A magnetic field acts like a magnet. Earth's atmosphere and the magnetic field above it block most of the deadly rays from the sun and other stars. Sometimes chunks of rock in space, called meteorites, attracted by Earth's gravity, enter our atmosphere. The atmosphere burns up most meteorites before they can hit Earth. Earth's atmosphere and magnetic field protect life on Earth.
Scientists believe there is probably life somewhere else in the universe.
But they don't know where, yet. With one 24-hour rotation, most of the planet has a night and a day. A planet rotates as if there were a long rod through its center. But there is no rod. We make believe there is and call it an axis.