Audio Guide：

Since the 1990s, astronomers have discovered many exoplanets. Within over a decade, over 500 hot Jupiters were found with the radial velocity method. In 2009, NASA’s Kepler Spacecraft discovered even more extrasolar planets using transit photometry. Many of these exoplanets are similar to Earth in mass while others are super-Earths several times larger than Earth in size.

You can learn the number and types of extra-solar planets discovered by scientists so far.