March Skies Show the Change in Season

by Rod Kennedy

March is a time that the snow weary citizens of Wyoming look forward to. After all, March is the
official beginning of spring. This year the Spring or Vernal Equinox occurs on March 20th.
While the March weather in Wyoming is a little too unpredictable to plan extended observing
sessions, there are a number of interesting sights that are easily seen by simply stepping
outside.

Throughout March three planets will be visible in the evening sky. In the west Venus is visible
just after the sun sets. As March progresses Venus will slowly climb out of the glare of the sun
and higher into the evening sky. Mars is visible almost directly overhead just 7o from the star
Pollux in Gemini the Twins. The planet Saturn is rising in the east in the constellation Virgo the
Maiden. Saturn will be at opposition, or directly opposite the sun in the sky, on the evening of
March 21st.

The constellations visible will gradually change during March as well. The constellations of
Autumn, Perseus, Andromeda and Aries are setting in the west. The stars of Spring, Leo, Virgo
and Crater are appearing in the East. The stars of winter, Orion, Taurus and Gemini are slowly
working their way toward the western horizon but will still be visible into April.

In addition to changes in the nighttime sky, the daytime sky will also display changes. For
example, the sun will rise about 4 minutes earlier and set 4 minutes later each day. In addition
the sun will rise due east and set due west on March 20th, the Vernal Equinox. After that date
the sun will rise and set progressively further north until the Summer solstice in June.

The moon will also show us its monthly cycle of changes. The moon was full on March 1st and
will slowly wan until March 15th, the new moon. During this time the moon will only be visible in
the daytime sky to the right or west of the sun. After March 18th the waxing moon will be visible
in the evening sky. As it journeys across the sky, the moon will pass in close conjunction to
each of the 3 visible planets. The waxing crescent moon will pass Venus on the 17th. The
waxing gibbous moon will pass Mars on the evening of the 24th, and the nearly full moon will
pass Saturn on the evening of the 28th.

Just as the seasons go through cycles, we also see the sky go through cycles. As the Earth
rotates we see a cycle of day and night. As the moon revolves around the Earth we see its
cycle of phases. As the planets revolve around the sun we see them slowly change their
position among the constellations. And as the Earth revolves around the sun we see the
constellations change and the other celestial objects perform the dance that has captivated
humans for thousands of years. While March may not be the ideal month to get out with a
telescope, it is a great time to get outside and observe the changing season.

Rod Kennedy is a technician at the Casper Planetarium. He can be reached at 307-577-0310 or rodk@tribcsp.com.

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