Space: The changes happening to the Sun
2 October 2012 Last updated at 18:25 BST
As part of Newsround's space week, Joe's been checking out the biggest object in our solar system, the Sun.
It's around 93 million miles away from Earth, but without it, humans wouldn't be here.
The Sun's going through some big changes at the moment and scientists are trying to understand what's happening to it and how it may affect us in the future.
Joe's been to meet the people in the know...