What happens if the sun explodes? When will we first know about it?

The sun might have exploded eight minutes ago. by Brian Delaney, on FlickrThe idea of the sun exploding – going supernova – sure is a frightening one. According to NASA however, it’s not something we should be worried about; it’s just not possible because our sun is too small. I know that fiery ball in the sky seems enormous and amazing to us (and I still think it is), in the grand scheme of the universe, our sun is distinctly average.

Inside the sun, nuclear fusion is taking place – hydrogen atoms are joining together to make helium atoms – creating all the sun’s energy. However, even the hydrogen in the sun (of which there is a lot) is a finite resource and won’t last forever. It is going to last a while – about 5 billion years – but eventually the sun will run out of gas.

When other, larger stars, run out of gas they go ‘bang’ – collapsing in on themselves and spewing out a huge amount of energy in the form of a supernova. These ‘explosions’ are beautiful and extremely bright (sometimes shining brighter than even the galaxies they are in). But in order for a star to do this, it needs to have an incredible amount of mass – at least 8-12 times the size of our sun. So no need to fret – our sun can’t go supernova. And as an added peace-of-mind bonus, no stars within range to damage earth have the mass to go supernova.

So what will happen when our sun does run out of gas?  It will expand out to a red giant, and then ultimately shrink down to a white dwarf star. As a red giant, the outer layer gets larger, but the inside shrinks.

According to researchers who have run theoretical models of our distant future, the Earth won’t be able to escape this expansion and will ultimately be engulfed.  While that may also sound like an unfortunate fate: humanity won’t be around to suffer. A 2012 study predicts that as the sun expands and heats, life on Earth will be uninhabitable for some plants starting in a ‘mere’ 500 million years. Animals and the rest of the plants will all follow suit and kick the bucket in about 1 billion years. Only the hardiest of bacteria will be left in about 2.8 billion years.

And if that isn’t delightfully jolly, then here’s a song and video by NASA to help you understand a little more about the sun.

Question sent from Tim via Facebook

Answer by Autumn Sartain.

 

Other sources:

http://www.nasa.gov/audience/forstudents/k-4/home/F_Supernova.html

http://www.universetoday.com/107791/will-the-sun-explode/

Image Source: Brian Delaney, on Flickr

Article by Autumn Sartain

April 28, 2014

Autumn Sartain’s favourite thing is spending time in nature, which is why she chose to be a wildlife research ecologist. Over the past ten years she has grappled with sea turtles in the tropics, chased song birds in the mountains and sifted through Antarctic seafloor samples. She also somehow managed to carve out the time to gain a postgraduate qualification in Biology. Autumn writes about biology, conservation, and the environmental / outdoor lifestyle – you can find out about her and her writing at autumnsartain.com.


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