Page:Field Book of Stars.djvu/139

Rh the sun: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune.

MERCURY.

Mercury is the nearest to the sun of any of the planets. On this account, and because of its rapid changes, it is seldom seen.

The most favorable time for observing it is just after sunset, or just before sunrise, during the months of March, April, August, and September, when it may be seen for a few successive days.

The greatest distance it ever departs from the sun on either side varies approximately from sixteen to twenty-eight degrees. Its motion resembles a pendulum, swinging from one side of the sun to the other.

VENUS.

Venus approaches nearer to the earth and is more brilliant than any other planet. It is bright enough to cast a shadow at night, and is sometimes visible even at noonday. It is almost as large as the earth, and oscillates, as Mercury does, on either side of the sun.

It never appears more than three hours after sunset, and as long before the sunrise, and is never more than forty-eight degrees from the sun.

MARS.

Mars is most like the earth of any of the planets, and, although not as interesting an object to view as the