When NASA scientists began planning the Kepler mission, humans didn’t know of a single planet outside of our solar system. But by the time the roving space telescope retired, on October 30, it had accumulated an impressive resume. Since its launch in 2009, it has discovered more than 2,600 confirmed planets outside our solar system, many of which are hopeful candidates for hosting alien life. The universe, Kepler proved, is home to more planets than stars.
To commemorate Kepler’s nine years of deep space exploration, NASA postdoctoral fellow Ethan Kruse created a video that shows all of the multi-planet systems Kepler uncovered from its first moments in space to its retirement on Tuesday. In the video above, the swirling dots that represent planets are colored in a way that reflects their approximate equilibrium temperatures. Deep blue planets, for example, are like our Earth, while the completely red ones consist of lava.
All of the systems are shown together at the same scale of our own Solar System. The size of the orbits are all to scale, but the size of the planets are not.
One of the most spectacular aspects of Kepler’s discoveries is the sheer variety of exoplanets because they are outside of our solar system) — those outside our solar system — that it has found. A recent analysis of Kepler’s discoveries determined that 20 to 50 percent of the stars we can see in the night sky likely have their own small, rocky planets orbiting around them in a “habitable zone” of their parent stars. These are the planets that scientists are most confident will contain liquid water, thought to be a crucial indicator of life.
“As NASA’s first planet-hunting mission, Kepler has wildly exceeded all of our expectations and paved the way for our exploration and search for life in the solar system and beyond,” Thomas Zuburchen, Ph.D., associate administrator of NASA’s Science Mission Directorate, said Tuesday. “Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm.”
Now that Kepler has run out of maneuvering fuel, it’s destined to an eternal existence of drifting in space. As of now, it’s 944 million miles away in an orbit trailing Earth. As years go by, it will be tugged in and out of Earth’s orbit, but it will never come closer than a million miles to Earth.
Kepler’s retirement, however, doesn’t mean that the search for planets is over. The torch has been passed to NASA’s new space observatory, the Transiting Exoplanet Survey Satellite. TESS will spend the next two years monitoring more than 200,000 stars for temporary drops in brightness caused by planetary transits. According to NASA, it is the “first-ever spaceborne all-sky transit survey,” an incredible planet-finding mission that unmatched by any ground-based survey.