Posted by Art on November 18, 1997 at 14:27:23:
In Reply to: Questions posted by L.C. on November 17, 1997 at 23:58:44:
: Why are there so few craters on the maria?
: Why is Mercury so difficult to observe?
: When is the best time to observe Mars from Earth?
: What is the current knowledge concerning life on Mars?
: HOw do astronomers detect the presence of a magnetic field
: in hot gases, such as those in the solar photosphere?
: Please help! I can't answer these questions from the book.
Note: Each of these questions might take a paragraph to answer. Here are the short answers. If you need more info, see me in office hours, or ask to clarify one question.
1. Because the maria are younger than the heavy bombardment stage. Review dating by crater counts.
2. Because it is always close to the Sun
3. Favorable Opposition
4. Apparently no life at present. There may have been microbial life in the water on Mars in the past. There is some evidence for fossil microbial life on Mars in mertorites from Mars, but the evidence is controversial.
5. By split atomic spectral lines
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