Astronomers more accurately calculate the Milky Way's mass

Spoiler alert: It's huge.
Billy Steele
B. Steele|01.17.17

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Billy Steele
January 17th, 2017
REUTERS/Amr Abdallah Dals
REUTERS/Amr Abdallah Dals

It's impossible to arrive at an exact measurement for the billions of stars and other objects that make up the Milky Way. However, a group of astronomers say they have calculated the most accurate estimate to date. In a paper that will be published in The Astrophysics Journal, the scientists estimate the mass of the Milky Way to be 9.5 x 1041 kilograms or 95 followed by 40 zeros. For reference, that's 4.8 x 1011 times the mass of the sun. Astronomers use the so-called "solar masses" as a standard unit of measure, comparing other objects and formations to the sun.

The scientists used some super complex math and stats calculations to arrive at that estimate. More specifically, the team employed a combination hierarchical Bayesian analysis along with direct measurements of the velocity of globular clusters. Astronomers can estimate the mass of the sun by observing its gravitational pull on the Earth. The same can be done for the Milky Way by measuring its gravitational pull on those globular clusters. This new estimate includes stars, planets, moons, dust, dark matter and more that make up the galaxy.

Researchers say the key to this calculation is that they include any uncertainties in the estimate. Gwendolyn M. Eadie, a doctoral candidate at McMaster University in Hamilton, Ontario, explained to The New York Times that the methods used here could have wider implications for future research. The methods have been employed in other fields before, but they're becoming more useful to astronomers now that computers have enough processing power to handle the complex calculations.

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