Astronomers Estimate Weight Of Milky Way Using Data From Hubble And Gaia Space Telescopes

This artist's impression of the Milky Way depicts the positions of the globular cluster used in the recent study of the galaxy's mass.  ( ESA/Hubble | NASA | L. Calçada )

The Milky Way is our galactic neighborhood, but there are still plenty of mysteries in its depths. Now, scientists have solved one of the riddle of the Milky Way's weight by combining fresh data from the Gaia mission and the Hubble Space Telescope.

The team's efforts resulted in the most accurate approximation of the galaxy's weight.

The galaxy weighs in at about 1.5 trillion solar masses within a radius of 129,000 light-years from the center, according to a release from the European Southern Observatory.

Beating the Uncertainties

For a long time, scientists were divided about the actual weight of the galaxy, due to the varying efforts used to measure the distribution of dark matter.

Dark matter makes up 90 percent of the galaxy's mass, but European Southern Observatory's Laura Watkins reveals that it is not possible to see and observe dark matter directly, which made it difficult to get an accurate figure for the scientists.

In these latest calculations, the team measured the velocities of the star clusters orbiting the galaxy instead.

"The more massive a galaxy, the faster its clusters move under the pull of its gravity" N. Wyn Evans of the University of Cambridge in United Kingdom explains. "Most previous measurements have found the speed at which a cluster is approaching or receding from Earth, that is the velocity along our line of sight. However, we were able to also measure the sideways motion of the clusters, from which the total velocity, and consequently the galactic mass, can be calculated."

A Joint Venture

The NASA/ESA Hubble Space Telescope and the ESA Gaia mission joined forces to provide the recent and most accurate estimate of the Milky Way's mass.

In the statement from ESA, the organization called it "a striking example of multi-mission astronomy."

Data from the Gaia mission is key with measurements of these globular clusters extending up to 65,000 light-years away from Earth, while the observations from Hubble added data from globular clusters as far as 130,000 light-years from the planet.

Roeland P. van der Marel of the Space Telescope Science Institute calls the team lucky for having access to informative data from two different sources. He adds that it would have been impossible to accomplish without these two telescopes.

Now, the results of the research on Milky Way's mass can open up to new answers to many astrological questions.

"One reason it's important to measure the Milky Way is that we live here, it's the closest galaxy we have," Watkins says in a report from The Guardian. "A lot of the time, we try to understand the universe by putting it in context of the Milky Way."

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