There are nine planets in our Solar System. All our planets circle around the sun. Some people believe the Solar System is made up of two parts. The first is the Inner Solar System which has Mercury, Venus, Earth and Mars. These are closest to the sun and are called the terrestrial planets because they have very solid rocky surfaces. The Outer Solar System has Jupiter, Saturn, Uranus, Neptune and Pluto. Our Solar System also contains comets, moons, dust, gas and some minor planets.

 Mercury is the closest planet to the Sun. It is 36 million miles away!  Mercury orbits the Sun, which takes only 88 days. When it orbits, it travels 36 million miles.  It was named after the messenger of the Roman Gods.  Mercury only turns very slowly on its axis, taking 59 days to complete the turn from day to night.  Mercury’s sunny side has a temperature rising to 400° Celsius.  Mercury’s dark side, however, is very cold indeed, with the temperature going down to -200° Celsius.  Mercury has no atmosphere around it.  Mercury is quite a small planet. Its diameter, the distance right round its middle, is only 3100 miles.  Mercury has no moons.  The surface of Mercury is covered with craters and completely dry. There is no possibility of life on Mercury.

 Venus is the brightest planet in the Solar System.  Venus orbits the sun in 225 days. A year on Venus only lasts for 262 days!  Venus is the 2nd planet from the sun.  Venus is called after the Roman Goddess of love and beauty.  Venus is the planet which is closest to the Earth.  The circumference of Venus is 7520 miles.  Venus has no moons.  Venus is 67 million miles from the Sun.  Venus is covered by clouds of water vapour and sulphuric acid.  Venus is the hottest planet in the Solar System. The temperature on the surface of Venus is about 460° Celsius.  The atmosphere on Venus is composed of carbon dioxide.

 It is the only planet that has an atmosphere containing 21 percent oxygen.  It is the only planet that has liquid water on its surface.  Earth is the 3rd planet from the sun.  It is the only planet in the solar system that has life.  Earth has one moon.  The Earth takes 365¼ days to complete its orbit round the Sun.  As the Earth orbits the Sun it turns on its axis, rotating in 24 hours. The side of the Earth that faces the Sun has daytime and the side of the Earth that is turned away from the Sun has night-time.  As the Earth orbits round the Sun it tilts very slightly and so gives us the seasons.  The Earth is 93 million miles from the Sun.  The Earth’s diameter, the distance round its middle is 7928 miles.

 Mars is often called The Red Planet.  Mars is the 4 th planet from the sun.  Mars is not much farther from the Sun than Earth. As a result, a typical year on Mars is 1 year and 320 days.  A Martian day is 24 hours and 39 minutes long.  Mars has seasons like Earth too. These seasons are much longer than Earth seasons because Mars is so much farther from the sun.  On Mars is the largest mountain in the solar system at more than 25 kilometers high (that’s three times higher than Mount Everest).  The temperature on Mars regularly drops to -82 degrees Celsius in the winter and only rises to -5 degrees Celsius in the summer.  The dust storms on Mars are larger than on any other planet in the solar system.  Mars is covered by craters from objects like asteroids and meteorites hitting the planet.

 Jupiter is the giant of the Solar System, with a mass more than 300 times the mass of the Earth.  It is named after the ancient Roman sky-god, Jupiter, known to the Greeks as Zeus.  Jupiter has a diameter of 88,700 miles.  Jupiter is the fifth planet from the Sun.  Jupiter spins round much faster than Earth, turning on its axis once every 9.84 hours!  Jupiter is the stormiest planet in the Solar System. There is a permanent, but ever-changing whirlpool of storms, known as Jupiter’s Great Red Spot.  Jupiter is the first of the “gas giants”.  Jupiter is made of hydrogen, helium, methane and ammonia. The cloudy sphere has bright belts on it which change their shape.  Jupiter has 64 moons in total, four of which are large enough to be seen with a small telescope.

 Saturn is the 6 th planet from the sun.  The bright globe of Saturn is surrounded by rings which may be composed of ice.  The rings were first seen by Galileo in 1610 through a telescope.  Saturn has at least 18 moons.  Saturn is named, like all the planets, after a Roman God. Saturn was a rather mysterious God but it is believed that he was the God of sowing seed and of the harvest.  Saturn is the second largest planet in the Solar System, after the giant Jupiter.  Its mass is 95 times that of the Earth and it has a diameter of 75,098 miles.  Saturn is 886 million miles from the sun.  The Earth completes one rotation on its axis in 24 hours, turning away from the Sun and back again to give us night and day. Saturn completes a full rotation in just over 10 hours.

 Uranus is the 7 th planet from the sun.  Uranus has a total of 27 moons, most of whom are named after characters in Shakespeare’s Midsummer Night’s Dream.  Uranus orbits the Sun lying on its side and takes 84 years to complete one orbit.  Because Uranus is lying on its side as it orbits the sun, for nearly a quarter of its orbit one pole of the planet is in complete darkness.  Uranus takes 17.9 hours to turn once on its own axis, faster than the Earth, which takes 24 hours and gives us the change from day to night.  Uranus was the ancient Greek God of the heavens whose sons were the Giants and Titans.  Uranus is the smallest of the four “giants”, but is still several times larger than the Earth. It has a diameter of miles.  Uranus is 1782 million miles from the Sun.  Most of the centre of Uranus is a frozen mass which gives it the blue green colour. The atmosphere also contains hydrogen and helium.

 Neptune is the 8 th planet from the sun.  They named it Neptune after the Roman God of the Sea.  Neptune is the third largest planet in the Solar System.  Neptune has a diameter of 29,297 miles.  Neptune is a great ball of hydrogen and helium.  It takes Neptune 165 of our Earth years to orbit the Sun. The Earth orbits the Sun in 365 days, one year.  The Earth turns right round on its own axis in 24 hours, giving us the change from day to night. Neptune spins slightly faster on its axis, taking just over 19 hours to turn right round.  We now know that Neptune has 13 moons in total.  Since Neptune was the God of the Sea, all the moons are named after less important ancient Greek sea gods.  The Earth is 150 million kilometres from the Sun. Neptune is unimaginably further.

 Pluto was the Roman God of the Underworld.  Pluto is the 9 th planet from the sun.  Of the nine planets which most people think of as being in the Solar system, Pluto is the 2nd smallest, only just bigger than Mercury.  It takes Pluto 248½ years to complete its orbit round the Sun. The Earth takes one year.  Like all the planets Pluto turns on its own axis as it orbits round the sun. Pluto takes about 6½ days to turn on its axis. The Earth takes 24 hours, one day.  Pluto was the Roman God of the Underworld.  Pluto’s distance from the Sun varies. Since the planet was only discovered in 1930 and it takes 249 years to orbit the Sun, a full orbit has not been observed.  Between 1979 and 1999 Pluto was closer to the Sun than the planet Neptune, moving inside Neptune’s orbit.  Pluto has no moons.

A comet is a relatively small solar system body that orbits the Sun. When close enough to the Sun they display a visible coma (a fuzzy outline or atmosphere due to solar radiation) and sometimes a tail. The coma is created as the comet gets closer to the Sun, causing water, carbon dioxide and other compounds to sublime (quickly changing from solid to gas) from its surface. Comets are made of ice, dust and small rocky particles. The name comet comes from the Greek word meaning ‘hair of the head’, it came from the Greek philosopher Aristotle who observed comets as ‘stars with hair’. Short term comets (also known as periodic comets) have orbital periods of less than 200 years while long term comets have orbital periods of over 200 years.

The Sun is a star found at the centre of the Solar System. It makes up around 99.86% of the Solar System’s mass. At around 865,000 miles wide, the Sun’s diameter is about 110 times wider than Earth’s. Around 74% of the Sun’s mass is made up of hydrogen. Helium makes up around 24% while heavier elements such as oxygen, carbon, iron and neon make up the remaining percentage. Light from the Sun reaches Earth in around 8 minutes.

July 20th was the date that the first manned mission to the moon, Apollo 11, landed in men have landed on the moon, the first two were Neil Armstrong and Buzz Aldrin from Apollo 11. Apollo 11 was launched on July 16th, landed on the moon on the 20th and landed back on Earth in the Pacific Ocean on July 24th. The men only spent about 2-1/2 hours on the surface of the moon. Upon stepping on the surface of the moon, Armstrong said, "That's one small step for man, one giant leap for mankind." The astronauts collected soil samples, planted a US flag and left behind a bag of memorial items and extra equipment that they did not need for the return flight, in order to lighten the load. When they returned to Earth, the astronauts were quarantined for 21 days as a precaution, then went on a 45-day "Giant Leap" tour all over the world. Quite a celebration!