The solar system consists of eight planets and hundreds of smaller objects like asteroids and moons. They orbit the sun in paths shaped like circles.

The gases in the solar system shoot out a stream of charged particles called the solar wind. This creates a bubble-like region of interplanetary space known as the heliosphere. The edge of the heliosphere is called the heliopause.

The Sun

The Sun is the center of our solar system and, as such, influences the motion of all other bodies in the solar system through its gravitational force. The Sun is a glowing, spinning ball of hot plasma containing primarily hydrogen and helium gas.

The solar energy that powers the sun is primarily produced by nuclear fusion reactions in its core, which converts 600 million tons of hydrogen atoms into 4 million tons of helium atoms every second. This fuel is gradually being withdrawn from the core over time, leading to the formation of a red giant star and the Sun’s eventual death.

The Moon

The Moon is Earth’s natural satellite, orbiting us in a slightly eccentric orbit at a distance of 384,000 km (238,600 miles) from the Sun.

It has a crust, a thick, partially molten layer of minerals called olivine and pyroxene. Its mantle extends from the top of this molten layer to the bottom of its crust, most likely made of magnesium, iron, silicon, and oxygen atoms.

The Moon was subject to violent heating more than four billion years ago, which led to its differentiation and a more dense underlying mantle. This was followed by a second episode of heating from internal radioactivity that resulted in volcanic outpourings of lava.

The Earth

The Solar System consists of 11 planets and a large number of small bodies, including asteroids. It also includes two huge reservoirs of comets: the Oort Cloud and the Kuiper Belt.

Several billion of these objects are believed to be circling the outer edge of the solar system, far beyond the orbits of Saturn and Neptune. They are mainly found in the Oort Cloud and the Kuiper belt, which is about 30 to 50 astronomical units (AU) from the Sun.

From space, Earth appears like a blue marble with white swirls of clouds and areas of brown, yellow, green and white. These colors are based on the color of water, which covers 71 percent of the planet’s surface.

The Planets

The Solar System has eight planets and 210 known planetary satellites (moons).

Astronomers are trying to learn how these planets formed, how they’ve evolved over time and whether there are other Earth-like planets out there. This information is vital to astrobiology, the study of extraterrestrial life.

Using the radial velocity method, astronomers have found two exoplanets that orbit in a close ring around their star. The first is labeled L 98-59b, which has a mass of 1.01 times that of Venus and orbits its star in 2.3 days.

The Asteroids

The Solar System (opens in new tab) is an assemblage of eight planets, more than 210 planetary satellites (moons), many asteroids, comets and other icy bodies, and vast reaches of highly tenuous gas and dust.

Astronomers have learned a lot about the rocky, airless worlds that make up the solar system over the past century. Most of that knowledge has been derived from observations of their orbits and their physical characteristics.

The asteroid belt, the doughnut-shaped ring of asteroids that stretches between the orbits of Mars and Jupiter, has more than a million known asteroids (or minor planets) and probably more. Most of the asteroids are separated on average by a few tens of millions of kilometers. But some mean-motion resonances, rather than dispersing asteroids, cause them to cluster near certain points on their orbits.

The Dwarf Planets

The Solar System is an assemblage of eight planets and more than 210 planetary satellites (moons). There are also many asteroids, comets, and icy bodies in the interplanetary medium.

In 2006, the International Astronomical Union (IAU) decided that a new class of objects should be added to the solar system – dwarf planets. There are currently five known dwarf planets in the Solar System: Ceres, Pluto-Charon, Haumea, Makemake, and Eris.

The Kuiper Belt

The Kuiper Belt is a chilly region of space beyond the gas giant Neptune. It holds trillions of icy bodies that are remnants from the early solar system.

In 1943, Kenneth Edgeworth suggested that comets and other large bodies might exist at this farthest point in the Solar System. In 1951, Gerard Kuiper made an even more detailed proposal.

The Kuiper belt is a disk-shaped region of space that extends from 30 to 55 astronomical units (AU) from the Sun. It is a vast, cold, and dark expanse.