Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...

Nearly 70 years ago, astronomer Paul Merrill was watching the sky through a telescope at Mount Wilson Observatory in Pasadena, California. As he observed the light coming from a distant star, he saw ...

You may have noticed that the rock formations are very different colors. The rock formations on the left are from Red Rock State Park in Texas, and on the right is El Capitan Mountain in Yosemite ...

On the periodic table, most elements have at least one stable form. But others have only unstable forms, all of which decay by emitting radiation and transforming into different elements until ...