Terrestrial Planets: Definition & Facts About the Inner Planets By Katharine Gammon Rocky surfaces and molten cores are what the four inner planets of the solar system have in common
How Old Is Earth? By Nola Taylor Redd Scientists have calculated that Earth is 4.54 billion years old, with an error range of 50 million years.
Mars: What We Know About the Red Planet By Charles Q. Choi Learn about planet Mars’ atmosphere, water supply and the possibility to support life, plus, findings from the Mars exploration rover mission.
Ariane 5: European Heavy-Lift Rocket By Elizabeth Howell Ariane 5 is a European heavy-lift rocket that takes satellites and other payloads into Earth orbit.
Deep Impact: The Deep-Space Comet Hunter By Nola Taylor Redd NASA's Deep Impact mission was the most-traveled deep-space comet hunter of its time.
China's Chang'e Program: Missions to the Moon By Adam Mann China's many missions to explore the red moon.
Columbia Disaster: What Happened, What NASA Learned By Elizabeth Howell The space shuttle Columbia broke up on Feb. 1, 2003, killing its seven-member crew. An investigation led to changes in NASA procedures.
Dawn Mission: Shedding Light on Asteroids By Nola Taylor Redd The Dawn spacecraft broke several records when it visited Vesta and Ceres in the asteroid belt.
GRAIL: NASA's Mission to Study the Gravity of the Moon By Nola Taylor Redd Before their fiery demise, NASA's twin GRAIL spacecraft mapped the moon in a quest to learn more about our closest neighbor.
What Is a Blood Moon? By Elizabeth Howell If the rays of the setting or rising sun hit the moon just right, the moon appears to turn red or ruddy-brown. This is called a blood moon.
Deep Space 1: Providing a Wealth of New Space Technology By Nola Taylor Redd The primary mission for NASA's Deep Space 1 was to test out a dozen new advanced technologies. During the spacecraft's ride through space, it also swung by an asteroid and a comet.
Virgin Orbit: The Private Space Company That Aims to Launch Small Satellites By Adam Mann This Virgin Galactic spin-off aims to launch hundreds of small satellites into space at once, aboard their large LauncherOne rocket.
Chelyabinsk Meteor: A Wake-Up Call for Earth By Elizabeth Howell The small asteroid that broke up over the city of Chelyabinsk, Russia, on Feb. 15, 2013, was a reminder about the importance of monitoring small bodies in space that could pose a threat to Earth.
What Are Elliptical Galaxies? By Elizabeth Howell Elliptical galaxies are dim collections of older stars, so they don't shine as brightly as spiral galaxies but they're the most common type of galaxies in the universe.
Virgin Galactic: Richard Branson's Space Tourism Company By Elizabeth Howell Entrepreneur Richard Branson aims to take paying passengers into space in the next few years.
Phoenix Mars Lander: The First Spacecraft to Taste Martian Water By Nola Taylor Redd NASA's Phoenix Mars Lander was a recycled spacecraft that became the first spacecraft to sample water on Mars.
Comet ISON: The Tricky Sungrazing Comet By Elizabeth Howell Comet ISON, discovered by two amateur astronomers in Russia, arrived in Earth's neighborhood in November 2013 and apparently broke up as it rounded the sun.
