There are times when the sun goes down and it takes a while for the moon to rise, because the moon obviously doesn't rise with the sunset whole year. I guess this happens only when the moon is full. Also, in some days, moon sets in the midnight and there is no moon on the sky for the rest of the night. So, I was wondering what that time period of the night is called when the moon has gone down, or has yet to rise? Can we call it 'moondown'? I am not talking about the new moon when there is no moon the whole night. Please help, and thank you in advance!
$\begingroup$ Dark of the moon: merriam-webster.com/dictionary/dark%20of%20the%20moon $\endgroup$– Wayfaring StrangerMar 8, 2017 at 14:09
1$\begingroup$ It's not quite what you're going for, but in observational astronomy the two weeks between third quarter and first quarter are called "dark time" since the moon is up less than half the night. You might colloquially use "dark time" to refer to the hours before the moon rises or after the moon has set. By contrast "bright time" refers to the weeks between first and third quarter. $\endgroup$– J. O'Brien AntogniniApr 6, 2017 at 22:58
You are right that the moon only rises as the sun sets when it is full. At other times there is some time each night when both the moon and the sun are both set.
The terms moonrise and moonset are well established, by analogy with sunrise and sunset. The time when the moon is at its highest point in the sky is known as lunar culmination. You can use "lunar day" for the 24.84 hour period between lunar culminations. I know of no specific term for the period when the moon is set, or for when it is risen, instead you can say "after moonrise" or "before moonset", as appropriate.
$\begingroup$ I've come across the very poetic description of a dark night as "blacker than the earl of hell's waistcoat", but that's not a term used in astronomy ;-) $\endgroup$– launeMar 7, 2017 at 22:04