home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
CD School House 9
/
CD School House 9.0 - Wayzata Technology (1994).iso
/
pc
/
dos
/
sciences
/
acecalc
/
descrip.dat
/
l02.dal
< prev
next >
Wrap
Text File
|
1994-02-18
|
1KB
|
19 lines
eak general magnetic field.
$
MERCURY
At just over one-third earth's distance from the sun, Mercury is the solar
system's innermost planet and the only one known to be almost entirely without
an atmosphere. Mercury is a small world only 6% as large as earth by volume--
barely larger than our moon. One hemisphere of Mercury is extremely heavily
cratered, in many respects identical in appearance to the far side of earth's
moon. Mercury's orbit is the most elliptical of any planet except Pluto's.
Mercury's sidereal rotation period is the longest of any planet.
Mercury has a tight orbit that constrains the planet to a small zone on either
side of the sun as viewed from earth. When Mercury is east of the sun, we may
see it as an evening star low in the west just after sunset. When it is west
of the sun, we might view Mercury as a morning star in the east before sunrise.
Because of celestial geometry involving the tilt of earth's axis and Mercury's
orbit, we get much better views of Mercury at certain times of the year. The
best time to see the planet in the evening is in the spring, and in the
morning in the fa