Our Solar System

Explore the planets, moons, and other celestial bodies that make up our cosmic neighborhood.

General Overview

Our solar system formed about 4.6 billion years ago from a dense cloud of interstellar gas and dust. The Sun contains 99.8% of the mass in our solar system, with the remaining 0.2% contained in the planets, moons, asteroids, comets, and other objects.

The solar system consists of the Sun, eight planets, five officially recognized dwarf planets, at least 218 moons, and countless smaller objects like asteroids and comets. The four inner planets (Mercury, Venus, Earth, and Mars) are rocky terrestrial worlds, while the four outer planets (Jupiter, Saturn, Uranus, and Neptune) are gas giants.

Beyond Neptune lies the Kuiper Belt, a region of icy bodies including the dwarf planet Pluto. Even further out is the Oort Cloud, a theoretical cloud of predominantly icy objects that may extend up to 100,000 astronomical units from the Sun.

Planet Profiles

Learn about the unique characteristics of each planet in our solar system.

Mercury

Type: Terrestrial

Diameter: 4,880 km

Distance from Sun: 57.9 million km

Day Length: 58.6 Earth days

Year Length: 88 Earth days

Notable Features: Smallest planet, extreme temperature variations, heavily cratered surface

Venus

Type: Terrestrial

Diameter: 12,104 km

Distance from Sun: 108.2 million km

Day Length: 243 Earth days

Year Length: 225 Earth days

Notable Features: Hottest planet, thick atmosphere, retrograde rotation

Earth

Type: Terrestrial

Diameter: 12,756 km

Distance from Sun: 149.6 million km

Day Length: 24 hours

Year Length: 365.25 days

Notable Features: Only known planet with life, 71% water coverage, active geology

Mars

Type: Terrestrial

Diameter: 6,792 km

Distance from Sun: 227.9 million km

Day Length: 24.6 hours

Year Length: 687 Earth days

Notable Features: Red planet, polar ice caps, largest volcano in the solar system

Jupiter

Type: Gas Giant

Diameter: 142,984 km

Distance from Sun: 778.6 million km

Day Length: 9.9 hours

Year Length: 11.9 Earth years

Notable Features: Largest planet, Great Red Spot, at least 79 moons

Saturn

Type: Gas Giant

Diameter: 120,536 km

Distance from Sun: 1.4 billion km

Day Length: 10.7 hours

Year Length: 29.5 Earth years

Notable Features: Spectacular ring system, at least 82 moons

Uranus

Type: Ice Giant

Diameter: 51,118 km

Distance from Sun: 2.9 billion km

Day Length: 17.2 hours

Year Length: 84 Earth years

Notable Features: Rotates on its side, faint ring system, 27 known moons

Neptune

Type: Ice Giant

Diameter: 49,528 km

Distance from Sun: 4.5 billion km

Day Length: 16.1 hours

Year Length: 165 Earth years

Notable Features: Windiest planet, Great Dark Spot, 14 known moons

Beyond Planets

The Sun

At the center of our solar system is the Sun, a G-type main-sequence star that contains 99.8% of the system's mass. The Sun is a nearly perfect sphere of hot plasma with a diameter of about 1.39 million kilometers, about 109 times that of Earth. Its core reaches temperatures of 15 million degrees Celsius, where nuclear fusion converts hydrogen into helium, releasing enormous amounts of energy.

The Sun's energy output in the form of light and heat makes life possible on Earth and influences every planet in the solar system. Its magnetic field extends far beyond Pluto, creating a bubble in interstellar space called the heliosphere.

Asteroid Belt

Between the orbits of Mars and Jupiter lies the asteroid belt, a region populated by millions of rocky objects. These range in size from dust particles to the dwarf planet Ceres, which has a diameter of about 940 kilometers. The total mass of the asteroid belt is only about 4% that of Earth's moon.

Scientists believe the asteroid belt is made up of material that never formed into a planet due to Jupiter's strong gravitational influence. Many meteorites that strike Earth originate from the asteroid belt.

Kuiper Belt

Beyond Neptune's orbit lies the Kuiper Belt, a region extending from about 30 to 50 astronomical units from the Sun. This disc-shaped region is populated by icy bodies, including dwarf planets like Pluto, Haumea, and Makemake. The Kuiper Belt is thought to contain hundreds of thousands of icy bodies larger than 100 km across and an estimated trillion or more comets.

Oort Cloud

The outermost region of our solar system is the Oort Cloud, a theoretical cloud of predominantly icy objects that may extend from 2,000 to 100,000 astronomical units from the Sun. This region is thought to be the source of long-period comets that can take thousands of years to orbit the Sun. The Oort Cloud marks the boundary of the Sun's gravitational influence, where objects are loosely bound to the Sun and can be affected by the gravitational pull of passing stars.