Kepler Project is a space telescope like no other. It stares at the same area of the sky, roughly the area of the Big Dipper, and takes picture after picture. The Kepler scope has one of the largest digital cameras ever made and all it does is record, with exquisite precision, the light arriving from the same 150,000 stars. Minute by minute, day after day, week after week, month after month, year after year.
If a planet happens to go in front of the star it will dim slightly and Kepler's camera is sensitive enough to record that. It is like a tiny eclipse or, as astronomers call it, a transit. If the dimming happens at regular intervals, it may be a planet. The amount of the dimming and the period of the dimming gives the Kepler scientists an idea of the size and distance from the star of the planet. (See
Kepler's Laws
Confirmation bias comes into this because the easiest planets to see with this method are the largest planets and those closest to their star. So Kepler's discoveries will inevitably be biased.
The cool thing is that the Kepler scientists are aware of the bias so they can factor it out. So far, they have found that planetary systems in our galaxy seem to be like our solar system, with plentiful earth-sized planets, even though the actual numbers do not say that. It's that damned confirmation bias.
This is a great project. I go onto the NASA Kepler site about once a month. It is awesomely cool, explicitly designed to find how many Earth-sized planets exist in our galaxy.
That's one of the factors in the
Drake Equation. Here's Carl Sagan describing what that is:
Kepler's very, very cool, eh?
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