What’s Up in the Sky – November, 2010
By Peter Burkey
The connections people have to astronomy vary widely and are sometimes very subtle or even unknown. Recently a friend noted that he often scans the weather page in the newspaper, noting the times the Sun and Moon rise and set. Occasionally he notices that either the Moonrise or Moonset is listed as “none”. “How can that be?”, he asked. “Doesn’t the Moon rise and set every day?” We all got a chuckle out of “none”.
But it got me thinking. Sometimes newspapers make mistakes. Maybe the feed to the Naval Observatory was down that day. But it was always moonrise or -set, never sunrise. And I knew I should be able to answer his question but, I must confess, it took GVSU Professor Douglas Furton and a Google search to jar my memory.
The fact is that there actually are days when the Moon does not rise (or set). The reason has to do with the time between successive risings or settings. You probably know that the Sun sets a few minutes earlier or later (depending on the season) each day. But the Moon sets, on average, fifty minutes later each day.
The reason is because the Moon orbits the Earth in the same direction as the Earth turns on its axis so at the same time on successive nights it appears to move from west to east in the sky. This means the Earth has to make a little more than one rotation before the Moon sets again and this takes a little more than 24 hours.
And, because the Moon orbits the Earth, it can, and does, rise and set at all hours of the day. So, suppose the Moon sets at 11:45 p.m. on Monday. The following night it may set 45 minutes later, for example, at 12:30 a.m. which will be Wednesday, so the Moon did not set on Tuesday. About two weeks later the same situation holds for Moonrise.
So, a basic knowledge of some fundamental principals in astronomy is needed to understand some obscure entry on the weather page. But that is just one example of the many things in our world that can be understood through science. From what makes the stars shine to how far away the galaxies are, science enables us to answer many questions about what’s up in the sky.
This month in history:
Nov. 3: The dog Laika is first living creature to orbit Earth, aboard Sputnik 2 – 1957
Nov. 9: Carl Sagan born. – 1934
Nov. 16: Interstellar message broadcast from Arecibo radio telescope – 1974
Nov. 19: Second lunar landing made by Apollo 12 – 1969
Nov. 30: Ten-pound meteorite strikes and bruises Alabama woman, Elizabeth Hodges – 1954
Here are this month’s viewing highlights:
Planets this month: Jupiter continues to dominate the southern sky all night. Venus and Saturn are in the ESE before dawn.
Nov. 6: New Moon
Nov. 13: First-quarter Moon
Nov. 17,18: Peak of Leonid meteor shower, best before dawn.
Nov. 21: Full Moon
Nov. 28: Last-quarter Moon