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发帖数: 612 | 1 from sci.astro,sci.astro.amateur
Five planets are quite bright in Earth's sky: Mercury, Venus, Mars,
Jupiter, and Saturn.
But how many of these planets would still be visible to the naked eye
if
they were as far as Pluto's mean distance from the Sun (39.5
astronomical
units, or 3.7 billion miles)?
A. All of them.
B. All but Mercury.
C. Only Jupiter and Saturn, the two largest.
D. None of them.
Find out the correct answer at http://KenCroswell.com/PlutoQuestion2.
html .
Correct email: Magni |
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