Hundreds of galaxies hidden behind Milky Way discovered

Scientists have discovered hundreds of galaxies just 250 million light years away from Earth which had been hidden from view until now by our Milky Way galaxy.

The discovery may help to explain the mysterious gravitational anomaly dubbed the Great Attractor, that appears to be drawing the Milky Way and hundreds of thousands of other galaxies towards it with a gravitational force equivalent to a million billion Suns.

Using Commonwealth Scientific and Industrial Research Organisation's (CSIRO) Parkes radio telescope in Australia equipped with an innovative receiver, scientists were able to see through the stars and dust of the Milky Way, into a previously unexplored region of space.

According to Lister Staveley-Smith, professor at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), the team found 883 galaxies, a third of which had never been seen before.

Scientists have been trying to get to the bottom of the mysterious Great Attractor since major deviations from universal expansion were first discovered in the 1970s and 1980s, said Staveley-Smith. "We don't actually



understand what's causing this gravitational acceleration on the Milky Way or where it's coming from," he said.

"We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than two million kilometres per hour," he said.

The research identified several new structures that could help to explain the movement of the Milky Way, including three galaxy concentrations (named NW1, NW2 and NW3) and two new clusters (named CW1 and CW2).

Astronomers have been trying to map the galaxy distribution hidden behind the Milky Way for decades. "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," said Renee Kraan-Korteweg, a professor at University of Cape Town, in South Africa.

"An average galaxy contains 100 billion stars, so finding hundreds of new galaxies hidden behind the Milky Way points to a lot of mass we didn't know about until now," she said.

The study was published in the Astronomical Journal.