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Topic: Astronomy
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The Earth is 4.5 billion years old. It is 4500 ° C in the center of the earth.
Earth is 12,700 km in diameter. The Earth is not perfectly round.
70% of the Earth is covered by water.
The outermost of the planet's crust and is 30-40km thick.
The Earth's atmosphere has no direct stop but it is about 1000 km thick.
The Earth spins once around its own axis at 23h and 56min and just
it spins, we get night and day. And it revolves around the sun at 365.25 days.
There are those here 0.25 which means that we have a leap year every four years.
The earth is tilted for us to be able to get the seasons.

The Moon

The Moon rotates just like the earth makes fixed rather than rotating around
sun moon rotates around the earth. Lunar surface is covered with craters and plains.
The craters have emerged for the moon was hit by large boulders
nearly 10 million years ago. The Moon's highest mountain is 8000 m.
The distance between the Earth and the Moon is 380,000 kilometers.
Moon's diameter is 3200 km. The moon is about one quarter the size of Earth's. Moon's surface temperature is from -160oC to +110 oC.
The first manned spacecraft landed on the moon was 20 July 1969, Neil Armstrong was the first man who walked on the moon.
His footsteps will be left on the moon for several millions of years to the moon has no atmosphere, so why blow it nothing there. The moon's gravity is one sixth of the earth. So you can lift 50kg on Earth you can lift 300kg on the moon.
The moon is also called Luna.


The sun is a star. It looks so great in comparison to those other stars is because it is so close. It takes 8min for a ray of sunshine coming from the sun to the earth. The distance between Earth and the Sun is 150 million kilometers.
The sun's diameter is 1,392,000 kilometers. The temperature of the surface is 6000oC.
And in the middle is 15 million ° C. The sun is 4.6 billion years old.
Every second, the sun loses 4.5 billion tons of its weight.
Scientists estimate that the sun will be shining in about 5 billion years.
If one were to go by car to the sun, it would take about 200år.

Solar and lunar eclipse

The moon moves in orbit around the earth, and the earth orbits around the sun.
Sometimes it happens that the sun, moon and earth are aligned but each other. Depending on whether the scheme is sun-moon-earth or sun-earth-moon we get solar eclipse or lunar eclipse. A solar eclipse lasts for a maximum of 7min. The last eclipse in Sweden was in 1954 and the next solar eclipse coming year 2126th

The planets

In the solar system are those nine planets. Mercury, Venus, Earth and Mars are quite similar. They consist of a large part of the stone and the planets are quite small.
Jupiter, Saturn, Uranus, Neptune, belongs to the giant planets.
They consist of liquid and gaseous matter. Pluto believe it is quite similar to the first four. The word planet comes from the Greek and means to wander.
The planets shines not of themselves, they become visible by the light from the sun is reflected. The planets move in oval orbits around the sun.
They webs called ellipses.


Comets consist of frozen gas, gravel and ice. Comets travel around the Sun at regular intervals. Comets move in elliptical orbits around the sun.
The point in the track when the comet is closest to the sun is called "perihelion".
They are usually far away in the solar system's edge. And when they come closer to the sun becomes part of the comet gas, and they have a tail. The tail always points away from the sun (when the comet go out again the sun goes tail then first).
Sometimes you may see two tails. The comets visible from a few days to a few months. On average, a comet 8-15 km in diameter.

Comets after 1950
• Comet Hale-Bopp in 1995
• Huyakutake 1996
• West 1996
• Kohoutek 1973
• White-Ortiz-Bolelli 1970
• Bennett 1969
• Ikeya-seki 1965
• Seki-Lines 1962
• Wilson-hubbard 1961
• Mrkos 1957
• Arend-Roland in 1957


Between Mars and Jupiter there is a belt where there are very many minor planets. And these småplaneterna called asteroids.
The first asteroid was found in 1801 and named it Ceres.
Then they found Pallas, Vesta and Juno.
But now they have found several thousand. Ceres has a diameter of 1000km.
Most other asteroids usually have a diameter of 1km or minde.
So Ceres mass is almost half the mass of all the asteroids in the belt.
If a large asteroid could hit the Earth would probably all living things die.


Asteroids that is less than 100m in diameter is called meteorites.
The meteorite is a large stone. Will a meteorite into the Earth's atmosphere to burn up. It can happen that a meteorite might hit the earth's surface.
It is rare that a meteorite will alone.
They usually come down about ten at a time.


Mercury is the closest planet to the sun. It is very small,
just a little larger than our moon and Mercury's surface resembles our moon's very much. Mercury has no atmosphere. The temperature in the day can rise above 420ºc.
And at night it can drop to -108ºc. Mercury has no moon


Venus is similar in size to Earth. It has a diameter of 12 104km. The temperature of the surface is 740ºc. It takes 225 days for Venus to rotate around the Sun, and 243 days to rotate around its own axis.
Venus has no moon.


March is called the red planet because it appears red if you look at it with only the eyes. Mars is about half the diameter of Earth,
Mars 6 786km. It takes 1.88 years for it to rotate around the Sun,
and 24.6 hours around its own axis. Before, March volcanoes but they have gone out. Mars has two moons (Phobos and Deimos).


Jupiter is the largest planet in our solar system. It has a mass greater than all the other planets combined. In Jupiter's center is 20 000ºc.
The diameter is 142 984km. It takes 11.86 years for Jupiter to rotate around the Sun, and about 10 hours for Jupiter to rotate once around its own axis.
Jupiter has 16 moons.


Saturn is the second largest of the nine planets. It has a ring around it.
Or actually it is at least 10,000 rings. The rings are made up of ice and gravel.
The diameter is 120 536km. In Saturn's center is 15 000ºc.
It takes 29.46 years for Saturn to rotate around the Sun, and to rotate once around its axis takes 10.65 hours.
Saturn has 18 moons, the largest of them is called Titan.


Uranus was discovered in 1781. It is blue-green. It has a diameter four times the diameter of the earth. It takes 84.01 years for Uranus to rotate around the Sun and around its own axis, it takes 17.2 hours. Uranus has 15 moons.


It was discovered in 1989. Neptune is equal Uranus.
It has a diameter of 49 528km. It takes 164.79 years for Saturn to spin around the Sun and around its own axis, it takes 16.1 hours. Neptune has 8 moons.


Pluto was discovered in 1930 by accident. Pluto is the smallest planet of the nine. It is even Minde than our moon. The distance between the Sun and Pluto is 5.9 billion kilometers. Pluto diameter is 2300km.
And the temperature is at -230oC. Pluto has its own moon named Charon.
It was discovered in 1978. It is quite big if you compare but the Pluto. Charon's diameter is 1265 km. Pluto rotates around the sun in 247.7 years.
And it rotates on its axis at 153h.
Pluto is 70% rock and 30% water ice.

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One Response to "Astronomy"

  1. Bjorn R on December 6, 2008 at 10:38 pm #

    If the moon's diameter is 1/4 of Earth's diameter, it does not mean that the moon is a quarter as large as the Earth.

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