What would happen if the Sun suddenly disappeared from the centre of the Solar System??

Well, the first thing that comes to mind is that we would be plunged into darkness (literally, not figuratively!!). But that won't happen for 8.3 minutes after the Sun has disappeared, since light takes 8.3 minutes to travel from the Sun to the Earth.

Another thing would also happen. We all know that the Earth stays in its orbit mainly due to the gravitational pull exerted by the Sun. So, if the Sun disappears, so will the pull!

Ummm... how long would it be before Earth flies off the tangent and into the big Unknown?! ... Well, that depends on the speed of gravity. So... what is the speed of gravity?!!

Before yesterday, it was generally believed that Gravity travelled at the speed of light. But no one could prove it. Yesterday (7th Jan 2003), two scientists, Ed Fomalont and Sergei Kopeikin announced that they have succeeded in measuring the speed of Gravity for the first time ever. They have established that Gravity does indeed travel at the speed of light. Check it out here.

So, coming back to our problem of the Sun disappearing, we now know that the Earth would remain in orbit for about 8.3 minutes - the time it takes light to travel from the Sun to the Earth. Then, suddenly feeling no gravity, Earth would shoot off into space in a straight line!!

So, keep those space-pods and space-suits ready and be ready to take off in under 8.3 minutes if you hear the news that the Sun has disappeared!! ;-)