Our planet Earth is situated in the galaxy known as The Milky Way. The closest, visible, neighboring galaxy is Andromeda. To find out the weight of a galaxy is difficult enough, but try comparing two of them to see which one is heavier? That is a real science project undertaken by researchers at Carnegie Mellon University.

Matthew Walker published a new paper demonstrating a new method that they have developed to measure galaxies. The team of researchers headed by Walker first gathered data available on the Local Group of each galaxy. The Local Group includes all those systems that lie in and right outside an area.

Then they combined their knowledge of gravity and expansion  to arrive at the mass of each galaxy. By studying two massive galaxies that are close to each other and the galaxies that surround them, we can take what we know about gravity and pair that with what we know about expansion to get an accurate account of the mass contained in each galaxy, said Walker.

The mass was calculated to include ordinary, visible matter and the invisible dark matter in the two galaxies. It was found that Andromeda had twice as much mass as the Milky Way. Incidentally in both the galaxies 90 percent of the mass was made up of dark matter as per the findings of the science project.