January 20-22, 2015
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| FIGURE 01 |
Let's examine Figure 01, depicting the southwest backyard sky at about 6:15 p.m. on January 20, 2015. This is a
time when a half-dozen stars are visible in your evening sky. Features include
the positions of the Moon, Mercury, Venus and Mars.
A line drawn from
the "S" which stands for South and to the "W" which stands
for West would be the horizon if you were standing on a boat in the middle of
the ocean.
The Moon in our
setting is just above the South-West horizon.
It is an eleven hour moon. At
7
Technically above
the horizon, practically it would be very difficult to observe the 11-hour moon
this close to the horizon, even though you were trying to observe it atop a
large sand dune in the middle of the Sahara.
Only 0.4 percent of the moon is illuminated. Figure 02 illustrates how little this
is.
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| FIGURE 2 |
The illuminated crescent part of the moon does not present a continued light line, but is broken up in places due to the moon's crater walls seen edge on.
The brightest image
in our sky is the planet Venus. It is the anchor in this our second posting of
four; since our last posting of January 10th, when Venus and Mercury were very
close in the sky. Now, just ten days
later, Mercury has peeled off to the west and below Venus.
Mars is above
Venus. It will be interesting to watch
from one evening to the next as their separation decreases.
January 21, 2015
Just 24 hours
later, we note from comparisons of last
evening sky to this, the increasing separation between Venus and Mercury. (Fig.
03)
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| FIGURE 3 |
Last evening the
Moon was 11 hours old. This evening it is 11 hours old plus 24, or 35 hours
old. It has increased from 0.4 percent
illumination last evening to 1.3 percent this evening. (Fig.04)
This evening
marks the first evening when the crescent moon is an easy target for the
backyard observer. Finding the moon's
position is aided by its close proximity to the planet Venus. Two nights and
three days ago the moon was an equally visible object in the morning sky
immediately before sunrise. Two nights
and three days equal 72 hours. It took the moon 72 hours to pass from the
morning sky to the evening sky. Half of 72 is 36. We have a 35 hour moon this evening in good
agreement of a standard two nights and three days traditional description of
the dark of the moon, when the moon is not visible to the unaided eye.
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| FIGURE 4 |
The Greek goddess
of the Moon was Artemis. As the goddess of transitions she was a goddess of
birth and death. The crescent moon
mythically died two nights and three days ago but now reborn as a crescent in
this evening sky. A Greek word to describe a thin crescent moon is the word
"Cynthia," abbreviated as "Cindy." Parents in search of a
name for their newborn find Cynthia listed as another name for the Moon goddess
Artemis. This is a translation I would
expect from a high school guidance counselor or worse yet, from a gym coach. An
appropriate sense of the name Cynthia is: "She who hunts among the
clouds."
The separation of
Venus and Mars continues to decline.
January 22, 2015
This is the evening
sky at about 6:20. (Fig. 05)
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| FIGURE 5 |
Note the position
of Mercury. It is getting very low and by month's end will rise and set at the
same time as the sun.
In just 24 hours
the moon has changed its position from the west of Venus to the west of Mars.
If we could pace the apparent distance the moon traveled from last evening to
this evening, multiply it by 29.5 times, we would have marked a great circle
around the sky. We would find the moon back to the same phase as tonight. This
number is near the 30 day cycle of the month.
The month does indeed get its length from this, the Synodic cycle of the
moon.
The moon is 9
percent sunlit. (Fig. 06)
I refer to this phase of the moon as the Romantic
Moon, because it will take the moon 2.5 hours to set; more than enough time to
accomplish the tasks at hand.
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| FIGURE 6 |
