Lyrid meteor shower Meteors or meteorites are bits of rock (like granite) and ice - usually a mixture of rock and iron and nickel but sometimes just rock or just iron - from out in space that get sucked into the gravity of the Earth and fall through our atmosphere to the ground. Usually this is because a comet has passed close enough to the Earth for [...]
Volcano erupting When was the Cretaceous period? During the Cretaceous period, beginning about 145 million years ago, the continents continued to drift away from each other. Plate tectonics Back to the Jurassic Summary of geological eras All our geology articles What happened during the Cretaceous? Because the continents were separated, mammals, birds, and [...]
Diagram of an iron atom When a red giant star finishes changing all of its helium into carbon and oxygen, it then starts to turn the carbon and oxygen atoms into iron atoms. Iron is the heaviest kind of atom that a star can make, so when a star has made most of its carbon and oxygen [...]
