How do we know how long the Sun has left to live? | 7 things we need to know

You'll often hear people say that the Sun has about 5 billion years left to live before it runs out of fuel. But where does that number come from? It's quite a simple back of the envelope calculation but there are 7 key things we need to know before we can do that...

For more on why E=mc2 see this article from Ethan Seigel: https://www.forbes.com/sites/startswithabang/2016/05/27/why-does-emc2/
To find out more on helioseismology and how we "listen to the Sun" check out this lecture: https://www.youtube.com/watch?v=wqwGljLDcjM

02:08 - the calculation of the lifetime of the Sun
05:23 - how we know the mass of the Sun
07:54 - how we know the distance between the Earth and the Sun
08:39 - how we measure the brightness of the Sun
09:44 - why E=mc2
11:04 - how we know the Sun is powered by nuclear fusion
13:35 - how we measured the mass difference between 4 Hydrogen atoms and 1 Helium atom
16:58 - how we know the core of the Sun is where nuclear fusion takes place (helioseismology)
19:02 - how we know how old the Solar System (and therefore the Sun) is

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Dr Becky Smethurst is an astrophysicist researching galaxies and supermassive black holes at Christ Church at the University of Oxford.

http://drbecky.uk.com