About the Sun
The sun is a star, a hot ball of glowing gases at the heart of our solar system. Its influence extends far beyond the orbits of distant Neptune and Pluto. Without the sun's intense energy and heat, there would be no life on Earth. And though it is special to us, there are billions of stars like our sun scattered across the Milky Way galaxy.
SDO studies the sun's influence by observing the solar atmosphere simultaneously in several wavelengths. The orbiting observatory will help determine if it is possible to make reliable space weather forecasts.
This ultraviolet image of our sun shows bright, glowing arcs of gas flowing around sunspots.
Sun-scorched Mercury is only slightly larger than Earth's moon. Like the moon, Mercury has very little atmosphere to stop impacts, and it is covered with craters. Mercury's dayside is super-heated by the sun, but at night temperatures drop hundreds of degrees below freezing. Ice may even exist in craters. Mercury's egg-shaped orbit takes it around the sun every 88 days.
NASA's MESSENGER is the first spacecraft to orbit Mercury. The spacecraft made three flybys before settling into its primary orbital science mission in March 2011.
The sprawling Caloris basin on Mercury is one of the solar system's largest impact basins.
Venus is a dim world of intense heat and volcanic activity. Similar in structure and size to Earth, Venus' thick, toxic atmosphere traps heat in a runaway 'greenhouse effect.' The scorched world has temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains. Venus spins slowly in the opposite direction of most planets.
About Pioneer Venus 1
Pioneer Venus 1 found Venus to be generally smoother than Earth, though with a mountain higher than Mt. Everest and a chasm deeper than the Grand Canyon.
Scientists used radar to map surface details hidden by Venus' permanent cloud layers.
Earth, our home planet, is the only planet in our solar system known to harbor life - life that is incredibly diverse. All the things we need to survive exist under a thin layer of atmosphere that separates us from the cold, airless void of space.
Earth Science Missions
Orbiting spacecraft study our home world from above as a whole system and aid in our understanding how the planet is changing.
Earth and its moon are nicely framed in this image taken from the Space Shuttle Discovery.
Mars is a cold desert world. It is half the diameter of Earth and has the same amount of dry land. Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons and weather, but its atmosphere is too thin for liquid water to exist for long on the surface. There are signs of ancient floods on Mars, but evidence for water now exists mainly in icy soil and thin clouds.
Opportunity has been roving Mars for 10 years and has returned dramatic evidence that its area of Mars stayed wet for an extended period of time long ago.
Viking proved spacecraft could survive for long periods on Mars -- paving the way for today's rovers
The most massive planet in our solar system -- with dozens of moons and an enormous magnetic field -- Jupiter forms a kind of miniature solar system. It resembles a star in composition, but did not grow big enough to ignite. The planet's swirling cloud stripes are punctuated by massive storms such as the Great Red Spot, which has raged for hundreds of years.
NASA's Juno polar orbiter will study how Jupiter formed and became the dynamic world we see today. Juno will help us better understand the formation of our solar system and other planetary systems.
Humans have watched this giant, raging storm on Jupiter -- the Great Red Spot -- since the 1800s.
Adorned with thousands of beautiful ringlets, Saturn is unique among the planets. All four gas giant planets have rings -- made of chunks of ice and rock -- but none are as spectacular or as complicated as Saturn's. Like the other gas giants, Saturn is mostly a massive ball of hydrogen and helium.
NASA's Cassini orbiter is on an extended mission to explore Saturn and its rings, magnetosphere and moons. Cassini also delivered Europe's Huygens probe to its historic landing on Titan in 2005.
Few sights are more strikingly beautiful than Saturn embraced by the shadows of its stately rings.
Uranus is the only giant planet whose equator is nearly at right angles to its orbit. A collision with an Earth-sized object may explain the unique tilt. Nearly a twin in size to Neptune, Uranus has more methane in its mainly hydrogen and helium atmosphere than Jupiter or Saturn. Methane gives Uranus its blue tint.
About Voyager 2
Most of what we know about Uranus came from Voyager 2's flyby in 1986. The spacecraft discovered 10 additional moons and several rings before heading on to Neptune.
Hubble's near-infrared images show clouds and rings not visible to the unaided eye.
Dark, cold and whipped by supersonic winds, Neptune is the last of the hydrogen and helium gas giants in our solar system. More than 30 times as far from the sun as Earth, the planet takes almost 165 Earth years to orbit our sun. In 2011 Neptune completed its first orbit since its discovery in 1846.
Most of what we know about Neptune is thanks to Voyager 2's 1989 flyby. The spacecraft discovered six of Neptune's moons.
Voyager 2 captured this stunning view of Neptune and its large moon Triton in 1989.
Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. This new class of worlds may offer some of the best evidence about the origins of our solar system.
About New Horizons
NASA's New Horizons will be the first spacecraft to visit Pluto and the Kuiper Belt. The spacecraft's long journey began in January 2006. It will not reach Pluto until 2015.
Pluto and its system of moons are so small they are difficult to see even with powerful telescopes.
Celebrate Earth Day:
NASA Celebrates Earth Day with Public Events, Online Activities
NASA will celebrate the 44th anniversary of Earth Day with a variety of live and online activities 21-27 April. More
MESSENGER Completes Its 3,000th Orbit of Mercury, Sets Mark for Closest Approach
MESSENGER completed its 3,000th orbit and moved closer to the planet than any spacecraft has been before, dropping to an altitude of 199 km. More
News & Events:
NASA Completes LADEE Mission with Planned Impact on Moon's Surface
Ground controllers have confirmed that LADEE has impacted the surface of the moon, as planned, between 9:30 and 10:22 p.m. PDT Thursday, 17 April. More
News & Events:
NASA's Kepler Discovers First Earth-Size Planet In The 'Habitable Zone' of Another Star
"The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth." --Paul Hertz, NASA's Astrophysics Division Director More
News & Events:
NASA Mars Orbiter Spies Rover Near Martian Butte
Curiosity is eyeing a rock layer surrounding the base of a small butte, called "Mount Remarkable," as a target for investigation. More
The Scale of Discovery - 26 Apr 2014
The fourth annual multi-site professional development workshop delves into the stories behind NASA missions, from conception to science results. More
Art and the Cosmic Connection
An interdisciplinary program to encourage learners to explore the mysterious worlds in our solar system and their geologic stories. More
What's Up in April
Mars at opposition, a lunar eclipse and April's Lyrid meteor shower. More
Solar System 101:
Homework? We Can Help
We can't give you the answers to your science homework, but our Homework Helper can show you where to look and how to impress your teacher. More