What is the magnetosphere?
1 Answer
The magnetic field that surrounds the Earth (or any celestial body).
Explanation:
The Earth is like a big magnet. That is why magnetic compasses work. There are magnetic north and south poles (not located precisely at the true north and south poles). Since the Earth is a big magnet it has a magnetic field. This is a good thing since the Earth's magnetic field works to keep solar wind and cosmic rays from striking the Earth.
Other bodies have magnetospheres (the sun has a really powerful one) but some bodies have almost no magnetosphere at all. Mars has such a weak magnetosphere that any space exploration that occurs there is going to have to find a different way to protect itself from solar wind and cosmic rays. As it stands now, a trip to Mars would be a death sentence for whoever went.