• Question: What is the biggest star in the Milky Way?

    Asked by @Miannkie to Tim on 13 Mar 2018.
    • Photo: Tim Duckenfield

      Tim Duckenfield answered on 13 Mar 2018:

      Short answer: VY Canis Majoris, a really big red giant about 4000 times the radius of the Sun!

      Trick answer: Sagittarius A*, at the centre. Though it’s not a star, it’s a black hole…

      Long answer: The biggest ‘living’ star by size is Canis Majoris (in the constellation of same name). But it isn’t the biggest object in our galaxy, because when a star is big enough it can collapse into a black hole. We think that most galaxies, including our galaxy the Milky Way, have a SUPERMASSIVE BLACK HOLE in the middle. The galaxy rotates around this black hole in orbit, a bit like a fidget spinner. In the Milky Way, our supermassive black hole is known as SAGITTARIUS A* . It weighs about 4 million times our own Sun – that’s insane! We think it can’t have formed from a single star, but lots of black holes that merged, each of which themselves formed from dying stars.

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