The Technique that Kepler is Using to Look for Habitable Planets

The Kepler spacecraft precisely measures the light variations from thousands of distant stars, looking for a moment where the light will change.  This light change could signify a planet.  

Kepler has a telescope that will focus on the stars that are as large as our Sun.  These are the stars that we think may have planets orbiting them.  If these stars do have a planet orbiting them then there should be a time where the planet is blocking our solar system’s view of the star.  This is known as a transit.

Three or more transits of a given star all with a consistent period, brightness change and duration provide a rigorous method of detection and confirmation.  Orbital period can be determined from the time between transits. Orbital size can be determined from the mass of the star and the length of time between transits, and temperature from the planet’s orbit.

The results from this data can be used to calculate the fraction of stars that have planets, as well as the different planetary sizes and orbits for many different types of stars. These results are especially exciting because they will tell us how often planets occur in the habitable zone of other stars.  

9 thoughts on “The Technique that Kepler is Using to Look for Habitable Planets”

  1. It’s not really correct to say “If these stars do have a planet orbiting them then there *should* be a time…”. For each star and planet, there is a relatively small chance that the planet will transit the star. For example, for a distant observer to see the Earth pass in front of the Sun, he/she must be located in a narrow band, less than 1/4 deg above or below the Earth’s orbital plane. This covers only about 6% of the sky. This is part of the challenge of Kepler, and the best reason to survey so many stars.

    This mission looks at stars that are medium-far away. This gives a statistical estimate of the likelihood that any given star will have planets like ours. With this vital information, we can turn our attention to stars that are much closer to us, and with greater confidence, design a mission like TPF ( that could see their light directly, measure atmospheric spectra, and hopefully find evidence of photosynthesis and other biological processes.

  2. Why are we attempting to find planets in other galaxies when they are so far away, when we should be looking within our own galaxy? Travel, if a potential earth like planet is found, would be more feasible within our own back yard than across the cosmos. Would it not?

  3. And for the galary who is perpendicular to Kepler? There could be 300 planets, and if the orbitals of em is perpendicular too? They won’t pass in front of the star to blind Kepler, how can we see them?

  4. I was having a reoccurring nightmare of me being shot out of the solar system, with nothing left behind but precious metals such as gold and silver. As I get close to Pluto, my Father turned me back like a commet, not an astroid. I was able to feel the sun’s heat again.

  5. Isn’t there some sort of radar that could send out a strong enough signal to detect planets close to our system?
    Same concept as using the disruption of light off of a star to tell if and how many planets are in orbit around that star.
    No, Never mind. It couldn’t possibly work,
    Or we could try and take images following a guesstimated orbit outside of ours. try to find some light disruption in the photos taken from Hubble? It’s pretty much the same Idea.

  6. if you look at a panoramic photo of stars surrounding our systam,
    You could probably see a pattern of disruption in the light
    that would indicate planets between us, thus discovering plannets
    or other large objects in our system that we might be unaware of.
    And Maybe we could a nuclear powered flash of light to detect
    objects as well. You could bounce the signal into the unknown
    in a direction that when returning, the signal would be in the direction be received by satellites as the earth continues it’s orbit around the sun. So send a huge concentrated light and then catch what ever is left bouncing back just like radar and the ocean.

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