This is Scientific American 60 Second Science.

I'm Christopher in D'Artata.

Got a minute?

How heavy is the Milky Way in comparison to its neighbor galaxy, Andrometer?

Well, depends how you calculate it. In 2006, one group

of astronomers figured the Milky Way was twice as massive as Andromeda, a 2009 estimate even

the score, calculating that the two galaxies are equal in mass.

Now a new formula suggests we're only half the mass of Andrometer.

To come up with that number, astronomers first measured the speed and distance of galaxies between

three and ten million light years away.

That allowed them to calculate the deformation of space time and thus the mass of our stellar

neighborhood, aka the local group, a group of more than 50 galaxies in which the

Milky Way and Andrometer dominate. They deduced the center of mass between the

two heavyweights and found that Andrometer may indeed be twice as massive as the Milky Way. The results are in the monthly

notices of the Royal Astronomical Society. The researchers say this new model might be more accurate than

past ones, because it accounts for dark matter far from each galaxy's center

assuming the data is right that is. Well I never bet money on anything because you know I'm

aware of all the uncertainties and approximations.

Lead author Jorge Pena Rubia of the University of Edinburgh.

One year from now, two years from now, some clever guy will come and say,

hey, you forgot to include this. Actually, when you do, everything changes and then you

will have to accept that. For now, we'll just have to accept that we live in the wimpier of the

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