It turns out that the Milky Way is much lighter than astronomers first thought.
The mass of the Andromeda galaxy, the Milky Way’s “twin” and nearest galaxy, is twice as much as the Milky Way’s, according to the National Geographic. Andromeda is 2.6 million light-years away.
Andromeda and the Milky Way are “twins” for having similar structures, but the difference in weight is due to the amount of dark matter. Dark matter can’t be seen, but its weight can be measured.
The matter is thought to be a class of physics particle, and its weight is measured by its gravitational effects. Scientists believe that Andromeda has twice as much dark matter than the Milky Way, giving it a much heavier mass.
“We always suspected that Andromeda is more massive than the Milky Way, but weighting both galaxies simultaneously proved to be extremely challenging,” said Dr. Jorge Penarrubia who led the team of scientists, according to the Daily Mail. “Our study combined recent measurements of the relative motion between our galaxy and Andromeda with the largest catalogue of nearby galaxies ever compiled to make this possible.”
“We don’t understand at all what dark matter might be and there are many theories. What our research could do is help explain more about how this elusive material behaves.”
Late July and early August are the best viewing times for the glow of the Milky Way’s band of lights while the moon is in its new phase.