Astronomy in questions and answers
astronomy in questions and answers
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Mercury, Venus and Mars [Questions 17-21]

17. What are the canals on Mars?

The canals were first described by Giovanni V. Schiaparelli in 1877. He saw through a telescope regular lines on the surface of Mars, which he called "channels", using the Italian word "canali". This was translated into "canals", although there is difference in the two words. A canal means a channel for water made by man, not by nature. A channel is formed by nature.
Since that time, about half the astronomers who have observed Mars have reported seeing the canals, and about half have not seen them. Percival Lowell not only saw the canals, but saw them meeting at various junction points that he called "oases", and saw them doubling at certain times in the Martian year. Others who have seen the canals have reported them as very well defined lines. Lowell also said that the canals could have been built only by intelligent beings; that they were for the purpose of bringing water from the melting polar caps to the equatorial deserts; that a progressive darkening of the canals from the poles to the equator each year showed artificial propulsion of the water, and the fact that the canal system covered the surface of Mars without interruption indicated a system of world civilization there.
When the surface of Mars was photographed in details, it appeared that the canals are an optical illusion. However, some traces of dried rivers were found there.

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18. What is the green on Mars?

There is a seasonal change in the colour of several regions. The green areas on Mars are seen during the Martian spring. They become much darker, almost a blue-green in the Martian summer; yellow and brown in the autumn and grey in the winter.

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19. Does Mars have seasons?

Yes. But its seasons are longer than the seasons of the Earth, because the Martian year is longer. Mars is also like the Earth in that: it is at perihelion during its southern summer, which makes that season shorter and warmer than the northern summer.

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20. Does Mars have any satellites?

Two. They were discovered by Asaph Hall, an American astronomer, in 1877. The inner satellite of Mars - Phobos is about 20 kilometres in diameter and is about 9,000 kilometres from the surface of Mars. It makes a revolution about Mars in 7 hours, 39 minutes. It goes around the planet three times and a little more every Martian day. The outer satellite - Deimos is smaller than the inner satellite, perhaps about 1/3 its size, and is about 24,000 kilometres from Mars. It revolves about the planet in 30 hours, 18 minutes.

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21. Why does Mars look red?

Mars looks red because the material of which its surface is made reflects red light better than it does light of any other colour. Most of the surface of Mars reflects light very much in the same way that sandstone or very dark rock does.

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See also
• The Sun
• The Earth
• The Moon
• Jupiter, Saturn, Uranus, Neptune and Pluto
• Meteors and Comets
• Stars
• The Constellations
• Galaxies
• Scientists and Astronomers

Related Internet Links
• Astro Kids: Mercury
• NASA: The Planets
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