Planet Earth: Facts about our home planet Earth is the only planet known to support life. Learn about what Earth is made of and where it came from. The image of Earth in space like a blue marble highlights the planet's fragility and the beauty of Earth (Image credit: NASA) Earth, our home, is the third planet from the sun. While scientists continue to hunt for clues of life beyond Earth, our home planet remains the only place in the universe where we've ever identified living organisms.  Earth is the fifth-largest planet in the solar system. It's smaller than the four gas giants — Jupiter, Saturn, Uranus and Neptune — but larger than the three other rocky planets, Mercury, Mars and Venus. Earth has a diameter of roughly 8,000 miles (13,000 kilometers) and is mostly round because gravity generally pulls matter into a ball. But the spin of our home planet causes it to be squashed at its poles and swollen at the equator, making the true shape of the Earth an "oblate spher...

Saturn: Facts About the Ringed Planet Saturn’s famous rings are spectacular. The most recently discovered ring is at least 200 times the diameter of the planet and could fit one billion Earths. (Image credit: NASA/JPL) Saturn is the sixth planet from the sun and the second-largest planet in the solar system. It's the farthest planet from Earth that's visible to the naked human eye, but the planet's most outstanding features — its rings — are better viewed through a telescope. Although the other gas giants in the solar system — Jupiter, Uranus and Neptune — also have rings, Saturn's rings are particularly prominent, earning it the nickname the "Ringed Planet." Physical characteristics of Saturn Saturn is a gas giant made up mostly of hydrogen and helium. Saturn's volume is greater than 760 Earths, and it is the second most massive planet in the solar system, about 95 times Earth's mass. The Ringed Planet is the least dense of all the planets, and is th...

Jupiter: Our Solar System's Largest Planet Reference Article: Facts about Jupiter, its moons and its famous Giant Red Spot. This new Hubble Space Telescope view of Jupiter, taken on June 27, 2019, reveals the giant planet's trademark Great Red Spot, and a more intense color palette in the clouds swirling in Jupiter's turbulent atmosphere than seen in previous years. Hubble's Wide Field Camera 3 observed Jupiter when the planet was 400 million miles (640 million kilometers) from Earth, when Jupiter was near "opposition," or almost directly opposite the sun in the sky. (Image credit: NASA, ESA, A. Simon (Goddard Space Flight Center) and M.H. Wong (University of California, Berkeley)) Jupiter is the largest planet in the solar system. Fittingly, it was named after the king of the gods in Roman mythology. In a similar manner, the ancient Greeks named the planet after Zeus, the king of the Greek pantheon. Jupiter helped revolutionize the way we saw the universe and...

Venus: The hot, hellish & volcanic planet Facts about the planet Venus. Venus’ atmosphere traps heat from the Sun as an extreme version of the greenhouse effect that warms Earth. The temperature on Venus are hot enough to melt lead. (Image credit: NASA) Venus, the second planet from the sun, is named after the Roman goddess of love and beauty and is the only planet named after a female. Venus may have been named after the most beautiful deity of the pantheon because it shone the brightest among the five planets known to ancient astronomers. In ancient times, Venus was often thought to be two different stars, the evening star and the morning star — that is, the ones that first appeared at sunset and sunrise. In Latin, they were respectively known as Vesper and Lucifer. In Christian times, Lucifer, or "light-bringer," became known as the name of Satan before his fall. However, further observations of Venus in the space age show a very hellish environment. This makes Venus a...

Planet Mercury: Facts about the planet closest to the sun Mercury is the smallest planet in our solar system, known for its short years, long days, extreme temperatures and weird sunsets. A false-color image of Mercury taken by the MESSENGER spacecraft highlights the physical variation across the planet. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington) Mercury is the closest planet to the sun. As such, it circles the sun faster than all the other planets, which is why the Romans named it after their swift-footed messenger god. The Sumerians also knew of Mercury since at least 5,000 years ago. It was often associated with Nabu, the god of writing, according to a site connected to NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) mission. Mercury was also given separate names for its appearance as both a morning star and as an evening star. Greek astronomers knew, however, that the two names refe...

James Webb Space Telescope, the biggest ever built, fully unfolds giant mirror to gaze at the cosmos You can exhale now. The Webb Space Telescope is fully deployed. NASA's James Webb Space Telescope, seen here in an artist's illustration, deployed its final primary mirror segment on Jan. 8, 2022, a critical milestone for its mission to study the universe. (Image credit: NASA) Astronomers and space fans around the world can breathe a sigh of relief: The James Webb Space Telescope is now fully deployed. The $10 billion NASA observatory unfolded the second "wing" of its massive primary mirror today (Jan. 8), bringing the light-collecting structure up to its full size and marking the end of the mission's long, risky and ultra-complex deployment phase.  As the final mirror segment folded in place just before 10:30 a.m. EST (1530 GMT). Just under three hours later, at 1:17 p.m. EST (1817 GMT), the mirror was locked into place as cheers and high-fives erupted at its miss...

Mars: What we know about the Red Planet We're learning more about the fourth rock from the sun every day. Mars as seen from orbit by NASA’s Viking mission. (Image credit: NASA/JPL) Mars is the fourth planet from the sun. Befitting the Red Planet's bloody color, the Romans named it after their god of war. In truth, the Romans copied the ancient Greeks, who also named the planet after their god of war, Ares.  Other civilizations also typically gave the planet names based on its color — for example, the Egyptians named it "Her Desher," meaning "the red one," while ancient Chinese astronomers dubbed it "the fire star." PHYSICAL CHARACTERISTICS The bright rust color Mars is known for is due to iron-rich minerals in its regolith — the loose dust and rock covering its surface. The soil of Earth is a kind of regolith, too, albeit one loaded with organic content. According to NASA, the iron minerals oxidize, or rust, causing the soil to look red. The planet...