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How did the Earth begin?
Around 4.6 billion years ago, a cloud of gas and dust swirled around our newly formed Sun. Gradually, the grains of dust and gas were pulled together into clumps by their own gravity. These clumps became the Earth and the other planets in our Solar System.
What was the early Earth like?
The early Earth was a fiery ball. It took half a billion years for its surface to cool and form a hard crust. As it cooled, the Earth gave off gases and water vapour which formed the atmosphere.
'Scientists have built up a
picture of our Solar System's
birth, as the planets were
slowly formed around the Sun.'
How big is the Earth?
Satellite measurements show it is 40,030 km around the equator and 12,757 km across. The diameter between the poles is slightly less, by 43 km. The weight of the Earth is 5.972 × 10²⁴ kg, surface area is 510,065,623 km² and volume is 1.08321×10¹² km³.
When was the Earth born?
Our planet has not always existed. In fact, the Earth is a relatively young planet. Scientists believe that the Universe may be 13.7 billion years old. But Earth along with the rest of our Solar System was born only about 4.6 billion years ago.
'Our Solar System formed
from a gas and dust cloud.'
What is the Earth made of?
The Earth has a core consisting mostly of iron and a rocky crust made mostly of oxygen and silicon. In between is the soft, hot mantle of metal silicates, sulphides and oxides. Nitrogen is most founded gas.
What shape is the Earth?
The Earth is not quite a perfect sphere. The spinning of the planet causes it to bulge at the equator. Scientists describe Earth's shape as 'geoid', which simply means Earth-shaped! The poles, the Earth's most northerly and southerly spots, are the points the Earth spins around.
'The Earth's oldest rock is
about 4.37 billion years old.'
How Old are Oceans?
The oceans were formed between 4.2 and 3.8 billion years ago. As the Earth cooled, clouds of steam became water, creating vast oceans.
Which are Inner Planets?
The Earth is the largest of the four inner planets, which lie closest to the Sun and are mostly made of rock. These four planets are Mercury, Venus, Earth and Mars, with our planet being third from the Sun. The Earth is the only planet in the Universe on which life is known to exist.
How long is a day on Earth?
A day is the time the Earth takes to turn once. The stars move to the same place in the sky every 23 hours, 56 minutes and 4.09 seconds (the sidereal day). Our day (the solar day) is 24 hours, because the Earth is moving around the Sun, and must turn an extra degree for the Sun to be in the same place in the sky.
'Summer - As the Earth orbits the Sun,
the hemisphere of the planet tilted
towards the Sun has its summer.'
Does the Earth spin?
The Earth spins on its axis once a day, while also orbiting or traveling around the Sun.
How long is a Year on Earth?
The Earth travels around the Sun every 365.24 days, which gives us our calendar year of 365 days. To make up the extra 0.24 days, we add an extra day to our calendar at the end of February in every fourth year, which is called a leap year and then we have to knock off a leap year every four centuries.
What is the Atmosphere?
The Earth's atmosphere, or 'Air' is a layer of gases including nitrogen, oxygen, argon and carbon dioxide that surrounds the planet.
'Sunset - The Earth turns on its axis
once every 24 hours,
so the Sun appears to rise
in the east and move across the
sky to set in the west.'
What's special about the Earth?
The Earth is the only planet where temperatures are right for liquid water to exist on the surface. It is also the only planet with oxygen on its atmosphere. Both water and oxygen are needed for life to exist.
Who discovered the Earth revolves around the Sun?
In the 1500s, most people thought the Earth was fixed in the centre of the Universe, with the Sun and the stars revolving around it. Nicolaus Copernicus (1473-1543) was the Polish astronomer who first suggested the Earth was moving around the Sun.
What is Moon?
The Moon is the Earth's natural satellite. Natural satellites, or moons, are objects that orbit a planet or other body in space. Our Moon is a rocky ball about a quarter of the Earth's diameter. It is held in its orbit around the Earth by gravity.
How is the Moon formed?
The Moon has circled the Earth for at least 4 billion years. Most scientists believe that the Moon formed when, early in Earth's history, a planet smashed into it. The impact was so great that nothing was left of the planet but a few splashes thrown back up into space. These splashes and material from the battered Earth were drawn together by gravity to form the Moon.
'Moon dust - The Moon's surface is
covered with a fine layer of dust.
Beneath lies a crust of rock.'
Are there other Moons?
As many as 240 bodies, all in our Solar System, are classified as moons. Other stars and their planets are likely to have moons, but none has yet been observed.
What is Moonlight?
The Moon is by far the brightest thing in the night sky. But it has no light of its own. Moonlight is simply the Sun's light reflected off the dust on the Moon's surface.
'Tides - As the Earth spins,
the Moon's gravity
makes the ocean rise.'
How is the Tides formed?
Tides are caused by the oceans, on the side of the Earth facing the Moon, being pulled by the Moon's gravity more than the solid Earth itself. On the opposite side of the Earth, the water is actually pulled less than the Earth. This creates a bulge of water on each side of the world. This bulge stays under the Moon as the Earth turns.
Why does the Moon have craters?
The Moon's surface is covered with impact craters. These form when asteroids and comets crash into the Moon. Most of the craters were made about 3-4 billion years ago.
'Lunar seas - People once thought
the Moon's dark patches were
filled with water.
In fact,
they are formed from lava.'
What are the Moon's Seas?
The dark patches on the Moon's surface are called seas, but in fact they are not seas at all. They were formed about 3 billion years ago when lava from inside the Moon flowed into huge craters and then solidified.
Who were the first people on the Moon?
The first men on the Moon were Neil Armstrong and Buzz Aldrin of the US Apollo II mission. They landed on the Moon on 20 July, 1969. As Armstrong set foot on the Moon, he said: ‘That's one small step for (a) man, one giant leap for mankind.’
'The footprint was made
on the Moon's surface
during the Apollo II
mission.'
How long is a month for Moon?
It takes the Moon 27.3 days to circle the Earth, but 29.53 days from one full moon to the next, because the Earth is moving as well. A lunar month is the 29.53 days cycle. Our calendar months are entirely artificial.
What is a Lunar Eclipse?
As the Moon goes around the Earth, sometimes it passes right into Earth's shadow, where sunlight is blocked off. This is a lunar eclipse. If you look at the Moon during this time, you can see the dark disc of the Earth's shadow creeping across the Moon.
'The Moon appears to wax (grow)
and wane (shrink) every
29.53 days.'
What is a Harvest Moon?
The harvest moon is the full moon nearest the autumnal equinox (when night and day are of equal length). This moon hangs bright above the eastern horizon for several evenings, providing a good light for harvesters.
What is a New Moon?
The Moon appears to change shape during the month because, as it circles the Earth, we see its bright, sunny side from a different angle. At the new moon, the Moon lies between the Earth and the Sun, and we catch only a crescent-shaped glimpse of its bright side.
What is Moon Waxing?
Over the first two weeks of each month, we see more and more of the Moon's bright side until full moon. As the Moon appears to grow, we say that it is waxing.
Why does the Moon look red?
As the Moon passes through the Earth's shadow, the Sun's blue light is scattered by Earth's atmosphere. The remaining red light is refracted, or bent, into Earth's shadow. This makes the Moon appear red.
Other silent features of the Moon?
As the brightest object in the night sky, the Moon has always fascinated humankind. We have made up stories to explain it and built telescopes to observe it. The Moon is the only celestial body or object in space upon which humans have landed.
Collected by. - Uttar Tamang
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