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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. It is the only planet in the solar system that has life. The Earth is the only inner planet (Mercury, Venus, Earth and Mars) to have one large satellite, the Moon.

Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite.

Radius: 3,959 mi Age: 4.543 billion years Distance from Sun: 92.96 million mi Population: 7.53 billion (2017) World Bank Did you know: The Earth is in a perpetual state of change.

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Questions About Earth Download Questions about Earth (all answers found on this page) The Earth is unlike every other planet in the Solar System in a number of different ways.

It is the only planet that has an atmosphere containing 21 percent oxygen. StartsIt is the only planet that has liquid water on its surface.Advertisement

StartsIt is the only planet in the solar system that has life. Starts The Earth is the only inner planet (Mercury, Venus, Earth and Mars) to have one large satellite, the Moon. Mars has two very tiny moons. Mercury and Venus have none.

StartsThe Earth is fragile. Its surface is split into plates (tectonic plates) which float on a rocky mantle – the layer between the surface of the earth, its crust, and its hot liquid core. The inside of the Earth is active and earthquakes, volcanoes and mountain building takes place along the boundaries of the tectonic plates.

As a result of the Earth’s geological activity (the volcanoes and earthquakes) the surface of the Earth has far fewer craters than the surface of planets such as Mars, Venus and Mercury or the surface of the Moon. The craters have sunk down or been worn away by wind and rain over millions of years.

When viewed from outer space much of the Earth’s surface cannot be seen because of clouds of water vapour. The water vapour makes the Earth, when seen from outside, into a brilliant shining orb, as you can see in Figure

The Earth is the third planet from the Sun and comes between the planet Venus and the planet Mars.

The planets of the Solar System. The Earth takes 365¼ days to complete its orbit round the Sun. The Earth’s year is therefore 365 days long but the ¼ days are added up and every fourth year has one extra day, on the 29th of February. This fourth year is called a Leap Year (366 days) and is always a year which can be divided exactly by 4 – 2000, 2004, 2008, 2012, 2016.

The planets closer to the Sun, Mercury and Venus, have shorter years than the Earth. The planets further away from the Sun have longer years; Pluto takes 249 of our years to make one orbit of the Sun.

As the Earth orbits round the Sun it turns on its axis, rotating right round 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. When it is daytime in Britain, it is night-time on the opposite side of the Earth in New Zealand.

As the Earth orbits round the Sun it tilts very slightly and so gives us the seasons. When the Earth has tilted so that the northern half of the Earth is a little away from the Sun, the northern hemisphere (meaning half of the Earth’s sphere) has winter.

At this time the southern hemisphere is tilted very slightly towards the Sun and the southern hemisphere has summer. Winter in Britain means summer in  New Zealand. Closer to the Equator there is much less difference between summer and winter.

The Earth is 93 million miles, or 150 million kilometers from the Sun.

We can also say that the Earth is 1 AU from the Sun. Astronomers (people who study the planets and stars) use a measurement called an Astronomical Unit, AU. Earth’s measurements are taken as the standard for this system, so Earth is 1 AU from the Sun, Venus is 0.72 AU from the Sun and Mars is 1.52 AU from the Sun. Pluto, furthest out, is 39.5 AU from the Sun. How many million miles from the Sun is Pluto?

The Earth’s diameter, the distance round its middle at the Equator, is 7928 miles, or 12760 kilometers.

The Earth is not an exact sphere; the diameter going round the North and South Poles is slightly less than the diameter round the Equator. The Polar diameter is 7891 miles, or 12700 kilometers. (Try measuring the different diameters of an orange and you will see how they can differ).

The Earth is larger than Mercury, Venus and Mars, the planets closest to it. On astronomy maps it often looks smaller than Venus because Venus is shown with a thick layer of sulphuric acid which lies 40 miles above the

The Earth differs from all the other planets because it has such a wide diversity of life and intelligent beings. This has only been possible because of the Earth’s atmosphere which has protected the Earth and allowed life to flourish.

EARTH'S MOON INFORMATION.

the Moon was probably made 4.5 billion years ago when a large object hit the Earth and blasted out rocks that came together to orbit round the Earth. They eventually melted together, cooled down and became the Moon. For another 500 million years pieces of rock kept striking aginst the surface of the Moon.

You can see the surface of the Moon by using a pair of binoculars or a small telescope. The Moon’s surface shows the damage caused by these large pieces of rock hitting it billions of years ago. The surface is covered in craters, pits and scars.

From the Earth we can only see one side of the Moon; the other side is always turned away from us. Photographs from space show a similar scarred surface on the other side.

The Earth has a much greater surface than the Moon and was also hit by debris (the rocks from explosions and collisions) but over time the damage has disappeared. The wind and rain in the Earth’s atmosphere has helped to erode the pits and craters.

The Moon has no atmosphere and so we can still see the damage caused billions of years ago.

If you look at the Moon when it is nearly full you can see the dark areas which are known as the seas. (They are all given Latin names, such as Mare Serenitatis – the Sea of Serenity, or Mare Frigoris – the Sea of Cold).These are not really seas but are huge expanses of smooth dark lava.

A map of the Moon.All parts of the Moon are lit in turn by the Sun. As it rotates round the Earth we see different fractions of the sunlit half, or hemisphere, of the Moon. These are known as the phases of the Moon, or lunar phases. The Moon changes from a thin crescent to a full moon and back again to a crescent in one month (actually 29 days, which is a lunar month).

from a new moon, which you can hardly see at all, round to a full moon and back again in just over four weeks. Follow the phases in an anticlockwise direction(the opposite way from how the hands of a clock move).

The waxing Moon. “Waxing” means growing. After the new moon appears in the sky as a tiny sliver of light the moon waxes. It grows into a crescent, curving to your left as you look at it and then into a half moon. This takes a week and so the period is described as the Moon’s first quarter.

The waxing gibbous Moon. Gibbous means humped and describes the shape of the Moon as it grows from a half moon to a full moon. Another week has passed and this is the Moon’s second quarter.

The waning Moon. “Waning” means shrinking. Now the Moon begins to get smaller again – it “wanes”. The third quarter takes us from a full moon to a half moon again, but this time it is the right hand side of the moon that shines.

The waning crescent Moon. The last quarter takes us from a half moon back to a crescent moon, facing right, and to a point where the moon disappears.

When the Moon is a crescent and only the crescent is being illuminated by the Sun, you can often see the shadow of the rest of the Moon. This is caused by reflection of sunlight from the Earth. It is sometimes called “the old moon in the new moon’s arms”.

The gravity of the Moon, the pull which it exerts on the Earth, causes two high tides on the Earth every day – one every 12 hours and 25 minutes.

The first man to make proper maps of the moon was Galileo. Galileo did not invent the telescope but by 1609 he had developed a telescope that could magnify objects to 20 times, and with this telescope he began his careful study of the Moon’s surface.

The first person to walk on the Moon was the American astronaut, Neil Armstrong, who stepped out of his space landing craft, the Eagle, on 21 July 1969 with these famous words, “That’s one small step for man, one giant leap for mankind”.

A photograph of the Earth taken from the surface of the Moon.The Moon is 239,000 miles, or 384,000 kilometers away from the Earth.

The Moon is much smaller than the Earth, with a diameter of 2159 miles, or 3476 kilometers. It is airless, no water and lifeless.

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