Stardate 03:23:98
A
planetary alignment.... Can you see it?
The
skies this week pose a challenge to amateur astronomers here on Earth.
The
planets Mars, Saturn and Mercury are all aligned together, huddling low
on the western horizon, in the dying embers of twilight. Setting soon after
the Sun, they will be a challenge to find as dusk turns to night.
This
week, we will accept nature's challenge. First, you will need to find an
area with a very low horizon to the west. Try finding a large field, and
stand on the east side of it. Can you see five to ten degrees above the
western horizon? That is what will be required for this week's observing.
Remember, a clenched fist held at arm's length is about ten degrees. This
is an easy method of estimating angles. Also, standing on a hill will help.
Lakesides often provide a low horizon, but the light from astronomical
objects can be refracted by the water vapor from the water, creating a
blurred image. The cool weather at this time of year will, however, minimize
this effect.
The Sun is setting now at about 6 p.m., so go outside about 6:30. The
first planet to observe is the planet Mars. Mars is shining at magnitude
1.3, which would make it one of the 20 brightest stars, if it were a star.
Rusty red in color, Mars can be found just 5 1/2 degrees above the western
horizon, just barely to the north. Telescopes generally have (at medium
power), a field of view of about one degree diameter. Mars is about 4 arcminutes
across, and since there are 60 arcminutes in a degree (and 60 arcseconds
in an arcminute), we can see Mars will produce an image in a telescope
which will have a diameter of about 1/15 that of your entire field of view.
There
are seasonal changes on Mars which can be observed by amateur astronomers
here on Earth. Look over the course of several nights for dark patches,
which seem to migrate across the face of the planet. Mars has always fascinated
Mankind, first with it's bright red color, which earned it the title of
the God of war, and later with the possibility of life on it's surface.
The American astronomer Percival Lowell mistakingly believed he had seen
"canals" on the face of Mars, and Orson Wells stunned the nation
with his rendition of H.G. Wells classic, The War of the Worlds. Recent
discoveries of possible Martian fossils, and the Mars Pathfinder mission
have kept the world enthralled with the red planet. Mars will be setting
at 7 p.m. this week, so you want to observe this planet first.
The second planet we will turn our gaze to this week is the mighty
ringed planet, Saturn. Nearly as bright as Mars, Saturn looks white or
yellow when seen with the naked eye. Look for it sitting 4 degrees away
from Mars, about 8 degrees above the horizon, nearly due west. The second
largest planet in our solar system, Saturn would float on water, if you
could find a lake large enough!
Saturn's
giant Moon Titan is larger than the planet Mercury, and has a thick atmosphere,
and possibly oceans. Cassini, the last of the big budget programs from
NASA is equipped with a special probe called Huygens, which will land on
Titan, hopefully revealing some of it's secrets. Saturn is now orbiting
the Sun at a distance over 9 times as far from the Sun as is the Earth.
The last stop on our tour of the solar system is the innermost planet,
Mercury. Looking much like our Moon, Mercury is even more heavily cratered.
Mercury is a small, airless, lifeless world, and was likely the last planet
discovered. Look for it about 5 1/2 degrees away from Saturn, back toward
the north. This battered world will be found 10 degrees above the horizon,
just slightly north of west, almost directly above Mars. It will be almost
exactly as bright as Saturn, and will appear pure white to the naked eye.