How you can help Brian Cox and Dara O Briain identify supernovae during Stargazing Live

Go online and spot a supernova exploding in a distant galaxy, and help scientists discover how old the universe really is...

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This Friday, a solar eclipse will be the latest astronomical phenomenon to get the nation’s stargazers excited. But to add to the wonderment, viewers can also go online and help spot supernovae, which in turn will help scientists work out how old the universe really is.

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Here’s what you need to know…

What are supernovae?

A supernova is a stellar explosion that briefly outshines an entire galaxy, radiating as much energy as the Sun or any ordinary star is expected to emit over its entire life span, before fading from view over several weeks or months.

How can I help spot them?

You can help identify supernovae by comparing sets of deep space photographs on the Stargazing Live website

Log on to the site, and look at as many pairs of photos as you like – many people last year did hundreds all on their own. Between the tens of thousands of participants who join in, scientists expect to process hundreds of thousands of images several times each.

How will I know when I’ve seen a supernova?

While looking at these images, you’ll be asked to spot bright objects which could be a supernova exploding in a distant galaxy. Scientists will then use the findings to revise the current estimate of the age of the universe. 

Each example will feature two photos of the same patch of sky taken at different times (all in recent months). Look for bright objects that appear in one photo of the pair, but not the other.

That object may be a supernova…

Once scientists have identified candidate supernovae, they carry out some confirmation analysis, and see which type of supernova they might be.

Why do scientists want to find supernovae?

The Stargazing Live scientists are particularly interested in a certain type of supernova (1a), which is known always to explode with identical brightness. The scientists will measure how bright they appear, which tells them how far away they are (The dimmer they appear, the further away they are).

The distance to the supernova, together with its colour, can tell astronomers something that scientists desperately want to know: how old the universe is. Each new supernova gives scientists a slightly different age, and so astronomers combine all estimates to give an average.

They hope to make such a measurement on a new supernova discovered by a viewer, and use it to revise the current estimate of the age of the universe.

Last year, in the Stargazing Live search for Gravitational Lenses, viewers made over 9 million observations.

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A Stargazing Special Friday 20th March, 9:00am BBC1; Stargazing Live Wednesday, Thursday, Friday 8:00pm BBC2