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  3. Just like the Moon in a solar eclipse, the planet Venus will impose itself f

Just like the Moon in a solar eclipse, the planet Venus will impose itself f

游客2024-08-13  41
问题     Just like the Moon in a solar eclipse, the planet Venus will impose itself for a few brief hours exactly between the Earth and the Sun. But instead of blocking out the Sun, as the Moon does, Venus will only appear as a small black dot against the face of the Sun. This is because Venus is so much further away from us than the Moon.
    The 2004 transit of Venus will be visible in its entirety from Europe, Africa and Asia. Australians can watch the first part of the transit, but it will be after sunset when Venus completes its journey across the disk of the Sun. New Zealanders will have to content themselves with webcasts, as the transit for them begins after the Sun has set.
    Although less spectacular than a lunar eclipse, the transit of Venus is far more unusual. It also has particular significance for Australians because it led to the first British exploration" of the east coast, by none other than Captain James Cook.
    The reason why transits of Venus are so uncommon is that Earth and Venus orbit the Sun in slightly different planes. This difference, about 3.4 degrees, combined with the fact that Earth has a slower orbit than Venus, means that the two planets align with the Sun only twice (eight years apart) every 121.5 or 105.5 years.

    Safe viewing:
    The Astronomical Society of Australia suggests a simple method of viewing, using a small telescope or pair of binoculars.
    Use the telescope or binoculars to project the image onto a piece of white paper or card. With your back to the Sun, aim the telescope towards the paper (use the shadow of the scope as a guide). The paper should be about 20cm behind the eyepiece of the telescope. Focus the image onto the card. Venus will appear as a black spot about 1/33rd the width of the Sun, and should be easily seen.

    Warning:
    Never observe the Sun with the naked eye or through a telescope, camera or other optical device as this can cause almost instant blindness.
    SUMMARY:
    The transit of the Venus is a rare scene. It happens twice every 121.5 or 105.5 years, with an interval of【51】years between the two. There are good reasons for its rareness. First, the Venus orbits the Sun in a different【52】to the Earth’s. The difference is【53】degrees. Second, the Earth orbits【54】than the Venus, which decides that the two planets align with the Sun twice in a long period. Although the Venus transit is less spectacular than a lunar eclipse, it is more【55】, and it has particular significance to Australians, and is very much worth viewing. [br]
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答案 3.4
解析 (文章第四段提到This difference，about 3.4 degrees。)  
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