The solar system contains planets, moons, asteroids, comets, dust and gas that travel around the sun. It includes the planets Mercury, Venus, Earth and Mars, as well as the ice giants Jupiter and Neptune.

Between Mars and Jupiter is a collection of asteroids known as the asteroid belt, while beyond Neptune is where small icy bodies, like comets, live.

How old is our solar system?

The solar system was formed when a giant cloud of dust and gas known as the solar nebula collapsed in on itself. Pieces of space rock that have fallen to Earth have helped scientists figure out the age of the solar system. Some of these small pieces have broken off of moons or planets and can provide interesting scientific information about the chemistry and history of their home body. Others have traveled around the solar system before the planets existed. The oldest known meteorite is the Allende meteorite, which fell to Earth in 1969 and was scattered over Mexico.

How did our solar system form?

The collapse of the solar nebula is thought to have triggered the creation of the solar system. The explosion sent shock waves through space, and those waves pushed parts of the nebula closer together, leading to the collapse. Live Science reported that the material from the supernova may have ended up in the nebula. Live Science sister site reported that scientists have found that aluminum-26, an element formed only in the hearts of stars, most likely came from a series of nearby supernovas.

The sun

An image of a massive solar flare (or coronal mass ejection) erupting out of the sun in 2017.

An image of a massive solar flare (or coronal mass ejection) erupting out of the sun in 2017.  (Image credit: NASA)

According to the University of California, San Diego, the sun is the largest object in the solar system, accounting for almost all of the mass. The energy that sustains life on Earth is provided by the sun, which is powered by nuclear reactions. According to NASA, the yellow dwarf star is made up of gas. Compared with other stars, the sun is small and only one of hundreds of billions of stars in our home galaxy, the Milky Way.

According to NASA, the sun is close to the center of our universe. The stars in the center of the Milky Way are curved. The solar system is located in one of the smaller arms.

The solar system is smaller than the Milky Way. If the solar system was the size of your hand, it would be as big as North America.

Our solar system's planets

There are eight confirmed planets and many dwarf planets on the sun. The order of the planets and other bodies in our solar system is due to the way the solar system formed, according to NASA. NASA says that the materials we are used to seeing as ice, liquid or gas are found in the outer regions of the young solar system.


Mercury transits the sun on Nov. 11, 2019.

Mercury transits the sun on Nov. 11, 2019. (Image credit: NASA/SDO/HMI/AIA)

Mercury is the closest planet to the sun. It is the smallest planet in the solar system, at just over 4,000 miles in diameter, and has no moons. Mercury has no atmosphere to protect it from the sun's relentless radiation, and its surface temperatures can plummet as low as minus 190 F at night. Mercury was named after the Roman messenger of the gods because of its fast rotation around the sun.


A NASA illustration shows the Pioneer-13 probes descending toward the clouds of Venus.

A NASA illustration shows the Pioneer-13 probes descending toward the clouds of Venus. (Image credit: NASA)

Venus is the second planet from the sun and the hottest planet in the solar system. Its atmosphere is a thick layer of mostly carbon dioxide gas that traps heat and allows the planet to reach a sizzling 880 F. Venus is smaller than Earth and has a molten iron core, according to NASA.

phosphine was discovered in the atmosphere of Venus. Some researchers wonder if the clouds of Venus might host life because this chemical is almost always made by living creatures. The findings are controversial and have yet to be fully confirmed, but other work has suggested that it would be difficult for any creatures to survive in such a place because of the lack of liquid water.


This image shows how sunlight fell on Earth during the winter solstice on Dec. 21, 2010.

This image shows how sunlight fell on Earth during the winter solstice on Dec. 21, 2010. (Image credit: NASA)

Earth is the only planet in the universe that is known to harbor life. The presence of liquid water has an effect on its habitability. The ideal distance from the sun to have liquid water is called the Goldilocks zone, and if it were closer, the water would evaporate into a gas. According to the U.S. Geological Survey, about 70% of the planet is covered in water.

Earth is not named after a god. The blue planet is the largest of the four rocky planets in the solar system, and it has one moon. The moon was formed from a piece of Earth that broke off when a giant object smashed into the young planet.


An Illustration of Mars

(Image credit: NASA/JPL-Caltech)

Mars is known as the Red Planet because of the iron-rich dust that covers its surface. The ancient Romans named Mars after their god of war.

The largest volcano in the solar system is located on the fourth planet from the sun, Mars. Without a protective shield, the temperature on Mars is around minus 80 F.

It is likely that liquid water existed on the Martian surface billions of years ago, and some scientists think that Mars still has liquid water today. Mars has two moons: Phobos, which may have formed from ancient rings around the planet, and Deimos, which may have been knocked into its current orbit by an ancient, no-longer-existing moon.


This NASA Hubble Space Telescope image shows auroras above the poles of Jupiter.

This NASA Hubble Space Telescope image shows auroras above the poles of Jupiter. (Image credit: NASA, ESA, and J. Nichols (University of Leicester))

Jupiter is the largest planet in the solar system. Jupiter is a gas giant made up of mostly hydrogen and helium. The king of the Roman gods is known as Zeus in the Greek pantheon.

The fifth planet from the sun, Jupiter, is twice as big as all of the other planets in the solar system combined, yet it has the shortest day of any planet, taking 10 hours to turn about its axis. The rings of Jupiter are made of dust. The largest ocean in the solar system was created by high pressure and high temperatures in the planet's atmosphere.


Saturn, black background

(Image credit: NASA)

The second-largest planet in the solar system is Saturn, the sixth planet from the sun. It is known for its rings. Jupiter is the most dense of the planets and it is composed of hydrogen and helium. Ice particles and rocks make up the rings of Saturn. According to NASA, the planet has dozens of moons, ranging in size from that of a sports field to the size of Mercury. Astronomers say Enceladus is a promising candidate for extraterrestrial life because it is covered in an icy ocean.


The blue body of Uranus glows (pin) with X-rays

(Image credit: NASA/CXO/University College London/W. Dunn et al)

British astronomer William Herschel discovered the seventh planet from the sun using a telescope in 1781. The ice giant is composed of heavier elements than its gas giant neighbors.

Unlike other planets in the solar system, Uranus rolls like a ball as it travels around the sun. The planet appears green-blue due to methane gas in the atmosphere. There are 27 moons on the planet. The only planet named after a Greek deity is Ouranos the sky god.


Neptune, the eighth planet from the sun, was discovered in 1846. Scientists predicted the existence of the planet before it was observed for the first time.

According to Cornell University, it takes 4.15 hours for sunlight to reach Neptune, which is so far from the sun that it is named after the Roman sea god. It takes about eight minutes for the sun to reach Earth. The light that arrives at Neptune is 900 times dimmer than what we see on Earth.

Neptune is made up of water, methane and ammonia. Clouds of methane are propelled at speeds of up to 1,200 mph by strong winds. After going missing for 20 years, one of Neptune's moons was rediscovered.

Why is Pluto not a planet?

NASA’s New Horizons spacecraft took this enhanced color image of Pluto on July 14, 2015.

NASA’s New Horizons spacecraft took this enhanced color image of Pluto on July 14, 2015. (Image credit: NASA/JHUAPL/SwRI)

The ninth planet in the solar system was reclassified as a dwarf planet in 2006 because it failed to meet one of the criteria in the definition of a planet. A planet is defined by the International Astronomical Union as a body that circles the sun and has enough gravity to pull itself into a round or almost-round shape. It is not considered a planet because the neighborhood around it has not been cleared.

Astronomers believe that the reclassification of the ninth planet in the solar system is unfair. A planetary scientist at the University of Central Florida looked at the historical literature and found that the clearing the neighborhood rule appeared in only one paper before the 2006 decision. Live Science previously reported that he and his colleagues concluded that the rule that excludes Pluto from being a planet isarbitrary and not based on historical precedent.

The region beyond Neptune that contains trillions of icy objects is called the Kuiper Belt.

Planet X

An illustration shows what Planet 9 might look like orbiting far from our sun. Now, at least two physicists think this picture is wrong and it's actually a black hole.

An illustration shows what Planet 9 might look like orbiting far from our sun. (Image credit: NASA)

There is a possibility that Planet X or Planet Nine could be the ninth planet. Calculating the distance between the sun and a planet 10 times larger than Earth, California Institute of Technology astronomer Mike Brown and Konstantin Batygin wrote a paper.

Brown said that people who are mad that Pluto is no longer a planet can be happy that there is still a planet out there.

According to NASA, the existence of Planet Nine is still theoretical because the planet has not been directly observed.

Between the planets

There is a large collection of asteroids between Mars and Jupiter. There are over a million known asteroids in the solar system, leftovers from the formation of the solar system, according to NASA.

Asteroids are classified based on their composition.

Beyond the planets

Artist's impression of Kuiper Belt objects.

Artist's impression of Kuiper Belt objects. (Image credit: MARK GARLICK/SCIENCE PHOTO LIBRARY via Getty Images)

The solar system extends to the Oort cloud. According to NASA, the Kuiper Belt is 30 to 55AU wide. The average distance between Earth and the sun is about 93 million miles.

Many of the frozen objects in the region are remnants of the early solar system, according to NASA.

The Oort cloud is a collection of comets that are different from the Kuiper belt because they are located far, far in the solar system.

Additional resources


M. Bartels was born on September 14, 2020. There is a possibility that the phosphine discovered in Venus clouds is a big deal. Here is what you need to know. is a website.

Batygin, K., and Brown, M. There is evidence for a giant planet in the solar system. The journal about astronomy.

M. Bryner was published on November 14. How did Earth get its name? Live science.

C. Choi was born on October 1st. What we know about the Red Planet. is a website.

C. Choi, May 12. Facts about Planet Neptune. is a website.

C. Choi was published on July 10, 2019. The planet that sits on its side is called Uranus. is a website.

October 31 is the date of the report. There are facts about the closest planet to the sun. is a website.

There was a report on January 26. There are facts about the ringed planet. is a website.

C. Choi and C. Gohd were killed on August 16. Venus is a volcanic planet. is a website.

J. Horton was born on November 18. Is there water on Mars? Live science.

The June 30 edition of the journal was written by E. Howell. Fourteen of Neptune's moons have been discovered so far. is a website.

D. Kornreich was published on January 28. How long does it take for the sun's light to reach us? Ask an astronomer at Cornell University.

M. Kramer was published on October 8. Neptune's lost moon was spotted for the first time in 20 years. is a website.

R. Letzer was born on June 4, 2020. New evidence suggests that Mars once had rings and a bigger moon. Live science.

July 22, 2004, NASA How far? How faint?

The space flight center is run by NASA. October 22, 2020. The universe.

NASA science October 30. There is a planet called Jupiter.

NASA science August 30 is the date of the new year. Our solar system is powered by the sun.

NASA Science is a branch of NASA. There are moons of the moon.

NASA science The Kuiper Belt is in depth.

The Night Sky Network is on. In June. What is the difference between the universe and the solar system? The Jet Propulsion Laboratory is part of NASA.

Pultarova, June 30. There is no hope for life in Venus clouds. Live science.

B. Specktor was published on May 6. Scientists think they have found the crash that showered our solar system with gold. Live science.

According to a new study, Earth's moon should be a planet. Live science.

N. T. was born on August 16. Our solar system may have been implanted with the seeds of planets. is a website.

The paper was published on January 17th. How did the moon form? is a website.

The University of California, San Diego. There was a report in 2002. The planets of Jovian origin.

The U.S. Geological Survey. The year ends on November 13 How much water is on the planet?

M Wall was born on February 25. Alien-life hunters are interested in icy ocean moons. is a website.