Earth
Earth is the only planet in the solar system where the existence of life has been confirmed. It is the fifth largest planet and the third planet from the sun. Unlike every other planet whose name comes from the Greek or Roman mythology, Earth’s name comes Old English. Earth is also the only planet that can be studied almost completely without any outer space travel. But outer space travel is also useful in studying the Earth as it can help in weather prediction.
Distance from the Sun: 149,600,000 km
Diameter: 12,756.3 km
Mass: 5.97224 kg
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Composition
The Earth has different compositions for almost every different layer. For example, the inner core is solid while the outer core along with the mantle are more like in molten state. The core itself is made of iron. In brief, the composition of the Earth can be divided into:
34.6% Iron
29.5% Oxygen
15.2% Silicon
12.7% Magnesium
2.4% Nickel
1.9% Sulfur
0.05% Titanium
The presence of plates is an interesting feature on the Earth not found on any other planets. The surface of the Earth is not all in one piece, but broken up into several enormous pieces called plates, some as large as continents. The area where two plates meet is called the plate boundary. Another thing about plates is that they are continuously moving, as they float on a layer of molten rock called magma. When two plates move away from each other the magma from below rises to fill up the crack, hardens and forms new crust. When two plates collide, one plate is forced under the other, causing earthquakes.
The Earth’s atmosphere is one of the most complex atmospheres in the whole solar system. It includes a numerous amount of gases, which you will find on the page for Venus, under “Earth vs. Venus”. Though carbon dioxide is a very important gas and is vital for the survival of the Earth, it is present in very small amounts at 0.04%. This is why Earth is not like Venus, where there is so much carbon dioxide and other greenhouse gases that the temperature is extremely high.
The Moon is the only natural
satellite the Earth has. It has many names—Artemis and Luna among others. The
Moon is the brightest object in the sky other than the Sun and has been known
since prehistoric times. Because of its size and composition, the Moon is
sometimes classified as a terrestrial planet. The Moon was visited first by the
Soviet Union’s Luna 2. It was first visited by humans in 1969 and last visited
in 1972. The Moon has been painstakingly mapped by the Earth and is the only
space body of which we have samples (“moon rocks”).
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Fact File
Distance from Earth: 384,400 km
Diameter: 3476 km
Mass: 7.3522 kg
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Phases of the Moon
Except for the days of the full moon and the new moon, we see the Moon as having a dark side—this is a phase. This is because, as the Moon orbits around the Earth, the angle between the Sun, the Moon, and the Earth changes; these are the moon’s phases. The time between the consecutive new moons is 29.5 days.
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Did You Know?
1.Due to the moon, the Earth’s orbit is slowing down by 2 milliseconds every 100
years. This may seem like a little but actually 900 miilion years ago there were
418 days in a year, each being 18 hours long!
2.Without carbon dioxide, the Earth’s average temperature would be -21 C.
3.Scientists say that Earth is a very young planet, but actually it is 4.5 to
4.6 billion years old.
4.The Greeks and the Romans have their own names which are Gaia (terra mater)
and Tellus (fertile soil) respectively.
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