The 'Great Attractor' pulling the Milky Way galaxy off course : Short Wave No matter what you're doing right now – sitting, standing, walking – you're moving. First, because Earth is spinning around on its axis. This rotation is the reason we have days. Second, because Earth and other planets in our solar system are orbiting the sun. That's why we have years. Third, you're moving because the sun and the rest of our solar system is orbiting the center of the Milky Way galaxy at over 500,000 miles per hour. If all of that isn't nauseating enough, everything in the entire universe is expanding outward. All the time.

But in the 1970s, astrophysicists noticed something strange about our galactic neighborhood, or Local Group. The whole clump of neighboring galaxies was being pulled off course at over one million miles per hour, towards something we couldn't see — the "Great Attractor." This Great Attractor sits in the "Zone of Avoidance," an area of space that is blocked from view by the stars and gas of the Milky Way. Today on the show, host Regina G. Barber talks to astrophysicist Jorge Moreno about this mysterious phenomenon: What it might be and what will happen when we eventually reach it.

Curious about other cosmic mysteries? Email us at shortwave@npr.org.

The mysterious 'Great Attractor' pulling the Milky Way galaxy off course

The mysterious 'Great Attractor' pulling the Milky Way galaxy off course

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This illustration shows the Milky Way, our home galaxy. NASA/JPL-Caltech hide caption

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NASA/JPL-Caltech

This illustration shows the Milky Way, our home galaxy.

NASA/JPL-Caltech

No matter what you're doing right now – sitting, standing, walking – you're moving.

Specifically, you're moving at least four different ways.

First, Earth is spinning around on its axis at about 1,000 miles per hour right now, or about 1,600 kilometers per hour. This rotation is the reason we have days. Second, Earth and other planets in our solar system are orbiting the sun. Our planet does that at around 67,000 miles per hour, or about 108,000 kilometers per hour. That's why we have years. And third, you're moving because the sun and the rest of our solar system is orbiting the center of the Milky Way galaxy at over 500,000 miles per hour, or 828,000 kilometers per hour.

On top of all that, you're moving because the entire universe is expanding outward. All the time.

But in the 1970s, astrophysicists noticed that something was off about our galactic neighborhood, or Local Group. The whole clump of neighboring galaxies were being pulled off course at over one million miles per hour, towards something we couldn't see.

They called this region the Great Attractor. But their ability to study it was limited.

"The Milky Way has millions and millions of stars and a lot of dust, which is blocking all that information that we could be measuring in that direction. So our own galaxy's blocking the Great Attractor," says Jorge Moreno, a computational astrophysicist at Pomona College. This area we cannot see is known to researchers as the Zone of Avoidance.

Scientists still don't know the full details of what and exactly how the Milky Way and its neighboring galaxies off course, but there have been several candidates over the last few decades.

Most recently, the prime suspect is the supercluster Laniakea, which is Hawaiian for 'immense heaven' or 'immeasurable heaven.'

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Curious about other cosmic mysteries? Email us at shortwave@npr.org.

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Today's episode was produced by Rachel Carlson. It was edited by Rebecca Ramirez. Rebecca, Rachel and Regina checked the facts. Maggie Luthar was the audio engineer.