The Search for Exoplanets: What Astronomers Know

Host Joshua Winn discusses exoplanetary science, the study of planets orbiting stars beyond the Sun. He reviews the eight planets in the solar system, which helps in understanding the thousands of distant worlds discovered in the Milky Way galaxy.

How astronomers can possibly find planets, given their faintness; direct and indirect methods of detection; discovering why a planet causes a star's position to change; a strategy for locating exoplanets without seeing them.

Exploring two indirect approaches for finding exoplanets; first, by measuring the Doppler shift in a star's color due to the pull of an orbiting planet; second, by measuring the drop in the brightness of a star as a planet transits in front of it.

Charting the history of exoplanet hunting; a false signal in the 1960s; ambiguous discoveries in the 1980s; the big breakthrough in the 1990s, when dozens of exoplanets turn up; astronomers find planets unlike anything in the solar system.

Investigating 51 Pegasi b, the first planet detected around a Sun-like star; it is roughly the size of Jupiter, but in an orbit much closer to its star than Mercury is to the Sun; probing the characteristics of these "hot Jupiters".

The standard theory of planet formation is based on the solar system; questioning whether this view requires revision based on the existence of misplaced giant planets; comparing competing theories that try to resolve this conflict.