All hail the Great Attractor: Hundreds of new galaxies emerge

10 Feb 2016

An artist’s impression of the galaxies found in the ‘Zone of Avoidance’ behind the Milky Way, via ICRAR

Hundreds of nearby galaxies have just emerged from a cloak of invisibility, with an odd gravitational anomaly dubbed the Great Attractor finally under the telescope.

A bit of background to start with. The Great Attractor is both wonderfully named and weirdly enthralling, hiding ‘just’ 250 million light years from Earth.

It’s a region that should really have been visible to scientists decades ago, and it’s thought to be sucking the Milky Way and hundreds of thousands of other galaxies towards it with a gravitational force equivalent to a million billion suns.

The problem is that the Milky Way itself has shielded it from our view, until now.

CSIRO to the rescue

Thanks to CSIRO’s Parkes radio telescope (equipped with a new receiver), scientists finally got a peek through the centre, with 883 galaxies – 270 of which are only now discovered – emerging through the cloud.

This anomaly has been quite a mystery ever since it was discovered in the 1970s, with this discovery shedding an awful lot of new light on the subject. Actually, the area is so mysterious that all the newly-discovered galaxies are in what’s called the Zone of Avoidance.

Considering each galaxy has hundreds of millions of stars, that’s quite the new range for astronomers to check out.

Great Attractor galaxiesAn artist’s impression (honestly, this isn’t a photo) showing radio waves travelling from the new galaxies, then passing through the Milky Way and arriving at the Parkes radio telescope on Earth (not to scale), via ICRAR

Prof Lister Staveley-Smith, from the International Centre for Radio Astronomy Research (ICRAR) and lead author on the study, said astronomers have spent decades trying to work out what the Great Attractor is.

“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.”

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).

Gordon Hunt was a journalist with Silicon Republic