Milky Way bigger and faster than once thought

Scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, US, claim the Milky Way is bigger, faster and more massive than previously thought. By using the Very Long Baseline Array (VLBA), scientists discovered our galaxy has about 50 percent more mass than earlier productions, is about 15 percent wider than previously thought, and that it is moving 15 percent faster than earlier predictions. More info at BBC News.

Tiny shifts in the frequency of the radio emission that arise because the regions are moving gave the researchers an estimate of how quickly the Milky Way rotates around its centre.

They estimate this to be about 914,000km per hour, significantly higher than the widely accepted value of 792,000km per hour.

That speed, in turn, allowed the astronomers to calculate the total amount of dark matter in the Milky Way - the invisible component that makes up the majority of the galaxy's mass.

The researchers estimate that the Milky Way contains about 50% more mass than earlier predictions - putting it on a par with the Andromeda galaxy, previously thought to be our much bigger neighbour and the largest in our Local Group of galaxies.

"No longer will we think of the Milky Way as the little sister of the Andromeda Galaxy," Dr Reid said.