Neutron star and black hole masses in binary systems are calculable using Kepler's laws of motion, based on orbital parameters and object speeds. Merging neutron stars or black holes emit ...

It's fun to think about how we know stuff. For instance, the sun has a mass of about 2 x 10 30 kilograms. That is such an enormous mass that it's difficult to comprehend. And if it's so difficult for ...

How do we know the mass of a planet originally appeared on Quora - the knowledge sharing network where compelling questions are answered by people with unique insights. Answer by Geoffrey Widdison on ...

How heavy is the Milky Way galaxy? It may seem impossible to get a sense of it from our tiny little planet, but astronomers have their ways. Now a team has used data from Hubble and the Gaia satellite ...