When a supergiant star runs out of fuel it creates a supernova.Gravity pulls the centre of the star inward very quickly and it collapses into a small ball. The gravity of a black hole becomes so strong that anything close to it gets pulled in, even light. They are called “black” because they absorb all light and nothing is reflected. This black hole was discovered by the Hubble Space Telescope.
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Mercury, the smallest planet and the closest to the Sun, is only slightly larger than Earth’s Moon. Mercury’s surface is very like the Moon, covered by mountainous regions and large basins full of craters. Its atmosphere is mostly hydrogen and helium. Its surface heats up and cools down very quickly, reaching 427°C (800°F) when it is closest to the Sun and falling to -179°C (-290°F) when it is farthest away.
Mercury travels around the Sun every 88 days in an oval-shaped orbit, taking it as close as 47,000,000km (29,000,000 miles) to the Sun. It travels at almost 50km (31 miles) per second which is faster than any other planet and that is why it is named after the Roman god Mercury, the winged messenger. The first spacecraft to visit and photograph Mercury was Mariner 10, followed several years later by the MESSENGER spacecraft.
Venus is the brightest heavenly body in our night sky after the Moon and has sometimes been called the morning or evening star. It is surrounded by a dense, cloudy atmosphere, consisting of mainly carbon dioxide and nitrogen, which reflects the sunlight. We cannot usually see through this cloudy layer but NASA’s Magellan mission to Venus used radar to take images of the surface. Venus is similar in size to the Earth, with an equatorial diameter of 12,104km (7,521 miles). Venus rotates in the opposite direction to the other planets, so on Venus the Sun rises in the west and sets in the east. Venus takes 225 days to orbit the Sun and 243 days to complete each rotation about its axis, making each day on Venus 117 Earth days long. Its surface is made up of volcanoes and plains, the two major plains being Ishtar Terra and Aphrodite Terra.
The Russian spacecraft Venera 13 landed on Venus but only survived for 127 minutes due to the immense crushing pressure and high temperature on the surface.
The planet Venus is named after the Roman goddess of love and beauty.
Our planet is completely unique in the Solar System. Other planets have atmospheres, seasons and weather but only Earth has life. Earth’s special position in the Solar System – the third planet from the Sun, orbiting at 149,597,871km (92,955,807 miles) – allows life to exist. Any slight change in this distance would be the end of life on our planet.
The Earth is 4.6 billion years old and has an equatorial diameter of 12,750km (7,922 miles). Earth’s axis of rotation is tilted by 23.45 degrees and this gives the planet its four seasons. For part of each year the Northern Hemisphere is tilted toward the Sun and enjoying summer. At the same time the Southern Hemisphere is tilted away from the Sun and is in winter. This then reverses every six months. In March and September both hemispheres have equal amounts of sunlight.
Nearly 70% of the Earth’s surface is covered in ocean and the water vapour in the atmosphere is responsible for most of the weather. The Earth’s atmosphere is mostly nitrogen and oxygen and this forms a layer protecting us from harmful solar radiation and from meteors.
Most of the planets were named after Roman gods and goddesses. However, the name Earth is an old English-German word which just means ground.
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The Moon is a 4.5 billion-year-old ball of rock in space and is Earth’s only natural satellite. The most likely theory about how the Moon was formed is called the Giant Impact Hypothesis. It is thought that a planet the size of Mars collided with the Earth and the resulting debris formed the Moon. As the Moon has no atmosphere it is constantly being bombarded by meteorites and so is covered in impact craters, some billions of years old. The changing faces of the Moon that we see from day to day are known as the Moon’s phases and these are dependent on which part of the Moon is being illuminated by the Sun as it orbits the Earth. In July 1969 Apollo 11 Commander Neil Armstrong became the first man to set foot on the Moon, with the famous words “That’s one small step for man, one giant leap for mankind.”
Jupiter is the fifth planet from the Sun and the largest planet in the solar system, at 1,335 times larger than the Earth.This image shows Jupiter and its four largest moons. Starting top right and moving clockwise they are Io, Ganymede, Callisto and Europa.Jupiter has 67 moons – the most of any planet in the solar system.The four largest moons were discovered by Galileo Galilei in 1610 and were named by Simon Marius in his book of 1614. Io is closest to Jupiter and is the most volcanic body in our solar system. It is thought that there may be twice as much water on Europa as there is on the Earth, with its icy surface covering a huge ocean.Ganymede is the largest moon in the solar system and is bigger than Mercury. It is the only moon to have its own magnetic field.
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The only spacecraft to have visited the sixth planer Saturn are Pioneer 11, Voyager 1 and Voyager 2.This image was taken by Voyager 2 from a distance of 101,000 km (63,000 miles). After studying Saturn Voyager 2 headed to Uranus.Jupiter, Saturn, Uranus and Neptune are often referred to as the gas giants, as they all have a small rocky core with an atmosphere of hydrogen and helium. All the gas giants have rings but none are as magnificent or as visible as those of Saturn. Saturn’s nine rings are made up of small rock and ice particles and extend thousands of km (miles) from the planet.However, the depth of the rings is only 10m (30 feet).Saturn has at least 62 moons, of which only 53 have names and the largest is Titan. Saturn is named after the Roman god of agriculture.
This is a montage of images taken by Voyager 2 showing Uranus and its five major moons. In order of size these are Oberon, Titania, Umbriel, Ariel and Miranda, – all named after characters from works by the famous authors Shakespeare and Pope. Miranda, the smallest of these five moons, has a giant canyon twelve times deeper than our Grand Canyon.The atmosphere on Uranus contains helium and hydrogen but also ammonia and methane and it is the latter that gives the planet its blue-green colour. It is the coldest planet in the solar system and the third largest.Uranus is the 7th planet from the Sun, was discovered by William Herschel in 1781 and is named after the Greek god of the sky.
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