Meet Kepler, the Extraordinary Exoplanet Hunting Telescope


If you’ve never heard of NASA’s Kepler Telescope, or perhaps only have a passing familiarity with the project, then you’re in for quite a pleasant surprise. The telescope’s mission, which was launched in 2009 under NASA’s Discovery Program, is to search for Earth-sized exoplanets in relatively small sections of the Milky Way in order to find those which fall into the sweet spot known as the habitable zone.

Even those of us who have followed the mission for years are continually impressed by NASA’s findings. To date, the telescope has found 2,330 confirmed exoplanets, another 4,706 planet candidates, and 2,165 eclipsing binaries.

An exoplanet, put simply, is one that orbits a star other than our own, and the habitable zone is the Goldilocks region – not too hot, not too cold – where liquid water could be found. The reason this is important is because if any significant life is out there in the galaxy, that’s where it will be found.

Eclipsing binary stars are cool too because they can be used to measure the distances to external galaxies, which is more accurate than the standard candle method based on a star’s luminosity. All of this basically boils down to one fine point; the more information NASA has, the more likely it will be that they find what they’re looking for.

While the The Kepler Space Observatory may technically be a telescope, it shares little in common with the plastic optical tube you got for your ninth birthday. The 4.7m long, 1,039kg spacecraft is equipped with a Schmidt catadioptric camera with a 0.95m front corrector lens, a 1.4m primary mirror, and 94.6 megapixels. This may all sound like meaningless technical jargon, but when you break it down, it comes out to the largest camera ever launched into space. Aside from a handful of mechanical malfunctions, which are common in virtually all spacecraft, the Kepler telescope has worked exceptionally well.

To know just how well it has worked, all you have to do is look at the numbers. Kepler uses a photometer to analyze approximately 145,000 stars in a single field of view, looking for periodic dimming, which is caused by astronomical transit (when one celestial body crosses in front of another).

This information then goes through a long and headache-inducing process involving raw light curves, signal analysis, and words NASA probably just made up to confuse the rest of us, all to rule out a false positive.

So far, there have been 2,330 confirmed exoplanets, with 44 of them habitable (15 Earth-sized and 29 superterran). Experts have estimated the total number of habitable planets in the Milky Way at approximately 40 billion, leaving quite a lot of work to be done.

NASA plans on continuing the mission until 2019, or at least until the on-board fuel supply has been exhausted, which should be some time in 2018. But even after Kepler goes offline for good, the Discovery Program will continue searching the skies with its low-cost, exploratory missions, such as; GRAIL, InSight, Lucy, and Psyche.

Check out’s great infographic about the Kepler Space Telescope below.