Animation: Dizzying Dance of the Kepler Candidates
Thursday, August 16, 2012
News Feature

(Written by Christine Pulliam, Smithsonian Astrophysical Observatory, for Smithsonian Science, a website featuring highlights of scientific research at the Smithsonian Institution.)

Have you ever wondered what it would look like if more than 2,000 planets circled a single star? Wonder no longer, because here's the video. (It works best if you click the full screen icon to the right of "HD" at bottom.)

This scientific visualization is much more than a dizzying dance of whirling worlds. It shows 2,299 planets found by NASA’s Kepler planet-hunting spacecraft. All of the planets are drawn to scale with accurate sizes, orbital periods, and orbital distances relative to the star. (The large white circles represent the orbits of Mercury, Venus and Earth on the same scale.)

The video was created by Alex Parker, a planetary scientist at the Harvard-Smithsonian Center for Astrophysics. "I wanted to convey the astounding number of planet candidates Kepler has found in a way that would really impact the person watching this video," Parker said.

The orbs in the video represent the majority of planet candidates identified by Kepler to date. Astronomers refer to them as "candidates" because some of the signals will prove to be false positives. However, researchers expect that most will turn out to be real worlds.

These planet candidates actually orbit 1,770 stars. (Some stars have more than one planet.) The worlds range in size from 1/3 to 84 times the diameter of Earth. Colors represent their estimated temperatures, with red indicating the hottest and blue the coldest planets.

Kepler finds planets by looking for a star to dim slightly as the planet crosses in front of it, which is known as a transit. Watching the video, you'll notice that there are always transits happening. That’s because Kepler is watching so many stars that even though transits are rare and fleeting, it will always see several occurring at any moment in time.

Amazingly, up until a couple of decades ago, we didn't know for sure that any planets existed beyond our solar system. And yet in all the time we looked, they were always there waiting to be found -- hiding in plain sight.