Bad Astronomy: the Moon

I seem to spot bad astronomy everywhere these days. The Guardian's Life section, last Thursday, is the latest culprit. They had an article about Antartica which came with a day in the life of a scientist. Under the entry for 2am David Adam states:

"The sun can no longer be seen, but it has merely dipped behind a mountain, not set below the horizon. The only real clue that this is the dead of night is that the moon is just about visible."

Once again the bad astronomy is in the propagation of a misconception. In this case the misconception is that, just like in children's story books, the Moon only comes up at night. This is just not the case as it can be quite possible to see the Moon during the day.

It is at this point that I am suddenly reminded of one lunchtime at school when I was about 9 years old. I was standing in the playground looking at a radio mast in the distance. It was a cloudless day and shifting my gaze upwards I was surprised that I could quite clearly see the Moon. This was quite a shock at the time as I had grown up with the notion that the moon was to be associated with the night.

The Moon has a 28 day orbit around the Earth and follows a course across the sky similar to the Sun. Now the Sun appears to go around the Earth once a day (this is actually the Earth spinning on its axis) so we can see that they go out of sync. At first quarter the Moon is high in the sky during the evening, at full moon it rises to its highest point by around midnight and at last quarter it can be seen in the early morning. At new moon, the Moon is pretty near the Sun so will be up around midday. From the point of view of an observer, the Moon spends roughly half its time up during the day and half at night. If it was never up during the day we would never get an eclipse! Perhaps everyone should stick to using stars to represent night rather than the moon.

Posted in astro blog by Stuart on Monday 19th Jan 2004 (00:30 UTC) | Permalink
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