Equal parts day and night
By Vernon Whetstone
Have you seen comet PanSTARRS? As of this writing I haven’t.
You still have some time to catch a glimpse in the western sky about a half-hour to 45-minutes after local sunset. Which, now that Daylight Savings Time has kicked in, will be at about 7:05 p.m MDT.
On Wednesday, March 13, if the sky is clear to the west, it will be directly below the crescent moon in the west.
Spring is about to be sprung. One week from today the Sun will cross the celestial equator heading north on what is called the vernal equinox. That will happen at 5:02 a.m. MDT.
Equinox is a word from Latin meaning equal night, and on that occasion the expanse of day and night will be equal.
Well, that would be true if you were living on the equator. However, since we in this area are about 40 degrees north of the equator, that will not be the case.
In fact, the date when our day and night will be equal is Sunday, March 17. That is when day and night will both be exactly 12 hours.
There are other astronomical signs of spring. In the west the constellation Pegasus—an autumnal constellation—is setting. In the east Leo—a spring constellation—is rising.
In the south, Orion, the King of Winter, is standing upright, and in the north the Big Dipper asterism is standing upright on its handle.
In other happenings around the sky the moon and Jupiter will, once again, have a very close conjunction on March 17. Look almost directly overhead facing west about an hour after local sunset.
The bright star on the other side of the moon is Aldebaran, the Eye of the Bull in Taurus.
There will only be two more close groupings of the moon and Jupiter before the giant planet goes behind the Sun for the next several months.
They will be on April 14, and May 12, so get your sightings in now.
Another spring event can be a difficult one to find. It is called the Zodiacal Light.
In the spring it can be seen after sunset, in the fall it will be seen before sunrise.
It is basically sunlight reflected off of inter-planetary dust particles in the inner solar system. This dust is accumulated along the ecliptic (the path the Sun follows against the background stars).
In spring and autumn it is at a very high angle to the horizon so is much more pronounced than at other times of the year.
First you will need a very dark-sky place away from all city lighting. It will be in appearance very similar to what the Milky Way looks like on a dark summer night, a very hazy looking light area right over where the Sun went below the horizon.
It will extend up into the sky in a cone of light, possibly as far as directly overhead. Start looking at sunset and then keep watching. The sky will look like the Sun is still setting.
When this phenomenon occurs in the morning it has been called a “false dawn” because it will look like the Sun is rising a long time before it actually will.
SKY WATCH: First quarter moon, March 19; vernal equinox, March 20. Saturday, March 16, a slender five-day old crescent moon will be very close to the Pleiades star cluster, look almost overhead facing west.