Reference Pages
24 November 2015, 05:04 PM ET
The full moon happens once a month. Find out when.
01 November 2015, 09:00 AM ET
Find out what's up in your night sky during December 2015 and how to see it in this stargazing guide.
19 October 2015, 01:05 PM ET
The Orionid meteor shower, made up of remnants of Halley's Comet, peaks in mid-October.
07 October 2015, 05:11 PM ET
Mars has water trapped in the polar ice caps. More water may lie just beneath the surface. A new study suggests that water also flows on the surface.
28 September 2015, 09:00 AM ET
Lunar eclipses occur when Earth's shadow blocks the sun. There are three types; the most dramatic is a total lunar eclipse. Find out when is the next one.
18 September 2015, 09:25 AM ET
Total solar eclipses are one of nature’s grandest events. What is a total solar eclipse? How do they work? And when is the next one? We explain.
18 September 2015, 09:00 AM ET
Astronomers use many terms to describe what happens during an eclipse, and this glossary shows some of the more common things they say.
11 September 2015, 08:45 AM ET
Find out the current moon phases. The moon cycles through eight phases every month.
29 August 2015, 12:04 AM ET
Parallax is a method of measuring the distance to nearby objects in space. It is also a method used to display 3D images.
25 August 2015, 07:49 PM ET
The solar system's outer planets — Jupiter, Saturn, Uranus and Neptune — are mainly giant balls of gas much larger than Earth.
20 August 2015, 05:01 PM ET
Astronomers have discovered thousands of extrasolar planets. Researchers hope to find a habitable planet someday.
19 August 2015, 01:21 AM ET
A Lagrange point is a location in space where the interaction between gravitational and orbital forces creates a region of equilibrium where spacecraft can maintain constant orbits.
13 August 2015, 08:30 AM ET
The Perseids meteor shower arises out of the debris of Comet Swift-Tuttle, which last made a pass by Earth in 1992.
13 August 2015, 08:30 AM ET
Watching a meteor shower on a clear, dark night is an unforgettable experience.
12 August 2015, 12:53 AM ET
A super-Earth is an extrasolar planet that is close to Earth's size and mass, but does not have the mass of a gas giant.
10 August 2015, 10:10 PM ET
Rocky surfaces and molten cores are what the four inner planets of the solar system have in common
22 July 2015, 05:20 PM ET
Globular clusters are densely packed, spherical collections of ancient stars. They contain hundreds of thousands, and sometimes millions, of stars.
22 July 2015, 12:00 PM ET
Learn about the discovery of dwarf planet Pluto, its fascinating orbit and atmosphere and the controversy surrounding its planetary status.
22 June 2015, 09:47 PM ET
The Big Bang Theory is the leading explanation about how the universe began.
18 June 2015, 01:11 AM ET
The International Astronomical Union is an organization of professional astronomers and the recognized authority for assigning names to celestial objects.
02 June 2015, 01:59 AM ET
In aviation and in space, a drone refers to an unpiloted aircraft or spacecraft.
02 June 2015, 01:20 AM ET
Edwards Air Force Base is a U.S. military facility where cutting-edge aerospace technologies are tested.
30 May 2015, 04:53 AM ET
North American Aerospace Defense Command (NORAD) is a joint military organization of the United States and Canada that looks for threats in aerospace, patrols the skies for missiles and tracks the whereabouts of Santa Claus.
05 May 2015, 11:02 PM ET
Most of the stars in the universe are main sequence stars. The sun is a main sequence star.
05 May 2015, 11:25 AM ET
The Eta Aquarids are a meteor shower best visible from the Southern Hemisphere.
02 May 2015, 02:51 AM ET
The principles of rockets go back thousands of years, from powering whimsical toys to lifting humans into space.
01 May 2015, 02:14 AM ET
The XS-1 is a space plane under development by the U.S. military's high-tech agency, the Defense Advanced Research Projects Agency (DARPA).
30 April 2015, 12:46 AM ET
DARPA is an agency of the U.S. military that tests and develops new technologies.
24 April 2015, 07:31 PM ET
In a geosynchronous orbit, a satellite orbits Earth at the same speed as the planet is turning, enabling it to stay in place over a single location.
21 April 2015, 02:36 AM ET
The Buran spacecraft was a space shuttle developed by the Soviet Union in response to NASA's space shuttle program. It flew one time.
13 April 2015, 04:53 PM ET
A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe.
10 April 2015, 09:36 PM ET
Albert Einstein determined that massive objects cause a distortion in space-time, which is felt as gravity.