Global Warming

Have been reading up a little about the Sun. 

 

The experts currently think it has existed for about 4.6 billion years.  And its size, shape, luminosity, light emission, and other characteristics have been very constant for most of that time.

 

They expect the Sun to last in a burning phase for over 5 billion more years, so it is about halfway through its life as a functioning, normal star. 

 

However, in about 5 billion years, the Sun will likely expand into its red-giant phase, and will engulf Mercury and Venus.  It will come close to engulfing the Earth, or may engulf it, but this won't matter because everything will be fried, all the water and atmosphere stripped away, etc etc.

 

Although it will take a long time for the expanding radius of the Sun to become a problem for Earth, in about 500 million years, the luminosity will be increased, and this is a big problem, because it will cause Earth's temperature to go up enough that all life will be killed, and a lot of the water will be gone.  In other words, the Sun will begin burning progressively brighter (for a young Earth it was not as bright), and therefore the extra photons of light will heat things up on Earth. 

 

So, from a "life" standpoint, the Sun is about 90% already used up, maybe even 95% used up. 

 

This is sortof like when we were kids in school, and they had classes with 55-minute periods.  We would watch the clock, and when 45 minutes of the period was gone, our minds would wander, because there wasn't enough time to get anything useful done anyway.  So that's where we already are - well into that time where nothing will get done.

 

Cool, huh?