August 16 – Kepler in the sky with diamonds

Today’s factismal: NASA’s Kepler Space Telescope was declared officially unfixable today, after discovering more than 135 planets orbiting stars other than the Sun.

It is a sad day in planetology today; the Kepler Space Telescope has been declared to be unfixable and one of the most successful space missions ever has ended. Just as a moth flying in front of a searchlight will cause it to dim slightly, a planet moving in front of a star will block some of the starlight, creating a signature that can be seen if you look at it steadily. To do that steady looking, Kepler used three gyroscopes, with a fourth kept for backup. One flywheel failed last year in July, so they switched to the backup. Unfortunately, that failed in May and NASA engineers have been unable to revive either flywheel, putting an end to the mission. But what a successful mission it has been!

An artist's conception of what Kepler looks like right now (Image courtesy NASA)

An artist’s conception of what Kepler looks like right now
(Image courtesy NASA)

In the four years since Kepler’s launch, it has found 135 planets around other stars (what planetologists call “exoplanets”). Even better, it has also found evidence for another 2,935 possible planets that simply await confirmation from another telescope to be declared actual. And it has done that in a patch of sky no bigger than “two scoops” of the Big Dipper; if it were to cover the remaining sky, the numbers would be about 400 times bigger! In short, Kepler has shown beyond a doubt that planets are plentiful.

Where all of the Kepler planet candidates are (Image courtesy NASA)

Where all of the Kepler planet candidates are
(Image courtesy NASA)

And those plentiful planets cover a wide range of conditions. The largest planet found by Kepler is 18 times larger than Jupiter; much bigger, and it would have been a star. And the smallest planet found by Kepler is just half the size of Earth, or about halfway between the size of Mars and Mercury. Kepler’s planets have orbits as short as six hours and as long as 580 days. Their surface temperatures range from slightly cooler than the Earth to as half as warm as the surface of the Sun. In short, Kepler has proved that planets are not only ubiquitous, but they are amazingly varied in their environment.

Of course, though Kepler is no longer operating, the data remains. And where there is data, there are citizen scientists! If you’d like to look through the Kepler data, hunting for your very own exoplanet, then head over to the aptly-named Planet Hunters and give it a go!

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