Milky Weigh: Galaxy in kg is...

Ever wondered how much stuff is in our galaxy, the Milky Way?

Well, wonder no longer. It is the equivalent of 700 billion of our solar system's Suns, according to astrophysicist Gwendolyn Eadie, who drew up the calculations for a paper that she delivered this week to Canada's Astronomical Society.

She came up with the figure by measuring the velocities and positions of globular star clusters that orbit the Milky Way. The total velocity of such a cluster has to be measured in two directions: one along our line-of-sight, and another across the plane of the sky. That's not an easy thing to do.

And how much mass is in our Sun? Answer: two nonillion kilograms. And how much is two nonillion kg? Well a nonillion, for those who don't know, is a two with thirty zeros. So quite big.

You can turn all that into more sensible units here. ®

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