Our galactic neighborhood just got a whole lot more crowded

Researchers have discovered hundreds of nearby galaxies, previously hidden from view by the Milky Way’s own stars and dust. 

Using radio telescopes, the international team of astronomers found 883 galaxies, 240 of which had never been seen before. And at a mere 250 million light-years away, they are close neighbors in astronomical terms.

“The Milky Way is very beautiful of course and it’s very interesting to study our own galaxy but it completely blocks out the view of more distant galaxies behind it,” lead author Lister Staveley-Smith of the International Centre for Radio Astronomy Research (ICRAR) said in a statement.

The discovery was published Tuesday in the Astronomical Journal by a team of scientists from Australia, South Africa, the United States, and the Netherlands. 

“It was not really that surprising, because the stars and dust in our own Milky Way block a not insignificant part of the sky from our view, in optical light that is,” Renee Krann-Korteweg of the University of Cape Town and co-author of the study told Smithsonian. “So yes, we did expect that many galaxies would be lying behind the plane of the Milky Way, or the so-called Zone of Avoidance. However, we did not know anything about their distribution in space.” 

And it’s all thanks to innovative technologies like the Parkes radio telescope, says Bärbel Koribalski from CSIRO Astronomy and Space Science in Australia. Measuring 64-meters, the Parkes telescope is referred to as “the Dish.” Astronomers are able to map the sky 13 times faster than before using this piece of equipment, making new discoveries like this more quickly, Dr. Koribalski explains. 

“We’ve used a range of techniques but only radio observations have really succeeded in allowing us to see through the thickest foreground layer of dust and stars,” Kraan-Korteweg said in a statement. 

This is more than just a cool image, note the authors. Astronomers hope this discovery will help them understand the Great Attractor region, a mysterious gravitational spot in the universe that seems to be drawing in the Milky Way and its neighbors with the force of a million billion Suns.

“We don’t actually understand what’s causing this gravitational acceleration on the Milky Way or where it’s coming from,” explained Staveley-Smith. 

In the 1970s, astronomers realized the Milky Way and its neighbors were speeding toward a blank spot at 14 million miles an hour. Because this is faster than the assumed rate of universe expansion, astronomers concluded that some mysterious gravitational force was acting on this group of galaxies and named the strange dark region the Great Attractor. 

The authors believe the 883 hidden galaxies contribute to the mysterious gravitational force. Each galaxy can contain around 100 billion stars, adding up to a lot of nearby force on the Milky Way. They plan to conduct further follow-up studies to determine if the hidden galaxies’ force is strong enough to finally solve the source of the Great Attractor. 

But some astronomers, such as R. Brent Tully of the University of Hawaii in Honolulu, say the source of the Great Attractor’s force remains a mystery.

“So they did the survey and what they find is, yeah, there are hundreds of galaxies, but there’s nothing really super big back there,” he tells Smithsonian. “So unfortunately it doesn’t really change the big picture all that much or find the answer that we’re looking for, like finding something really outstanding behind the plane might.”

However both skeptics and supporters agree that more research is necessary to completely understand the Great Attractor.