“We've never seen anything like it” – what’s got astronomers excited?

Astronomers detected an object that displays some very unique properties – but it wasn’t a flying saucer. So, what is it?

Key Points

  • Unique radio signals from the Milky Way baffle scientists.
  • The radio waves fit no currently understood patterns.
  • A new powerful telescope will help solve the mystery within the decade.

Astronomers have discovered unusual signals coming from the centre of our galaxy, the Milky Way. The radio waves fit no currently understood pattern of variable radio source and could suggest a new class of stellar object. 

"The strangest property of this new signal is that…its light oscillates in only one direction, but that direction rotates with time," University of Sydney Astronomist and PhD student Ziteng Wang said. 

"The brightness of the object also varies dramatically, by a factor of 100, and the signal switches on and off apparently at random. We've never seen anything like it."

Radio astronomy is helping us reveal the secrets of the Universe. Pulsars, supernovae, flaring stars, and fast radio bursts are all types of astronomical objects whose brightness varies. 

"At first we thought it could be a pulsar – a very dense type of spinning dead star – or else a type of star that emits huge solar flares. But the signals from this new source don't match what we expect from these types of celestial objects," Mr Wang said. 

Mr Wang and an international team discovered the object using the CSIRO's ASKAP radio telescope in Western Australia. 

They looked towards the centre of the galaxy, and found ASKAP J173608.2-321635, a snappy name referring to its coordinates. This object was unique in that it started out invisible, became bright, faded away and then reappeared. Astronomers described the behaviour as “extraordinary." 

After detecting six radio signals from the source over a nine-month period in 2020, the astronomers tried to find the object in visual light. They found nothing. 

They turned to the Parkes radio telescope and again failed to detect the source, but found it again using a telescope in South Africa.  

The signals have parallels with another emerging class of mysterious objects known as Galactic Centre Radio Transients, including one dubbed the 'cosmic burper'. 

The scientists plan to keep a close eye on the object to look for more clues as to what it might be using a more powerful telescope due to come online within the decade. 

They say the telescope will help solve mysteries such as this latest discovery, but it will also open vast new swathes of the cosmos to exploration in the radio spectrum. 

Watch the video below to see an artist's impression of signals from space.