Re: If the Hubble Telescope faced the sun, could it burn Earth?

Hello Ned,

That is a very interesting question. I've looked at the Hubble Web site, and discovered that the primary mirror of Hubble is about 7 feet in diameter. If you were to aim this mirror at the sun, you could focus the rays in one point. This point would normally be at the imaging camera of Hubble, but it is possible, at least in theory, to focus the rays of the sun at the surface of the Earth, with some minor adjustments. [These minor adjustments would probably mean add considerably more mirrors to Hubble, in order to focus the point of light outside of the body of the telescope itself. Moderator] This is the same thing you would do when you burn paper or ants with a magnifying glass.

This is not dangerous for three reasons. In the first place, the power captured by Hubble's mirror is modest, a few kilowatts, which is the power of a few electric water boilers. A nice blowtorch would be much more effective at putting stuff on fire than hijacking Hubble, modifying it, and aiming it.

This brings me to the second problem. The atmosphere of the Earth is not perfectly still, and this makes it impossible to obtain a nice, tight focus on the Earth. You could get a bit of a bright area, at best.

The third issue is that this area would move very rapidly. Hubble circles around the Earth every 95 minutes, which means the bright spot would move at an astounding 15,800 miles per hour. An individual piece of the planet would be illuminated for such a short amount of time it would never catch fire.

It's a bit strange you think a deranged scientist or astronaut would do such a thing. Weird, deranged scientists, with evil laughs, mostly live in cartoons, not in the real world. Astronauts are very brave people who risk their lives to help mankind by helping scientific progress.

I hope this clears up things for you. You don't have to worry about evil people hijacking Hubble to set the Earth ablaze-it's quite impossible!

Bart Broks