by William J. Bechaver
HUERFANO- This month there will be another close encounter between the moon and the planet, Mars. This time, the encounter will appear high in the sky because the moon will be in the first-quarter phase.
The encounter will happen tomorrow evening, Fri. March 14. The moon and Mars will be closest to each other around ten o’clock. Look high in the western sky and notice the separation will be less than 1 degree between the moon and the planet (which appears as a bright red "star")! That’s an amazingly close coupling this time around.
If you will recall, during their close encounter in December, the planet was at opposition, and the moon was full during the passage. This month the moon will be just past the first-quarter phase; it won’t be full for another week. So, for a little extra hands-on scientific observation, try this to see how quickly Mars moves across the sky. After locating Mars near the moon, keep an eye on it for the next week. It will remain relatively stationary in the sky for that period of time. Then go out and find the full moon on March 21st. Observing where the moon is full on that night gives some indication of where Mars was located in December. Observing the distance between the full moon and Mars at its current location gives a rough sense of just how far Mars has traveled in three months — a quarter of the way around the sky in about a quarter of the year.
So, in addition to being an interesting sight in the night sky, this month’s pairing of Mars with the moon also provides opportunity for basic astronomical observation. It is by just such rudimentary observations that the ancient Egyptians were able to calculate the passage of time and the changes in the night sky so accurately, to the point that they could predict when such conjunctions would occur years in advance of the event. However, they only devised truly accurate means of observation after many years of continued observation, sometimes by several different ancient astronomers over many lifetimes.
An observer must keep in mind that the earth is also in motion. So our observation can only determine how far Mars has moved in relation to our position in space. Too complex, even for the Egyptians. For even though they could predict and calculate these movements, they had no clear idea why such movements occurred. In their minds, the Earth was stationary and at the center of the solar system and no amount of observational data could reconcile in their minds the strange movements of the planets.