During 9.6 years in orbit, the Kepler space telescope observed more than half a million stars and discovered more than 2,600 planets. See the mission by the numbers.

NASA Associate Administrator Thomas Zurbuchen and TESS Project Scientist Padi Boyd discuss Kepler's legacy, the search for life and the big question: Are we alone?

The stars TESS studies are 30 to 100 times brighter than those the Kepler mission and K2 follow-up surveyed, enabling far easier follow-up observations with both ground-based and space-based telescopes. TESS will also cover a sky area 400 times larger than that monitored by Kepler.

NASA's Kepler mission revealed that there are more planets than stars in our galaxy. It opened our eyes to diverse worlds – some entirely unlike planets found in our solar system.

The Kepler space telescope will remain for decades in orbit around the Sun, weaving in and out of Earth’s orbital path.

Launched in March 2009, NASA’s first planet-hunter confirmed more than 2,600 planets beyond our solar system. "Many stars have planets. A lot of these planets are Earth-sized. That's Kepler's legacy. This new knowledge that we have about planets around other stars."

Send your love with a habitable planet valentine.

Tell someone they're unique, with our Earth valentine.

Keep your Valentine close with a tidally-locked planet, that always faces its star.

Celebrate your rocking single status with a rogue planet, the world without a star.

For Valentine's Day, give the tight-knit Kepler-11 to your faves.

Celebrate Valetine's Day with a hot Jupiter that tightly hugs its star.

Meet the astronauts, mathematicians, and directors leading NASA's most innovative missions to space.

Kepler-186f is the first Earth-size planet discovered in the potentially 'habitable zone' around another star, where liquid water could exist on the planet's surface. Its star is much cooler and redder than our Sun. If plant life does exist on a planet like Kepler-186f, its photosynthesis could have been influenced by the star's red-wavelength photons, making for a color palette that's very different than the greens on Earth. This discovery was made by Kepler, NASA's planet hunting telescope.

This artist's concept shows what the weather might look like on cool star-like bodies known as brown dwarfs. These giant balls of gas start life like stars, but lack the mass to sustain nuclear fusion at their cores, and instead, fade and cool with time.

Artistic rendering of a planet's transmission spectrum

Researchers are getting to know some of our sun's closest and smallest neighbors.

Astronomers detect lowest-mass planet around a star like the sun found using direct imaging techniques.

In this artist's impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to "blink" every 93 days.

For the first time since exoplanets, or planets around stars other than the sun, were discovered almost 20 years ago, X-ray observations have detected an exoplanet passing in front of its parent star.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have taken the first ever image of the snow line in an infant planetary system.

For a tidally locked planet there is no day or night, only freezing darkness on one side and burning constant sunlight on the other. The terminator zone is bathed in constant twilight and would likely be the only place on the planet to be potentially hospitable.

Do other planets beyond our solar system, called exoplanets, also host life forms?

Hubble finds a deep-blue exoplanet that may feature pummeling showers of glass rain moving at 4,500 mph. Care to visit?

This image from ESO's Very Large Telescope (VLT) shows the newly discovered planet HD95086 b, next to its parent star.