Kepler is a space observatory launched by NASA to discover Earth-like planets orbiting other stars. The spacecraft, named in honor of the 17th-century German astronomer Johannes Kepler, was launched in March 2009.

The Kepler mission is "specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets."Kepler's only instrument is a photometer that continually monitors the brightness of over 145,000 main sequence stars in a fixed field of view. This data is transmitted to Earth, then analyzed to detect periodic dimming caused by extrasolar planets that cross in front of their host star.

Kepler is a project under NASA's Discovery Program of relatively low-cost, focused science missions. Construction and initial operation were managed by NASA's Jet Propulsion Laboratory, with Ball Aerospace responsible for developing the Kepler flight system. The Ames Research Center is responsible for the ground system development, mission operations (from December 2009), and science data analysis.

Dimitar D. Sasselov (Bulgarian: Димитър Д. Съселов) (b. 1961) is a Bulgarian astronomer based in the United States. He is a Professor of Astronomy at Harvard University and director of the Harvard Origins of Life Initiative. In 2002, Sasselov led a team that discovered the most distant planet in the Milky Way known at the time.

Sasselov was born in Sofia, the capital of Bulgaria, to a scientific family. His father was an archaeologist and his mother was a horticulturist. He developed a liking for astronomy at an early age and would observe the moons of Jupiter by means of a small telescope. Sasselov finished a primary school in Nesebar and a high school in Burgas.

In the 1980s, Sasselov continued his study of astronomy at the Sofia University's Faculty of Physics. After he published a paper in international scientific journals, he was invited by the University of Toronto, who offered him a scholarship. However, Sasselov was not granted an exit visa by the Bulgarian authorities. He acquired a doctorate in physics from Sofia University in 1988; shortly thereafter, with the collapse of the Soviet Union and the communist regimes in Eastern Europe, Sasselov had the chance to eventually continue his work at the University of Toronto. In 1990, he earned his doctorate in astronomy there.