Interesting Solar System Facts

solar system facts

Our Solar System comprises the Sun and all the celestial bodies that are held in its gravitational pull. The most significant of these are the planets, the eight largest known objects in the Solar System. The planets have occupied a central place in Mankind’s culture for thousands of years. Each of the planets has its own fascinating characteristics and history. We have dozens of awesome solar system facts below, check them out!


Mercury is the closest planet to the Sun, and one of the four rocky terrestrial planets in the Solar System. Less is known about Mercury than any of the other planets, due to the difficulties in observing the planet from Earth. Mercury’s exterior closely resembles our Moon, but Mercury has an iron core.

-Mercury is now officially the smallest planet in the Solar System.

-The moons Ganymede and Titan are bigger than Mercury.

-Mercury has the most eccentric orbit of all the planets.

-Mercury’s orbit could not be explained by scientists till Albert Einstein formulated the General Theory Of Relativity in the early 20th century.

-Apart from during solar eclipses, Mercury can only be seen from earth in the morning and evening twilight due to the glare of the sun.

A Guide to Mercury: An overview of Mercury and its characteristics and geology.

Mercury Unveiled: An in-depth article on Mercury with photographs of the planet.

MESSENGER and Mercury: The home for the space probe circling Mercury, with in-depth information and stunning pictures of the planet’s surface.


Venus, named after the Roman goddess of love, is the second closest planet to the sun in the Solar System. Highly visible in the night sky, Venus was once suspected of having similar surface conditions to Earth, but in fact she has a highly pressurized atmosphere mainly consisting of carbon dioxide and clouds of acid.

-After the Moon, Venus is the brightest object in the night sky. It is so bright that it can cast shadows on Earth.

-Venus is sometimes referred to as Earth’s “sister”, due to the two planets similarity in size, composition and gravity.

-Venus has the densest atmosphere of the four terrestrial planets.

-The surface of Venus is obscured by clouds made of sulfuric acid.

-Venus may have once possessed oceans like the earth, but these have evaporated as the planet has got hotter.

The Planet Venus: An overview of historical and present scientific views of Venus, with photographs.

Venus Crater Database: A guide to the surface of the planet.

The Rarest Eclipse: Information on the rare event of Venus transiting across the face of the Sun.


The largest of the terrestrial planets, Earth is the home to countless billions of lifeforms, protected by a unique atmosphere created by interactions between the planet’s biosphere, its magnetic field and its solitary moon. By pure chance, Earth occupies the perfect celestial location to allow life to form, develop and observe the rest of the universe.

-Earth is the densest planet in the solar system.

-Earth remains the only location where life is known to exist in the universe.

-Earth’s surface is composed of tectonic plates that slowly move across the surface over millions of years.

-Earth is the only planetary body known to possess liquid water.

-Barring massive environmental changes, Earth could continue to support life for up to another two billion years before the Sun’s expansion will blow the planet’s atmosphere away.

Earth from Space: The Smithsonian Institution’s online exhibition with stunning images of the planet and its surface.

Profile of the Earth: Information about the planet with color photographs of each of the continents and oceans.

Images of the Earth: A resource for imagery of not only the Earth itself, but the magnetic fields surrounding the planet.


Mars, the fourth planet in the Solar System, remains popular in the public imagination due to recent scientific discoveries that suggest that the planet once harbored life. Mars’ similarities to Earth in its geological features and seasonal cycles indicate the two planets may have once been very similar. However, Mars is now a geologically dead world.

-Mars is known as the “Red Planet” due to the high prevalence of iron oxide on its surface.

-Mars is home to the highest known mountain and the largest known canyon in the Solar System.

-Mars can be seen with the naked eye from the Earth.

-Unmanned missions to Mars have discovered geological evidence that it may once have possessed liquid water, an essential ingredient for life to develop.

-The orbit of Mars sometimes brings it as close as 55 million miles from Earth.

Phoenix Mars Mission: The home of the unmanned probe on Mars, with articles, education materials and photographic galleries of the planet.

Mars Exploration Rovers: A website for the two unmanned rovers on Mars’ surface, Spirit and Opportunity with numerous photos taken by the vehicles.

Mars Resources: A collection of articles an links about Mars.


Jupiter is the closest of the gas giant planets orbiting the Sun. Jupiter is the third brightest object in the Earth’s night sky, behind the Moon and Venus. Jupiter is primarily made of hydrogen, but may possess a core of heavy elements. The planet possesses a powerful magnetic field and a vast collection of orbiting satellites.

-Jupiter is the largest planet in the Solar System.

-Jupiter’s mass is two and a half times that of all the other planets in the Solar System put together.

-Jupiter’s rapid rotation means that the planet noticeably bulges around the equator.

-Jupiter’s atmosphere contains a gigantic storm known as the “Great Red Spot” that is known to have been raging since at least the 17th century.

-The planet is orbited by at least 63 moons, the largest off which, Ganymede, is bigger than Mercury.

Images of Jupiter: The Chandra X-Ray Observatory supplies some stunning imagery of the gas giant.

Jupiter’s Second Red Spot: An article with photographs chronicling the discovery of a second huge storm in Jupiter’s atmosphere.

Pictures of Jupiter and its Satellites: A large collection of images to download of the largest planet in the Solar System.


Saturn’s distinctive system of rings make it one of the most instantly recognizable images in the world. Like its neighbor Jupiter, Saturn is primarily composed of hydrogen gas with a tiny core of ice and rock at its heart. Saturn is the furthest of the planets that can be regularly perceived with the naked eye from Earth.

-Saturn is the only planet in the Solar System with a density lower than water.

-Saturn’s atmosphere has wind speeds of up to 1,800 km/h, even faster than the winds on Jupiter.

-Saturn’s famous rings primarily consist of ice particles with some dust and rocky debris.

-With 61 moons, Saturn is second only to Jupiter in its number of satellites.

-Saturn’s moon Titan is the only moon in the solar system that is known to possess a significant atmosphere of its own.

Saturn at the Galileo Project: An informative article on the planet and the history of its observations from Earth.

CICLOPS: The home on the Web for information and imagery from the Cassini orbiting spacecraft as it observes Saturn and its satellite system.


Uranus is the third largest of the planets in the Solar System, and differs from Jupiter and Saturn in possessing significant quantities of ice in its atmosphere, cont5ributing to the incredible cold of the planet. Although Uranus possesses a complex layered atmosphere, from the exterior the planet appears to be completely featureless.

-Uranus’ discovery was in 1781 was the first expansion to the boundary of the Solar System in the modern historical period.

-Uranus was the first planet to be discovered with a telescope. It has since been found that Uranus can occasionally be observed with the naked eye from Earth.

-Uranus has the coldest atmosphere of any planet in the Solar System. The minimum temperature of the planet is -224 degrees Celsius.

-Uranus is unique in that it rotates on its side. Its poles are where other planets have their equators.

-Due to its rotation, Uranus’s moons appear to circle it like the hands of a clock.

Information on Uranus: An overview of Uranus and her satellites.

Uranus Image Gallery: A collection of photographs of the planet and her moons taken from unmanned space probes.

A Guide to Uranus: A resource for information on Uranus, its characteristics and history of observation.


-Neptune was the first planet to be discovered due to prediction rather than observation, after anomalies in Uranus’ orbit led astronomer Alexis Bouvard to suspect another planetary body was influencing it.

-Neptune’s deep blue appearance is due to the presence of methane in its outer atmosphere.

-Neptune has the highest ever recorded wind speed in the Solar System, reaching 2,100 km/h.

-Neptune has a “Great Dark Spot” in its southern hemisphere, similar to the “Great Red Spot” observable on Jupiter.

-While the top of Neptune’s clouds can be as cold as -218 degrees Celsius, its center reaches over 5,000 degrees.

Planet Neptune Data: A comprehensive set of statistics and facts about Neptune.

Facts about Neptune: A resource about the most distant observed planet.


Pluto held the title of the Solar System’s ninth planet from its discovery in 1930 until 2006. It is now considered one of the largest members of the Kuiper Asteroid Belt. Pluto has always held an affectionate place in popular culture, and there was a significant public backlash to the decision to change its planetary status.

-Pluto’s status as a planet was stripped in 2006 after observation of a larger body, Eris, in the Kuiper Asteroid Belt. Some scientists continue to dispute this decision.

-It has now been reclassified in a new category as a dwarf planet.

-Pluto’s highly eccentric orbit means that it sometimes closer to the Sun than Neptune.

-Pluto and its moon Charon may actually form a binary system, orbiting around a point in-between the two bodies.

-Pluto’s two other moons Nix and Hydra were only discovered by the Hubble Space Telescope in 2005.

Fast Facts about Pluto: An overview of known information on the former ninth planet.

What do we know about Pluto?: An article examining the paucity of information astronomers possess about the distant dwarf planet.