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How Much Does the Milky Way Weigh?

By David Reneke

How much does the Milky Way weigh?

The full text of this article can be purchased from Informit.

Our home galaxy is a massive star-studded conglomeration more than 100,000 light years across. Calculating the weight of something so colossal seems beyond the realm of possibility, especially when peering from the inside out. However, Canadian astronomers at McMaster University have calculated that the Milky Way is a little lighter than previously believed, with a mass equivalent to about 700 billion suns!

Previous estimates about the Milky Way’s mass have ranged from 100 billion to 1.6 trillion times that of our own Sun, but Prof William Harris and PhD student Gwendolyn Eadie devised a novel way to measure the galaxy’s dark matter – via the invisible and undetectable.

To arrive at their current estimate, the team studied the positions and velocities of numerous globular star clusters that orbit the Milky Way. As the authors note, “the orbits of globular clusters are determined by the galaxy’s gravity, which is dictated by its massive dark matter component”.

Based on early reviews, their approach is one of the most thorough analyses to date. “With our estimate, it seems that dark matter makes up about 88% of the Milky Way’s mass,” Eadie said. “The rest of the weight are in the things you might expect like stars, planets, gas, moons and dust.”

The ultimate determination of the Milky Way’s total mass could provide scientists with clues about its...

The full text of this article can be purchased from Informit.