sciencetech-blog

comments

Scientists say they now have firm evidence that our solar system is contained inside a large 'bubble'.

They say that 10 million years ago a nearby cluster of supernovas went off like 'popcorn' and blew an enormous bubble in the interstellar medium that we now inhabit.

Called the 'Local Bubble', this peanut-shaped area 300 light-years across reveals why there is very little of the dust and gas seen elsewhere in the universe in our vicinity.

Scroll down for video explanation 

Researchers at the University of Miami say they have found evidence that our solar system is inside a 'bubble' (diagram shown) where there is no dust and gas seen elsewhere in the interstellar medium. The Local Bubble theory suggests that this material was blasted away be supernovas millions of years ago

The Local Bubble was first postulated in the 1970s and 1980s, but the existence of it had been contested.

At the time, when astronomers looked around our solar system, they found an odd lack of gas and dust seen in the interstellar medium elsewhere in the universe

Meanwhile, astronomers had begun detecting an abundance of X-ray radiation around Earth.

This suggested that our solar system was mostly empty because radiation from supernovas had blasted away our interstellar medium.

While these supernovas were not enough to exterminate life on Earth, they were close enough to wrap our solar system in a bubble of hot gas that persists today. 

Contesting the theory, however, some scientists said that the X-rays could be accounted for by the sun.

They claimed that something known as 'charge exchange' could be to blame, which involves solar wind causing X-ray radiation by 'stealing' electrons from neutral gas in space.

To see which theory was true, researchers from the University of Miami launched a sounding rocket, one that flies into space on a short trip and back, from White Sands Missile Range in New Mexico in December 2012.

The rocket reached a peak altitude of 160 miles (260 km) and spent five minutes above the atmosphere, carrying with it an x-ray detector called the Diffuse x-ray emission from the Local Galaxy (DXL).

During the flight, DXL found that 40 per cent of soft x-rays detected originated in the solar system.

The rest, researchers surmised in their paper in the journal Nature, must come from a Local Bubble of hot gas left over from supernovas explosions.

'This is a significant discovery,' said Professor Massimiliano Galeazzi, who led the research.

'[It] affects our understanding of the area of the galaxy close to the sun, and can, therefore, be used as a foundation for future models of the galaxy structure.'

Galeazzi and collaborators are already planning the next flight of DXL, which will include additional instruments to better characterise the emission. The launch is currently planned for December 2015.

Evidence suggests that many supernovas exploded like 'popcorn' near our solar system millions of years ago, leaving their radiation behind as a signature of their action. In this image a supernova remnant lies in the Large Magellanic Cloud (LMC), a small galaxy about 170,000 light-years from Earth