Hubble Weighs In: Pinning down an extrasolar planet’s mass

Using a decades-old technique, astronomers have precisely measured the mass of a planet outside our solar system. The measurement reveals that the unseen planet, which orbits a star just 15 light-years from Earth, weighs between 1.9 and 2.4 times the mass of Jupiter. Previous estimates placed the planet’s mass between 1.9 and 100 times that of Jupiter.