Moon does not rise or set!

[telecasterguru (Frank)]

Sometimes in the Moon Phase box on the left of this site it says that the moon does not rise or the moon does not set. How can this be?

Frank

[Mike21 (Michael)]

Frank, I think this is because the Moon rose before midnight and therefore did not rise on the day in question OR it set after midnight and therefore does not set on the day in question. It has to rise and set every day but not necessarily in that order, that is, it may set in the morning and rise again that afternoon.

[telecasterguru (Frank)]

I'm still not sure I understand, the moon rises at 6.30 tonight and sets at 7.00 tomorrow.

[Outbackmanyep]

Hi Telecasterguru,
The days start at midnight or 00:00 and end at 23:59. Lets use the 12th and 13th August for example.
The moon rises on the 12th August at 23:24 and sets at 09:22.
So on the 12th august the moon sets in the morning and then RISES again on the 12th at 23:54. BUT the 13th of August the moon SETS in the morning 09:57 and the moon doesnt rise until 00:29 on the 14th. SO the moon doesnt RISE at all on the 13th of August!

So that why they say DNR on the 13th!

[Robh (Rob)]

Frank,

Because of the axial tilt of the Earth, the time difference between sunrise and sunset in Sydney can vary anywhere from about 10 hours in winter to 14 hours in summer. The Sun rises and sets everyday and is highest in the sky at midday.
The Moon follows roughly the same path as the Sun across the sky but moves in the opposite direction at about 13 degrees per day relative to the background stars. This means the Moon rises and sets an average of about 52 minutes later each day (13/360x24hours). So from moonrise to moonrise is roughly 25 hours and from moonset to moonset is roughly 25 hours. As there are more than 25 days each month, this means there has to be at least one day each month when the Moon does not rise on that day. For example, on Aug 12th moonrise is 11:24pm but next moonrise is Aug 14th at 12:29am about 25 hours later. The same applies to moonset. On Aug 26th moonset is 11:59pm but next moonset is Aug 28th at 12:58am about 25 hours later. Interestingly, the time difference between moonrise and moonset can vary anywhere from about 10 hours to 15 hours.

Regards, Rob

[mojo (Terry)]

Originally Posted by telecasterguru

I'm still not sure I understand, the moon rises at 6.30 tonight and sets at 7.00 tomorrow.

The rise/set times are always for the day in question. It doesn't display yesterday or tomorrow. So if you're looking at the sidebox on the left, they are the times for today only.

The rise and set times will always be displayed showing the rise time first and the set time second. Which doesn't necessarily mean that the moon always rises first and then sets on any given day.

For today, it sets first in the morning at 7:37am and then rises in the evening at 6:51pm.

It happens for all the reasons mentioned in the previous posts

[telecasterguru (Frank)]

Thanks for the explanation and now I understand.

Frank