2015-04-01 BBC:星光七纪元-21（在线收听）

This is a new source of energy. And this, of course, resists the force of gravity, and in fact, causes the outer atmosphere of the star to expand. The star has begun its dramatic transformation into a red giant. For our own sun, the change will be orangish firing. As in its final years, it turns against the planets in its care. The first thing that happens is it expands out as far as Mercury's orbit here and swallows the Mercury. In this stage it’s about 1000 times more luminous than the sun as it is today. It continues to expand and within another million years also, it gets as far as Venus, and that's end of Venus. Venus is swallowed up. And then the sun continues out towards the earth. If we could see it, we would see something nearly 3000 times brighter than the sun as it is today. It will be 260 times bigger than it is today. But it will not have that beautiful tight compactness of the sun today. Gas will be streaming off the surface. It will be red and turbulent, slightly transparent. It almost seems to become a part of seas. Our only chance of survival would be to flee long before this crisis and go in search for another solar system to call home.