13 February 2014, 10:53 AM ET
Ganymede would easily be classified as a planet if were orbiting the sun rather than Jupiter.
12 February 2014, 07:34 PM ET
Edmond Halley is best remembered for predicting the orbit of the comet that was later named after him. Besides astronomy, he also made significant discoveries in the fields of geophysics, mathematics, meteorology and physics.
11 February 2014, 05:00 PM ET
The Gemini program tested docking, rendezvous, spacewalks and long-duration spaceflight in preparation for the moon missions of the late 1960s.
10 February 2014, 06:50 PM ET
Mercury was a NASA program to prove that astronauts could function effectively in space for minutes to hours at a time.
04 February 2014, 03:11 PM ET
NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) launched in September 2013. Here is everything you need to know about it.
31 January 2014, 11:48 PM ET
Gordon Cooper had the longest flight among the original Mercury astronauts.
31 January 2014, 12:46 AM ET
Scott Carpenter, one of the original Mercury astronauts, explored space and later the sea.
30 January 2014, 12:49 AM ET
Deke Slayton was selected for the Mercury program, but had to wait more than a decade to fly in space after concerns about an erratic heartbeat pulled him out of the flight rotation.
29 January 2014, 01:45 AM ET
Wally Schirra, one of the original Mercury Seven astronauts, was the only one who flew in the Mercury, Gemini and Apollo programs.
28 January 2014, 01:46 AM ET
Gus Grissom, one of the original Mercury Seven, also flew on a Gemini mission. He died during training for the first Apollo mission.
27 January 2014, 10:44 PM ET
When stars can't handle their nuclear fuel, they explode in a brilliant burst of light.
22 January 2014, 01:00 PM ET
Ceres is a dwarf planet, the only one located in the inner reaches of the solar system. It is the largest object in the asteroid belt.
15 January 2014, 10:29 PM ET
The density of the universe determines its shape. It could be spherical, saddle-shaped or flat.
06 January 2014, 01:22 PM ET
Kepler-69c, also known as KOI 172.02, is a planet candidate discovered by the Kepler space telescope. It is a "super-Earth" that could hold water on its surface.
02 January 2014, 06:53 PM ET
The rocky planet Kepler-62f could be covered in water, as long as there is enough cloud around the planet to warm the surface below.
31 December 2013, 07:13 PM ET
Kepler-62e is an alien planet that is believed to be in the habitable zone of its red dwarf parent star.
31 December 2013, 06:53 PM ET
Kepler-22b is an alien planet that's a bit larger than Earth, but it's in the habitable region of its star.
30 December 2013, 06:04 PM ET
A do-it-yourself Galilean telescope makes an excellent and inexpensive starter telescope — or science fair project.
24 December 2013, 12:36 AM ET
Based on what we can observe, the universe appears to be almost 28 billion light-years in diameter. However, it is far larger than that.
20 December 2013, 06:21 PM ET
The universe is approximately 13.8 billion years old.
03 December 2013, 06:22 PM ET
Gliese 581g is an extra-solar planet that was discovered in 2010, but quickly cast into doubt by other studies. The original discoverers then published a follow-up paper in 2012 defending their find.
02 December 2013, 01:53 PM ET
A black dwarf is all that is left after a white dwarf star burns off all of its heat, but retains its mass.
02 December 2013, 01:49 PM ET
Brown dwarfs never burn fusion at their core, so scientists sometimes refer to them as "failed stars."
27 November 2013, 11:18 PM ET
Most of the star nearest to Earth are red dwarfs, but they are too dim to be seen with the naked eye.
26 November 2013, 06:11 PM ET
Most stars in the universe will eventually burn off all of their hydrogen and become dead husks called white dwarfs.
25 November 2013, 04:46 PM ET
Shaula, the 24th-brightest star, is a possible multiple-star system in the constellation Scorpius.
22 November 2013, 06:36 PM ET
Gacrux is a variable star that blows strong winds through its system.
21 November 2013, 12:24 AM ET
Beta Crucis is a possible multiple star system in the Southern Cross.
15 November 2013, 05:24 PM ET
NASA's newest Mars probe is expected to study the atmosphere of the Red Planet in amazing new detail.
13 November 2013, 05:10 PM ET
A simple planetarium can be built out of corrugated cardboard.
12 November 2013, 11:55 PM ET
Achernar, the ninth-brightest star, is a binary system, with one of the stars rotating extremely quickly.
11 November 2013, 09:58 PM ET
Rigel Kentaurus (better known as Alpha Centauri) is in the closest star system to Earth and is one of the brightest stars in our sky.