The Solar System

Our tiny corner of Universe is dominated by a star we call the Sun. Trapped in the gravity of the Sun is a huge family of bodies – planets, moons, asteroids, comets which hurtle with it through space. This family is our Solar System. The effects of the Sun, its heat, gravity and light extend far beyond the farthest planet, Pluto, to about a quarter of the way to the next nearest star, Proxima Centauri.

The Planets Nine planets orbit the Sun at different distances. The four inner planets (Mercury, Venus, Earth and Mars) are balls of rock and metal. The outer planets (Jupiter, Saturn, Uranus and Neptune) are giant balls of gas and liquid. Pluto, the furthest planet is made from ice and rock. The time it takes a planet to orbit the Sun is its orbital period (its year). Planets also rotate as they travel. The time it takes for a planet to rotate once is its rotation period (its day).

The Sun Size: Diameter of 1,390,000 km Mass: 1.99 x kg Distance from Earth: million km Composition:70% Hydrogen, 28% Helium, 2% other elements Temperature:Surface: 5,800 o C Core: 15,600,000 o C Planets:9 Colour:Orange

The Sun is a 1.4 million km ball of burning gas. Variations in the Sun’s magnetic field cause huge solar flares to shoot into space. Solar flares can be accompanied by dense clouds of electrically charged solar wind. Solar wind can disrupt communication satellites. The Sun

Mercury Size: Diameter of 4,880 km Mass: 3.30 x kg Distance from Sun:57.91 million km Distance from Earth: Max million km Min 92 million km Atmosphere:Negligible atmosphere Temperature: 450 o C Day; -170 o C Night Length of Year: 88 Earth days Length of Day: 59 Earth days Moons: None Colour:Dark Grey Core: Iron rich core about 3600 km in diameter

The most conspicuous feature on the planet is the huge Caloris Basin (1300 km across). The Caloris Basin was formed by a collision between Mercury and another rocky body. Mercury has the widest temperature range on any planet in the Solar System. Mercury

Venus Size: Diameter of 12,104 km Mass: 4.87 x kg Distance from Sun: million km Distance from Earth: Max 258 million km Min 41 million km Atmosphere:Mainly carbon dioxide 90 times Earth pressure Temperature: Average 480 o C Length of Year: 225 Earth days Length of Day: 243 Earth days Moons: None Colour:White cloud tops Core: Iron/Nickel core

Venus has the longest day of any planet in the Solar System (243 days). It’s the only planet where the sun rises in the west and sets in the east. Venus has a poisonous atmosphere – it is full of sulphuric acid. It’s thick carbon dioxide atmosphere creates a strong greenhouse effect. Venus

Earth Size: Diameter of 12,756 km Mass: 5.97 x kg Distance from Sun:149.6 million km Atmosphere:Mainly nitrogen with oxygen and carbon dioxide Temperature: Average 22 o C Length of Year: Earth days Length of Day: 24 Earth hours Moons: 1 (The Moon) Colour:Blue and green Core: Iron/Nickel core

The only planet in the Solar System where life has been confirmed. The planet is the correct distance from the Sun for water to exist as a liquid. Earth’s oceans help regulate the planet’s temperature. The Earth’s atmosphere and magnetic field shield the planet from most of the solar radiation. Earth

Mars Size: Diameter of 6,792 km Mass: 6.42 x kg Distance from Sun:228 million km Distance from Earth: Max 378 million km Min 78 million km Atmosphere:Thin carbon dioxide atmosphere Temperature: Average -55 o C Length of Year: 687 Earth days Length of Day: 24 Earth hours 37 minutes Moons: 2 (Deimos and Phobos) Colour:Red Core: Small iron core

The temperature of Mars is closer to Earth than any other planet in the Solar System (27 o C in summer). Valles Marineres is the longest ever canyon system. It measures over 5,000 km along the equator with an average depth of 6 km. Olympus Mons is the largest volcano in the Solar System. It measures 700 km wide and reaches 27 km high. Mars

Jupiter Size: Diameter of 142,984 km Mass: 1.90 x kg Distance from Sun:778.3 million km Distance from Earth: Max 928 million km Min 628 million km Atmosphere:Mainly hydrogen and helium Temperature: -123 o C at the surface 20,000 o C at the core Length of Year: 4,333 Earth days Length of Day: 10 Earth hours 40 minutes Moons: 58+ (Io, Europa, Ganymede and Callisto) Colour:Yellow/orange Core: Rocky iron core

Jupiter is one of the four ‘gas giant’ planets. It is composed of a swirling ball of gas with a small rocky core. The Great Red Spot is a vast thunderstorm that has raged on Jupiter for over 400 years. The Great Red Spot is over twice the size of Earth and is the largest thunderstorm in the Solar System. Jupiter

Size: Diameter of 120,536 km Mass: 5.68 x kg Distance from Sun:1,429.4 million km Distance from Earth: Max 1,579 million km Min 1,279 million km Atmosphere:Mainly hydrogen and helium Temperature: -180 o C at the surface 12,000 o C at the core Length of Year: 10,750 Earth days Length of Day: 10 Earth hours 14 minutes Moons: 31+ (Titan, Iapetus, Dione, Encelaus, Mimas) Colour:Beige Core: Rocky iron core Saturn

Saturn is a ‘gas giant’, like its larger neighbour Jupiter. Saturn ring system is the most spectacular in all the Solar System. These rings are made up of billions of rock particles ranging from a few microns to a few meters in length. The planet’s density is so small that it could float on water. Saturn

Uranus Size: Diameter of 51,118 km Mass: 8.68 x kg Distance from Sun:2,875 million km Distance from Earth: Max 3,025 million km Min 2,725 million km Atmosphere:Hydrogen, helium, methane Temperature: -214 o C Length of Year: 30,707 Earth days Length of Day: 17 Earth hours 12 minutes Moons: 21+ (Oberon, Titania, Umbriel, Ariel, Miranda) Colour:Blue/green Core: Rocky ice core

Like Jupiter, Saturn & Neptune Uranus is a planet made almost entirely of hydrogen, helium and methane gas. Uranus appears blue due to its atmospheric methane that absorbs red light from the Sun. Uranus is a featureless planet. Enhanced imaging shows seasonal atmospheric changes Uranus is the only planet to spin on its side. Uranus

Neptune Size: Diameter of 49,532 km Mass: 1.02 x kg Distance from Sun: 4,504 million km Distance from Earth: Max 4,564 million km Min 4,354 million km Atmosphere:Hydrogen, helium and methane Temperature: -220 o C Length of Year: 60,202 Earth days Length of Day: 16 Earth hours 7 minutes Moons: 11+ (Triton) Colour:Deep blue Core: Rocky ice core

Neptune is one of the four ‘gas giant’ planets, composed almost entirely of gas. Voyager 2 spotted a small white cloud shooting around Neptune’s upper atmosphere every 16 hours. Neptune has the wildest weather in the Solar System, with winds of up to 2,000 km/h During certain points in its orbit Neptune becomes the furthest planet from the sun. Neptune

Pluto Size: Diameter of 2,300 km Mass: 1.27 x kg Distance from Sun:5,915 million km Distance from Earth: Max 7,525 million km Min 4,275 million km Atmosphere:Thin nitrogen atmosphere with carbon dioxide and methane Temperature: -223 o C Length of Year: 90,803 Earth days Length of Day: 6.39 Earth days Moons: 1 (Charon) Colour:Unknown Core: Unknown

Pluto is the furthest planet from the Sun, except for a 20 year period in its 248 year orbit when it comes closer to the Sun than Neptune. Hubble telescope images show light and dark regions Lighter areas are probably ices of nitrogen, methane, ethane and carbon dioxide. Darker areas may be a result of chemical reactions driven by cosmic rays. Pluto

Asteroids Asteroids are lumps of rocky debris that float around in the Solar System. Most are found in the asteroid belt between Jupiter and Mars. They range in size from tiny dust particles to nearly 1,000 km across. Class C: silicates Class M: nickel + iron Class S: nickel + iron + silicates

Comets are icy chunks of water and dust that originate in the outer Solar System. When comets approach the Sun they vapourise, hence developing a bright tail. Comets originate from two regions, the Kuiper Belt and the Oort Cloud. The Kuiper Belt extends from Neptune out past Pluto. The Oort Cloud surrounds the entire Solar System. Comets