Astronomers have been confounded by recent evidence that the universe expanded at different rates throughout its life. New ...

Scientists think these objects accelerate cosmic ray particles to high energies and send them out zooming through the Universe. When they slam into Earth's atmosphere, they are, briefly ...

According to a tenet scientists call the cosmological principle, our place in space is in no way exceptional. But recent ...

The atmosphere, a thin veil of molecules enveloping Earth, reaches about 20 miles (32 kilometers) above the planet's surface.