Mercury is the closest planet to the Sun and due to its proximity it is not easily seen except during twilight. For every two orbits of the Sun, Mercury completes three rotations about its axis and up until 1965 it was thought that the same side of Mercury constantly faced the Sun. Thirteen times a century Mercury can be observed from the Earth passing across the face of the Sun in an event called a transit, the next will occur on the 9th May 2016.
Mercury Planet Profile
|Mass:||3.30 x 10^23 kg (5.5% Earth)|
|Orbit Distance:||57,909,227 km (0.39 AU)|
|Orbit Period:||88 days|
|Surface Temperature:||-173 to 427°C|
|First Record:||14th century BC|
|Recorded By:||Assyrian astronomers|
- Mercury does not have any moons or rings.
- Your weight on Mercury would be 38% of your weight on Earth.
- A day on the surface of Mercury lasts 176 Earth days.
- A year on Mercury takes 88 Earth days.
- Mercury has a diameter of 4,879 km, making it the smallest planet.
- It’s not known who discovered Mercury.
Venus is the second planet from the Sun and is the second brightest object in the night sky after the Moon. Named after the Roman goddess of love and beauty, Venus is the second largest terrestrial planet and is sometimes referred to as the Earth’s sister planet due the their similar size and mass. The surface of the planet is obscured by an opaque layer of clouds made up of sulphuric acid.
Venus Planet Profile
|Mass:||4.87 x 10^24 kg (81.5% Earth)|
|Orbit Distance:||108,209,475 km (0.73 AU)|
|Orbit Period:||225 days|
|Surface Temperature:||462 °C|
|First Record:||17th century BC|
|Recorded By:||Babylonian astronomers|
- Venus does not have any moons or rings.
- Venus is nearly as big as the Earth with a diameter of 12,104 km.
- Venus is thought to be made up of a central iron core, rocky mantle and silicate crust.
- A day on the surface of Venus (solar day) would appear to take 117 Earth days.
- A year on Venus takes 225 Earth days.
- The surface temperature on Venus can reach 471 °C.
Earth is the third planet from the Sun and is the largest of the terrestrial planets. The Earth is the only planet in our solar system not to be named after a Greek or Roman deity. The Earth was formed approximately 4.54 billion years ago and is the only known planet to support life.
Earth Planet Profile
|Equatorial Diameter:||12,756 km|
|Polar Diameter:||12,714 km|
|Mass:||5.97 x 10^24 kg|
|Moons:||1 (The Moon)|
|Orbit Distance:||149,598,262 km (1 AU)|
|Orbit Period:||365.24 days|
|Surface Temperature:||-88 to 58°C|
- The Earth’s rotation is gradually slowing.
- The Earth was once believed to be the centre of the universe.
- Earth has a powerful magnetic field.
- The Earth is the densest planet in the Solar System.
Mars is the fourth planet from the Sun and is the second smallest planet in the solar system. Named after the Roman god of war, Mars is also often described as the “Red Planet” due to its reddish appearance. Mars is a terrestrial planet with a thin atmosphere composed primarily of carbon dioxide.
Mars Planet Profile
|Equatorial Diameter:||6,792 km|
|Polar Diameter:||6,752 km|
|Mass:||6.42 x 10^23 kg (10.7% Earth)|
|Moons:||2 (Phobos & Deimos)|
|Orbit Distance:||227,943,824 km (1.52 AU)|
|Orbit Period:||687 days (1.9 years)|
|Surface Temperature:||-153 to 20 °C|
|First Record:||2nd millennium BC|
|Recorded By:||Egyptian astronomers|
Facts about Mars
- Mars and Earth have approximately the same landmass.
- Mars is home to the tallest mountain in the solar system.
- Only 18 missions to Mars have been successful.
- Mars has the largest dust storms in the solar system.
- On Mars the Sun appears about half the size as it does on Earth.
- Pieces of Mars have fallen to Earth.
- Mars takes its name from the Roman god of war.
- There are signs of liquid water on Mars.
- One day Mars will have a ring.
The planet Jupiter is the fifth planet out from the Sun, and is two and a half times more massive than all the other planets in the solar system combined. It is made primarily of gases and is therefore known as a “gas giant”.
Jupiter Planet Profile
|Equatorial Diameter:||142,984 km|
|Polar Diameter:||133,709 km|
|Mass:||1.90 × 10^27 kg (318 Earths)|
|Moons:||79 (Io, Europa, Ganymede & Callisto)|
|Orbit Distance:||778,340,821 km (5.20 AU)|
|Orbit Period:||4,333 days (11.9 years)|
|Effective Temperature:||-148 °C|
|First Record:||7th or 8th century BC|
|Recorded By:||Babylonian astronomers|
Facts about Jupiter
- Jupiter is the fourth brightest object in the solar system.
- The ancient Babylonians were the first to record their sightings of Jupiter.
- Jupiter has the shortest day of all the planets.
It turns on its axis once every 9 hours and 55 minutes. The rapid rotation flattens the planet slightly, giving it an oblate shape.
- Jupiter orbits the Sun once every 11.8 Earth years.
- Jupiter has unique cloud features.
The upper atmosphere of Jupiter is divided into cloud belts and zones. They are made primarily of ammonia crystals, sulfur, and mixtures of the two compounds.
- The Great Red Spot is a huge storm on Jupiter.
It has raged for at least 350 years. It is so large that three Earths could fit inside it.
- Jupiter’s interior is made of rock, metal, and hydrogen compounds.
Below Jupiter’s massive atmosphere (which is made primarily of hydrogen), there are layers of compressed hydrogen gas, liquid metallic hydrogen, and a core of ice, rock, and metals.
- Jupiter’s moon Ganymede is the largest moon in the solar system.
Jupiter’s moons are sometimes called the Jovian satellites, the largest of these are Ganymeade, Callisto Io and Europa. Ganymeade measures 5,268 km across, making it larger than the planet Mercury.
- Jupiter has a thin ring system.
- Eight spacecraft have visited Jupiter.
Pioneer 10 and 11, Voyager 1 and 2, Galileo, Cassini, Ulysses, and New Horizons missions. The Juno mission is its way to Jupiter and will arrive in July 2016. Other future missions may focus on the Jovian moons Europa, Ganymede, and Callisto, and their subsurface oceans.
Saturn is the sixth planet from the Sun and the most distant that can be seen with the naked eye. Saturn is the second largest planet and is best known for its fabulous ring system that was first observed in 1610 by the astronomer Galileo Galilei. Like Jupiter, Saturn is a gas giant and is composed of similar gasses including hydrogen, helium and methane.
Saturn Planet Profile
|Equatorial Diameter:||120,536 km|
|Polar Diameter:||108,728 km|
|Mass:||5.68 × 10^26 kg (95 Earths)|
|Moons:||62 (Titan, Enceladus, Iapetus & Rhea)|
|Rings:||30+ (7 Groups)|
|Orbit Distance:||1,426,666,422 km (9.54 AU)|
|Orbit Period:||10,756 days (29.5 years)|
|Effective Temperature:||-178 °C|
|First Record:||8th century BC|
Facts about Saturn
- Saturn can be seen with the naked eye.
- Saturn is the flattest planet.
Its polar diameter is 90% of its equatorial diameter, this is due to its low density and fast rotation. Saturn turns on its axis once every 10 hours and 34 minutes giving it the second-shortest day of any of the solar system’s planets.
- Saturn orbits the Sun once every 29.4 Earth years.
- Saturn’s upper atmosphere is divided into bands of clouds.
The top layers are mostly ammonia ice. Below them, the clouds are largely water ice. Below are layers of cold hydrogen and sulfur ice mixtures.
- Saturn has oval-shaped storms similar to Jupiter’s.
- Saturn is made mostly of hydrogen.
- Saturn has the most extensive rings in the solar system.
The Saturnian rings are made mostly of chunks of ice and small amounts of carbonaceous dust. The rings stretch out more than 120,700 km from the planet, but are are amazingly thin: only about 20 meters thick.
- Saturn has 150 moons and smaller moonlets.
All are frozen worlds. The largest moons are Titan and Rhea. Enceladus appears to have an ocean below its frozen surface.
- Titan is a moon with complex and dense nitrogen-rich atmosphere.
It is composed mostly of water ice and rock. Its frozen surface has lakes of liquid methane and landscapes covered with frozen nitrogen. Planetary scientists consider Titan to be a possible harbour for life, but not Earth-like life.
- Four spacecraft have visited Saturn.
Pioneer 11, Voyager 1 and 2, and the Cassini-Huygens mission have all studied the planet. Cassini orbited Saturn from July 2004 until September 2017, sending back a wealth of data about the planet, its moons, and rings.
Uranus is the seventh planet from the Sun. While being visible to the naked eye, it was not recognized as a planet due to its dimness and slow orbit. Uranus became the first planet discovered with the use of a telescope. Uranus is tipped over on its side with an axial tilt of 98 degrees. It is often described as “rolling around the Sun on its side.”
Uranus Planet Profile
|Equatorial Diameter:||51,118 km|
|Polar Diameter:||49,946 km|
|Mass:||8.68 × 10^25 kg (15 Earths)|
|Moons:||27 (Miranda, Titania, Ariel, Umbriel & Oberon)|
|Orbit Distance:||2,870,658,186 km (19.19 AU)|
|Orbit Period:||30,687 days (84.0 years)|
|Effective Temperature:||-216 °C|
|Discovery Date:||March 13th 1781|
|Discovered By:||William Herschel|
Facts about Uranus
- Uranus was officially discovered by Sir William Herschel in 1781.
- Uranus turns on its axis once every 17 hours, 14 minutes.
- Uranus makes one trip around the Sun every 84 Earth years.
- Uranus is often referred to as an “ice giant” planet.
Like the other gas giants, it has a hydrogen upper layer, which has helium mixed in. Below that is an icy “mantle, which surrounds a rock and ice core. The upper atmosphere is made of water, ammonia and the methane ice crystals that give the planet its pale blue colour.
- Uranus hits the coldest temperatures of any planet.
With minimum atmospheric temperature of -224°C Uranus is nearly coldest planet in the solar system. While Neptune doesn’t get as cold as Uranus it is on average colder. The upper atmosphere of Uranus is covered by a methane haze which hides the storms that take place in the cloud decks.
- Uranus has two sets of very thin dark coloured rings.
The ring particles are small, ranging from a dust-sized particles to small boulders. There are eleven inner rings and two outer rings. They probably formed when one or more of Uranus’s moons were broken up in an impact. The first rings were discovered in 1977 with the two outer rings being discovered in Hubble Space Telescope images between 2003 and 2005.
- Uranus’ moons are named after characters created by William Shakespeare and Alexander Pope.
These include Oberon, Titania and Miranda. All are frozen worlds with dark surfaces. Some are ice and rock mixtures. The most interesting Uranian moon is Miranda; it has ice canyons, terraces, and other strange-looking surface areas.
- Only one spacecraft has flown by Uranus.
In 1986, the Voyager 2 spacecraft swept past the planet at a distance of 81,500 km. It returned the first close-up images of the planet, its moons, and rings.
Neptune is the eighth planet from the Sun making it the most distant in the solar system. This gas giant planet may have formed much closer to the Sun in early solar system history before migrating to its present position.
Neptune Planet Profile
|Equatorial Diameter:||49,528 km|
|Polar Diameter:||48,682 km|
|Mass:||1.02 × 10^26 kg (17 Earths)|
|Orbit Distance:||4,498,396,441 km (30.10 AU)|
|Orbit Period:||60,190 days (164.8 years)|
|Effective Temperature:||-214 °C|
|Discovery Date:||September 23rd 1846|
|Discovered By:||Urbain Le Verrier & Johann Galle|
Facts about Neptune
- Neptune was not known to the ancients.
It is not visible to the naked eye and was first observed in 1846. Its position was determined using mathematical predictions. It was named after the Roman god of the sea.
- Neptune spins on its axis very rapidly.
Its equatorial clouds take 18 hours to make one rotation. This is because Neptune is not solid body.
- Neptune is the smallest of the ice giants.
Despite being smaller than Uranus, Neptune has a greater mass. Below its heavy atmosphere, Uranus is made of layers of hydrogen, helium, and methane gases. They enclose a layer of water, ammonia and methane ice. The inner core of the planet is made of rock.
- The atmosphere of Neptune is made of hydrogen and helium, with some methane.
The methane absorbs red light, which makes the planet appear a lovely blue. High, thin clouds drift in the upper atmosphere.
- Neptune has a very active climate.
Large storms whirl through its upper atmosphere, and high-speed winds track around the planet at up 600 meters per second. One of the largest storms ever seen was recorded in 1989. It was called the Great Dark Spot. It lasted about five years.
- Neptune has a very thin collection of rings.
They are likely made up of ice particles mixed with dust grains and possibly coated with a carbon-based substance.
- Neptune has 14 moons.
The most interesting moon is Triton, a frozen world that is spewing nitrogen ice and dust particles out from below its surface. It was likely captured by the gravitational pull of Neptune. It is probably the coldest world in the solar system.
- Only one spacecraft has flown by Neptune.
In 1989, the Voyager 2 spacecraft swept past the planet. It returned the first close-up images of the Neptune system. The NASA/ESA Hubble Space Telescope has also studied this planet, as have a number of ground-based telescopes.