Scientists have for the first time determined the mass of a non-transiting extra-solar planet. Artist's impression of Tau Boötis b looking at its sun (NASA) Although there have been about 800 extra-solar planets discovered so far in our galaxy, the precise masses of the majority of them are still unknown, as the most-common planet-finding technique provides only a general idea of an object’s mass. Knowing a body’s mass is essential...
