'Jupiter's Younger Sibling' Marks Start of Exoplanet Discovery Era

Astronomers using the W. M. Keck Observatory in Hawaii have directly captured images of AF Lep b, one of the lowest-mass planets ever discovered. The planet is about three times the mass of Jupiter and orbits a young sun-like star about 87.5 light-years away. The discovery was made using a technique called astrometry, which measures the subtle movements of a host star over many years to help astronomers determine whether hard-to-see orbiting companions, including planets, are gravitationally tugging at it. This new method of combining direct imaging with astrometry could help astronomers find extrasolar planets that were hard to find before with other methods.