Solar System Focus Areas
Studying the planets and other celestial bodies in the space around us.
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 – Mercury, Venus, Earth, 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 – Jupiter, Saturn, Uranus, 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
The Sun
The Sun is the star at the heart of our solar system.
Mercury
Mercury is the closest planet to the Sun and the smallest planet in our solar system.
Venus
Venus, the second planet from the Sun and the sixth largest planet, is the hottest planet in our solar system.
Earth
Earth, the third planet from the Sun and the fifth largest planet, is the only place we know of inhabited by living things.
Mars
Mars, the fourth planet from the Sun and the seventh largest, is the only planet we know of inhabited by robots.
Jupiter
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
Saturn, the sixth planet from the Sun and the second largest in the solar system, is surrounded by beautiful rings.
Uranus
Uranus, the seventh planet from the Sun and the third largest planet in our solar system, appears to spin sideways.
Neptune
Neptune, the eighth and most distant planet from the Sun, is the fourth-largest planet and the first discovered with math.
