Cosmic rays are fast-moving elementary particles, such as protons, electrons and atomic nuclei, that strike the Earth from outer space. They travel almost at the speed of light. Scientists believe they originate from supernovas, black holes and quasars.Know More
The Earth's atmosphere provides protection from cosmic rays. With no atmosphere, these particles would pass through humans and damage their DNA.
Prolonged exposure leads to radiation poisoning and development of medical conditions such as cancer, brain damage and cataracts. During long space missions, like a manned mission to Mars, it is still necessary to find a way to shield travelers from the adverse effects of cosmic rays.Learn More
A comet's tail always points away from the sun because solar wind acts on the nucleus of the comet, and the impacted materials follow the direction of the energy. The tail actually consists of carbon dioxide, or dry ice, changing directly to gaseous form, or melting water, with organic molecules.Full Answer >
Scientists predict that Halley's Comet, also known as Comet Halley, will make an appearance again in late 2061, early 2062. It was last seen in the sky in 1986.Full Answer >
Meteor is the name given to an object as it falls through the Earth's atmosphere. The same object is called a meteoroid when it's outside the atmosphere and a meteorite when it's found intact on the Earth.Full Answer >
The temperature of a comet varies significantly depending on where it is in its orbit around the Sun. Its temperature can range from several degrees above absolute zero to 350 Kelvin or hotter.Full Answer >