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SCIENCE REPORT - Observing Mars

作者:Mario Ritter 发布日期:6-20-2001

19 Jun 2001, 20:34 UTC

This is the VOA Special English Science Report.

Scientists say this is a good time to observe the planet Mars. Mars changes in brightness more than any other planet. In June and July, Mars will shine brighter than Sirius, the brightest star in the sky. Mars is also interesting to watch from week to week because it moves among the stars more quickly than other planets. Mars is known as "the red planet." In fact, it is bright orange.

This month, you can observe Mars best around the middle of the night. If you face directly south, Mars will be the brightest star before you. If you live in the northern half of the world, Mars will be low in the southern sky, near the star group called Scorpius. But Mars will be almost overhead if you live in the southern half of the world. You can easily recognize Mars because of its brightness and orange color.

This month, Mars will be especially bright for two reasons. About every two years, Mars reaches a point opposite the sun in our sky. A planet is said to be at "opposition" when this happens. Mars reached opposition on June thirteenth.

Mars also has an unusual orbit. The distance from Earth to the sun changes very little because Earth's orbit is almost a perfect circle. But Mars' orbit is shaped more like an egg than a circle. So its distance from the sun changes much more during the Martian year.

On June twenty-first, "the red planet" will be about sixty-seven million kilometers from Earth. This is the closest Mars has been since Nineteen-Eighty-Eight.

You can see changes in Mars' distance from Earth at opposition most clearly by using a telescope. This year, even a small telescope will show that Mars is round like a very small full moon. A larger telescope will show markings that are caused by different qualities of the Martian soil. Some areas reflect more sunlight than others do. On Earth, we see these differences as spots or markings of different colors.

A telescope also will show that the north and south poles of Mars are covered with ice just like the Earth's poles. Even huge dust storms have been seen in the Martian atmosphere.

Mars has captured the human imagination for thousands of years. Its changes in brightness and its movement through the sky make Mars a special sight. Next week we will tell more about Mars, the mysterious "red planet."

This VOA Special English Science Report was written by Mario Ritter.

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