of Earth’s). The planet is much larger than Earth as can be seen from the picture above but that is the only major divergence it has from the little blue orb we call home.
Is there oxygen and water on this planet? Is there an atmosphere that supports life as we know it? Does the planet contain life? Right now we don’t know the answers to these questions but the average temperature on that planet should be suitable to have water in liquid form if the elements are there.
To find a planet relatively close to us, a little less than 600 light years away, is amazing enough but the fact that we can scientifically gather this type of detailed information from an object so far away speaks volumes as to how far Astronomy has advanced in the last 20 years. I will not go into the physics here on how scientists obtain this information but there is a good resource that shows the many ways we can calculate the distances to stars and galaxies. The Wikipedia page on exoplanet detection methods provides a good resource on how we can detect planets orbiting stars and the European Space Agency has another good overview of exoplanet detection methods.
We live in an exciting time where discoveries like this are being made at an amazingly high frequency. With hundreds of stars known to have planets orbiting them and over a hundred planets orbiting in the habitable zone, Science will now move to answer some of the more difficult questions I posed above. We have instruments and methods to detect elements on these planets (such as water, Oxygen, CO2, etc.) but existence of intelligent life will only happen if we detect radio signals from the planet or they receive and retransmit our signals that we send them. And with round trip times of hundreds of light years, don’t expect that discovery to happen for a while!