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What is a Planet? | Planets – NASA Solar System Exploration
A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
In Depth | Our Solar System - NASA Solar System Exploration
While our planet is in some ways a mere speck in the vast cosmos, we have a lot of company out there. It seems that we live in a universe packed with planets – a web of countless stars accompanied by families of objects, perhaps some with life of their own.
Planet Compare - NASA Solar System Exploration
Jan 9, 2025 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.
In Depth | Earth – NASA Solar System Exploration
While Earth is only the fifth largest planet in the solar system, it is the only world in our solar system with liquid water on the surface. Just slightly larger than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal.
10 Need-to-Know Things About Saturn - NASA Solar System …
Saturn is the sixth planet from our Sun (a star) and orbits at a distance of about 886 million miles (1.4 billion kilometers) from the Sun.
Overview | Mars - NASA Solar System Exploration
Mars is the fourth planet from the Sun – a dusty, cold, desert world with a very thin atmosphere. Mars is also a dynamic planet with seasons, polar ice caps, canyons, extinct volcanoes, and evidence that it was even more active in the past.
In Depth | Pluto – NASA Solar System Exploration
Dwarf planet Pluto is a member of a group of objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt. This distant realm is populated with thousands of miniature icy worlds, which formed early in the history of our solar system about 4.5 billion years ago.
In Depth | Mars - NASA Solar System Exploration
The fourth planet from the Sun, Mars is one of Earth's two closest planetary neighbors (Venus is the other). Mars is one of the easiest planets to spot in the night sky – it looks like a bright red point of light.
In Depth | Hypothetical Planet X - NASA Solar System Exploration
Jan 20, 2015 · Caltech researchers have found mathematical evidence suggesting there may be a "Planet X" deep in the solar system. This hypothetical Neptune-sized planet orbits our Sun in a highly elongated orbit far beyond Pluto.
In Depth | Venus – NASA Solar System Exploration
It's a cloud-swaddled planet named for a love goddess, often called Earth’s twin. But pull up a bit closer, and Venus turns hellish. Our nearest planetary neighbor, the second planet from the Sun, has a surface hot enough to melt lead.