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Solar System Focus Areas

Studying the planets and other celestial bodies in the space around us.

An overhead illustration of our solar system shows the Sun as a bright dot in the center of the black background of space, surrounded by a half-dozen elliptical orbits. A green ellipse represents Earth's orbit. A blue one closely circles around that, while an orange one crosses the green orbit in two places.

NASA’s Planetary Science Division brings a variety of scientific disciplines – including geology, chemistry, astronomy, physics, and biology – to the study of planets and small bodies in our solar system.

NASA missions have visited every planet in our solar system, as well as asteroids, comets, and other small bodies, returning observations, data – and sometimes samples – that help us to understand how the solar system was formed, how it has evolved, and whether there are any signs of habitability on other worlds within it.

One way to study our solar system is to break it down into the planets of the inner and outer solar system, and the small bodies that orbit within.

The inner solar system planets – MercuryVenusEarth, and Mars – are rocky and are thought to have formed from the accumulation of dust into small planetesimals, then into larger protoplanets, and then into the planets, though their evolutions likely differed.

Outer solar system planets – JupiterSaturnUranus, and Neptune – are known as gas giants. Jupiter and Saturn consist mostly of hydrogen and helium, while Uranus and Neptune are mostly water, methane, and ammonia.

The small bodies of our solar system include comets, asteroids, and meteors, as well as objects in the Kuiper Belt and Oort Cloud, and dwarf planets.

At NASA, the Planetary Science Division is charged with exploration of the solar system, except for the Sun and Earth, which are studied by NASA’s Heliophysics Division and Earth Science Division, respectively.

Our Solar system

Extreme ultraviolet image of the Sun showing the bright flash of a solar flare on the left side

The Sun is the star at the heart of our solar system.

A full globe view of gray-colored planet Mercury as seen from a spacecraft. Craters and white patches also are visible.

Mercury is the closest planet to the Sun and the smallest planet in our solar system.

A serene-looking Venus with creamy white, and tan clouds.

Venus, the second planet from the Sun and the sixth largest planet, is the hottest planet in our solar system.

Our blue marble home world as seen from a distant satellite.

Earth, the third planet from the Sun and the fifth largest planet, is the only place we know of inhabited by living things.

Image: Mars on Dec. 3, 2007; longitude ~320 degrees

Mars, the fourth planet from the Sun and the seventh largest, is the only planet we know of inhabited by robots.

cracked ice in bright color

Jupiter is the fifth planet from the Sun and the largest in the solar system – more than twice as massive as the other planets combined.

Saturn has subtle shades of yellow, brown, and red in this image from a spacecraft. The planet is encircled by its famous ring system.

Saturn, the sixth planet from the Sun and the second largest in the solar system, is surrounded by beautiful rings.

Pale blue planet Uranus is seen against the darkness of space in an image from the Voyager 2 spacecraft.

Uranus, the seventh planet from the Sun and the third largest planet in our solar system, appears to spin sideways.

Dark spot on Neptune

Neptune, the eighth and most distant planet from the Sun, is the fourth-largest planet and the first discovered with math.