Will the sun become a red giant and swallow the earth?
Yes. As mentioned previously, the sun will expand during it’s red giant phase. In doing so it will swallow up Mercury and Venus, Earth was assumed to be safe since the radius of the Sun would still be less than that of Earth’s orbit. However, Earth would not orbit the same… think of a satellite – it orbits the earth at some speed high above the atmosphere quite happily. If that same satellite were placed in the atmosphere it would lose speed through friction and eventually crash land. If you want to think about it another way, an airplane cruising at high altitude is a lot safer than one flying 10 foot off the ground.
