Chandra image of theVela Pulsar Ordinary matter, or the stuff we and everything around us is made of, consists largely of empty space. Even a rock is mostly empty space. This is because matter is made of atoms. An atom is a cloud of electrons orbiting around a nucleus composed of protonsand neutrons. The nucleus contains more than 99.9 [continue reading]

A new University of Colorado Boulder-led study appears to answer contentious questions about the onset and cause of Earth’s Little Ice Age, a period of cooling temperatures that began after the Middle Ages and lasted into the late 19th century. According to the new study, the Little Ice Age began abruptly between A.D. 1275 and [continue reading]