What is a Planet? | Planets – NASA Solar System Exploration
Everyone knows that Earth, Mars and Jupiter are planets. But both Pluto and Ceres were once considered planets until new discoveries triggered scientific debate about how to best describe them—a vigorous debate that continues to this day.
In Depth | Our Solar System - NASA Solar System Exploration
Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids.
Planet Compare - NASA Solar System Exploration
2025年1月9日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.
Saturn | Science – NASA Solar System Exploration
2025年1月9日 · As different as Saturn is from Earth, the two planets have some similarities, one of which is the presence of jet streams. Saturn’s most famous and most visible jet stream, however, is far different from those of Earth. It's called the hexagon.
In Depth | Mars – NASA Solar System Exploration
Mars is one of the easiest planets to spot in the night sky – it looks like a bright red point of light. Despite being inhospitable to humans, robotic explorers – like NASA's new Perseverance rover – are serving as pathfinders to eventually get humans to the surface of the Red Planet.
Jupiter By the Numbers – NASA Solar System Exploration
2024年5月7日 · 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.
In Depth | Earth – NASA Solar System Exploration
With a radius of 3,959 miles (6,371 kilometers), Earth is the biggest of the terrestrial planets and the fifth largest planet overall. From an average distance of 93 million miles (150 million kilometers), Earth is exactly one astronomical unit away from the Sun because one astronomical unit (abbreviated as AU), is the distance from the Sun to ...
Mars By the Numbers – NASA Solar System Exploration
2025年1月9日 · Mars is the fourth planet from the Sun, and the seventh largest. It’s the only planet we know of inhabited entirely by robots.
Earth By the Numbers – NASA Solar System Exploration
2025年1月9日 · Your home. Our Mission.And the one planet that NASA studies more than any other.
Pluto By the Numbers – NASA Solar System Exploration
2025年1月9日 · Pluto was once our solar system's ninth planet, but has been reclassified as a dwarf planet. It's located in the Kuiper Belt.