Is the sun at or beginning its RED GIANT stage?

[alxfamlaw]

I have seen this on several sites and wonder if it is true, and if so, what does it mean for us on earth?

[maddog]

Originally Posted by alxfamlaw

I have seen this on several sites and wonder if it is true, and if so, what does it mean for us on earth?

Were this true, we would be in deep trouble. A typical G2 star like this sun in Red Giant phase would extend
out to just past the orbit of Mars. Titan could then become a temprate climate of methane and ammonia.
Actually, recent estimates for the sun is somewhere in the neighborhood of about 3 or more billion years or
so... Of course not all is known of what else can make the sun unstable than running out of fuel (H). If
you can find it there was a show on the Science channel where the actor Neil (I forget?) did a great series
on the future of the sun and planets.

Maddog

[dagaz]

The sun is generally considered to be about halfway through its stage as a Yellow Dwarf, main sequence star, which means we have roughly five billion years until we have to worry about it turning into a Red Giant.

[Tormod]

I think the estimated age of the Sun is about 10 billion years in total. It is now around 4,6 billion years (the same as the Earth). It will eventually start to shine brighter, perhaps as soon as a billion years or two, and thensubsequently start growing, but this is a slow process that will take a very long time. It probably won't become a red giant for another 6 billion years or so, but Earth would be uninhabitable long before that time.

Here is a simple overview which was used for a university lecture:
http://www-astronomy.mps.ohio-state..../vistas97.html

It is outdated now and may be inncorrect, though.

[Evanescence]

There's a great series on Discovery Science called 'Solar Empire' which includes some stuff on the future of the solar system. I recorded some of them, it's a shame that I missed the first few episodes...

Here's some links for you:

• http://www.physlink.com/Education/AskExperts/ae276.cfm
• http://www.chron.com/content/interac...ve/960117.html
• http://news.bbc.co.uk/1/hi/sci/tech/881342.stm
• http://www.obspm.fr/actual/nouvelle/sep04/mira.en.shtml

[maddog]

Originally Posted by Evanescence

There's a great series on Discovery Science called 'Solar Empire' which includes some stuff on the future of the solar system.

I think that was the show I was talking about. It had some neat simulation of what
would happen. The important when to address this thread is > 3 billion as I
said (or 5 billion as Tormod said) years from now. Not that anyone one of us would be
around in either way. No need to worry...

Maddog