Study: Earth Closer to Center of Milky Way Than Previously Thought

Scientists had long thought the solar system was located on a mere 'spur' of the Milky Way.

This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, left, in 3.75 billion years. (NASA)
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Earth may not be located in the center of the universe, but a new study finds that it is a little closer to the center of the galaxy than previously thought.

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Astronomers thought the solar system was located in a small "spur" of the Milky Way, a galaxy that contains somewhere between 200-400 billion stars. The center of the Milky Way likely still contains a "supermassive black hole" that the rest of the stars orbit around, but it turns out that the solar system is likely located on one of the star's "main arms" of the spiral galaxy known as the "Local Arm."

"Our new evidence suggests that the Local Arm should appear as a prominent feature of the Milky Way," Alberto Sanna, of the Max-Planck Institute for Radio Astronomy, said in a statement. "Based on both the distances and the space motions we measured, our Local Arm is not a spur. It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment."

Sanna presented his research Monday at the American Astronomical Society's meeting in Indianapolis. He and his colleagues used data from the National Science Foundation's Very Long Baseline Array, a series of 10 radio telescopes spread throughout the continental United States, Hawaii and the Virgin Islands. The array is used to track near-Earth asteroids, measure the sizes, spins and shapes of galaxies, and estimate the distance of stars from Earth.

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Measuring the Milky Way is difficult because the solar system is located inside it. To solve the problem, Sanna and his team took measurements from when Earth was located on either side of the sun, allowing them to get different perspectives and new measurements. The new finding suggested the solar system is most likely located on a major arm of the galaxy, not an offshoot of that.

The team says our "Milky Way neighborhood just went upscale," but perhaps we shouldn't get too comfortable: A NASA finding last year suggested that the Milky Way is "destined for a head-on collision" with the neighboring Andromeda galaxy.

"It is likely the sun will be flung into a new region of our galaxy, but our Earth and solar system are in no danger of being destroyed," the agency says. According to NASA, the collision will likely occur about 4 billion years from now.

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