Sunday, September 28, 2008

Episode 22 - How do Space Ships Escape the Earth's Gravity and Have We Ever Gone To The Sun?

In this episode I decided to answer three questions at once. Austin from Massachusetts wanted to know how rockets can get away from our gravity. Well it is not done all at once, and it is not done from Earth. Typically space ships get up into orbit about oh 10 000 km up in space. That sounds pretty far, but GPS and communication satellites are about 40 000 km away from our home planet. So, once they get there they start to accelerate (speed up) and until they reach about 7 km/s (that is 25 500 km/h or 15 750 mph, which is pretty fast no matter how you measure it). That is fast enough to win what is really like a tug of war with the Earth's gravity.

Olivia from Washington state wanted to know if space ships had ever been to the Sun. Well of course not manned ships, but there have been a few unmanned ships that have gone. The closest flyby of the Sun was by a ship called Helios 2. She also wanted to know where the Sun came from, how was it created? Well, I touched on this in Episode 18. Basically there was this REALLY big cloud of molecules. Now, even single molecules have gravitational pull, so they started being attracted to on another. After a time (a really long time, about 50 000 000 years) the stuff at the center of this cloud really could be called a star. Oh when did this happen? The Sun is probably about 4.5 billion years old.

I hope you enjoy episode 22.