Earthed - How warm will the planets be when Sol is a red giant?

How warm will the planets be when Sol is a red giant?

How warm will the planets be when Sol is a red giant? Everybody knows the sun will swell up and engulf the closer planets (Earth!), but what about the more distant planets? Which ones will survive? Will they be warmer or colder when the sun is a red giant. If warmer, will anyone be about the right temperature for people?

Public Comments

It'll engulf every planet in our solar system.
Not known. Kiss Mercury goodbye, most likely Venus too. Earth will probably be baked to a crisp. It's atmosphere burned off, and its oceans boiled away. Some astrophysicists think the earth may also get swallowed. Mars, at 1.5 AU, will be quite warm.

The moons of Jupiter will warm up a bit. Saturn's moons will probably remain pretty cold, as will the moons of Uranus and Neptune. Diminutive Pluto has 3 moons, and even a red giant sun won't defrost that distant orb. And of course, one can't mention Pluto without discussing Xena, which is bigger than Pluto.

We don't really know how big the sun will get, though we do know it will radiate a lot more heat in its bloated state. It is NOT expected to engulf Mars, and probably won't get quite so big as to absorb earth. The inner planets will be essentially uninhabitable, but the Jovian moons might be far enough away to provide safe haven.

Our best bet, 4 billion years from now, would be to move the earth to a small young red dwarf. Such a star would be safe, stable, and give us plenty of light for many billions of years.
Why worry about it, you will not be around when it does blow up.
hmmm i may be wrong, but i dont think the sun will get any hotter wen it becomes a red giant. all the planets before earth will very likely be engulfed, earth has a pretty good chance too.
All of them will get very hot, even Pluto when the Sun enters it's super giant phase.. The gas giants will for the most part hold onto their atmospheres, but the smaller icy objects will either lose much of their water or be baked dry like comets that make one too many approaches to the sun. The temperature on Mars will be so high it's surface would either glow red hot or even melt, and Jupiter's moons will be left a shrunken shadow of their former selves. Temperatures on Mars would exceed 1,000 degrees Fahrenheit and Jupiter's moons will be hotter than an oven on the broil setting. Titan may however for a brief time be able to maintain liquid water on it's surface before it either loses it or it refreezes. In the end, the outer planets will move away from the Sun as it loses mass and they will survive the Sun's expansion into a red giant then it shedding it's outer layers before collapsing into a white dwarf. However, all of them will not escape without radical changes from the intense heat they experience at the Sun's hands. If any of them experience temperatures humans can live in, it would be at best for a few million years. It would be for the most part either far too hot or much too cold for us.
The sun will lose up to about a third of its mass over its lifetime on the main sequence and in the beginnings of its red giant stage, which will cause all the planets orbits to move outward.

Some scientists think that Mars will be temperate for a while (during the sun's initial expansion into red gianthood).

During the sun's second expansion into an asymptotic giant star, Mars will become a little too warm, and the moons of Jupiter and Saturn may be the next best location (Europa is the best option so far, as it likely has large amounts of water).

But eventually, once the sun has shrunk from red giant to white dwarf, all the planets left in the solar system will end up either ejected from the system (due to their enlarged orbits) or frozen.
Here's an idea to save Earth from an expanding sun, by using asteroids to sling shot the planet to a differant orbit.

http://news.bbc.co.uk/2/hi/science/nature/1154784.stm