SciFi Q of the Day: Lunar Day and Night

MoonSciFi Question of the Day: If the lunar colonists use GMT for their clocks, yet the patterns of darkness and light last for a couple of Earth-weeks each, what will the words “Day” and “Night” refer to? What other words might they need?

Facebook Answers

  William J. Teegarden What do “day shift” and “night shift” mean on a starship? What do day and night mean inside the arctic and antarctic circles? Same deal.  

  Eric Schmitt Second Breakfast.  

  Perry Willis They will still have to maintain a basic day and unleas they operate 24/7 they would have 2 or 3 shifts. As for the sunlight, the would have lunar day and lunar night. But these would only be important for things happening on the surface.  


  Eric Schmitt perhaps you should ask submarine crews what they are doing….

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  .  Clint Johnson  .

I’m building my colony in a lava tube and will just cycle the lighting to match Terran time.

Anyone got a spare $2 billion?… hey, didn’t +Eric Schmidt just get the okay to liquidate a bit of Google stock?

  .  AmyBeth Inverness  Have you tried kickstarter?

  .  Jacob Merrill  Or—– don’t sleep cycles happen, just don’t mess with them,

lights can effect mood, but dimming the light can be dangerous…..

  .  Ismael Muniz  .  Perhaps they will call it the same as here on earth except add moon to the word. Moon-day, Moon-Friday, Moon-Double cheese burger. LOL


Paul Carr  I

 would expect we would adopt practices used by Antarctic scientists who have six months of sunlight then six months of darkness.  The sun can’t be depended on to regulate body clock.

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Chris Lyons  .  

Its more than just a day/night. If you used say a 24 hour clock (which would make more sense to me) you could work around a “normal” rest/work cycle. However, the length of a “day” is dependent on location. There is a small region (only a few hundred yards across on the lunar “south” pole and the top of a crater ridge on the lunar “north” pole) that receives sunlight 24/7. Except of course when the moon passes through the earth’s shadow. These two spots are also current candidates for lunar colonies as they also have perpetual line-of-sight with the earth (for communications). While working indoors it would be easy enough to adjust light level to let the during the “evening” to let the body know its getting close to rest time.The real question is time. Our “time” is based on the rotation of the earth. This account for our 24 hour clock. This is also is the reason we have 60 seconds in minute. This is important because we measure frequency (like a radio wave or the speed of a computer chip) in oscillations per second.Without proper timing, computers on earth would not be able to talk to computers on the moon. So any “clocks” that did not conform to our set 24 hour cycle would have be controlled by a computer that was still timed off of an earth clock, be mechanical and designed specifically for the area in question or be controlled with a wholly new type of computer timing system.

I work with a satellites as my primary job, and timing ground stations so the computers can talk to each other can be a pain in the rump.

  AmyBeth Inverness  But… the moon is tidally locked, so the same face is always towards Earth. Doesn’t that mean that half the moon’s surface is in perpetual line-of-sight with Earth?

  Chris Lyons  Yes, but not perpetually in direct sun light for solar power. Powering a station with no atmosphere and no sun for weeks on end with no sunlight is something Nasa is still working on and why Thorium reactors have been so discussed lately.

  AmyBeth Inverness  Aha! It all becomes clear!

  Chris Lyons  Time is a construct … physics and engineering people can’t even agree on what time is. Some theories call it (time) its own dimension. The real question is, how far down the rabbit hole is a writer willing to take his/her reader?

  Brett Slocum  Humans need a schedule approximately 24 hours in cycle. Otherwise they go crazy. So, the Lunar Colony #1 will set clocks on a 24-hour schedule, regardless of what’s going on outside. But they’ll have their own time zone.

  Chris Lyons  True. Getting back to the original question, I don’t see how it would be any different than living in, say, Barrow, Alaska where the sun goes down for 65 days a year staring around November 18 or 19th. Any other time of year and the sun is up.

  Francene Stanley  Days of Illumination – and – Darkest Days.

  Zachary Besterfield  They would likely be living in pressurized habitats carved deep into the rock. Warrens of tunnels and small caverns would be sealed from the vacuum of space, and sunlight. So my guess is the darkness would be a technical issue for solar energy production and the like; the average colonists might never be concerned with the surface darkness unless unless there was a loss or rationing of solar power. So, not only would they use GMT, but their circadian rhythm would be set to the original mission control location back on Earth.

  Chris Lyons  +chris vighagen I am sorry you are offended, however you should also keep in mind the setting for the topic. This is not a pure science group. This is not a physics research group. This is not a sleep disorder or micro-biology group. You are also not the only person on the planet, the internet, or even this group with a sleep disorder.If you are offended by this conversation, report it. If you do not wish to be part of it, then don’t be.Yes, this is a Sci-Fi group for writers of the genre. Yes, there are a lot of people here who are not scientists (imagine that), nor should they be. However, please do not (virtually) throw your hands up and say things like, “I dont do rampant speculations that has no base in science.” It is rude.

  Susan Benedict  Just remember … Diversity is good. Sometimes speculation creates the science and sometimes the science creates the speculation. There is a place for both of them, really. Now that I think about it, they are so dependent on eacth other that we would have gotten no where if they had not gone hand in hand. Just sayin’

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Doug Grayson .

While Lunar time would likely derive from GMT, I think it would simply default to the twenty-four hour military time cycle.  “AM” and “PM” would be “groundside” terms, not ones for the Loonies.


James Gormley .

Isn’t the far side of the Moon always dark (not illuminated by the Sun)?


AmyBeth Inverness .

No. The same face of the moon always faces EARTH. The moon does have day and night cycles, but they are about 27-28 days, thus daylight lasts for a couple weeks, then darkness lasts for a couple of weeks on any given stationary point.But I did have to look that up and double and triple check to make sure I got it right…


James Gormley .

I see, but what is the far side illuminated by, stars?


AmyBeth Inverness .

I’d have to ask +michael interbartolo about just how much ambient light the far stars provide, but I don’t think it’s very much at all. Definitely dark.


Burrows Goldhawk .

Since they would rarely go outside, day and night would be artificial, and most likely correspond to their home country, not UTC.


Francis Horton .

Wouldn’t lunar colonists be presumably living underground anyway? I imagine “The Moon is a Harsh Mistress” would be a much more likely situation when it comes to lunar living. If so, it really wouldn’t matter since you aren’t living by a sun cycle.


Dale R. Gowin

+James Gormley  . Solar system geometry 101: The “far side” of the moon faces away from Earth, not from the sun. The moon orbits around Earth, and both, locked together, orbit the sun. The sun is stationary relative to the Earth/moon system. The “far side” of the moon is lighted when the moon’s orbit takes it between Earth and sun; it is dark when it is on the “far side” of Earth.


Jon Southurst .

Of course, when there’s a solar eclipse, the ‘dark side’ of the moon must be facing the sun. And many other times besides.

As for time, they’d probably just have a local time that is referenced to the time in other places on Earth, just like we do now. A couple of clocks on the wall would do it.


James Gormley

+Dale R. Gowin  . Courtesy 101: I knew that it faced away from the Earth, so please don’t assume others have a kindergarten understanding of basic astronomy. My understanding is that the far side is called the dark side because it is dark from our perspective and does not, only again from Earth’s perspective, receive the light that the illuminated side of the moon receives via indirect sunlight reflected from the Earth. And certainly the moon is illuminated by the sun at each full moon once a month, does receive light on different hemispheres during each quarter, and does rotate and pass between the Earth and Sun during new moon.Yes, we do know this.


Dale R. Gowin .

No offense intended. I’m a kindergarten kid compared to some of the folks in here.

  .  James Gormley .  No sweat……I love astronomy, but more from a sense of wonder and appreciation for its beauty and awesomeness than from anything else.



Dale R. Gowin .

The back of the moon would be a great place for an observatory.


James Gormley .

True, I seem to remember reading that telescopes there would not have to deal with the radio transmissions/interference from Earth…..

  .Burrows Goldhawk  +Dale R. Gowin  . The back side of the Moon would be a great place for radio telescopes since the Moon would eliminate any noise from the Earth, which is very, very noisy in the radio spectrum.


Day and Night might only become a reference to a person’s mood. “You are as bright as day today” or “you are dark as night.”

Instead of “Day” and “Night” the words might change to “Up” and “Down”. In reference to being awake and moving around (Up Time) or lying down and sleeping (Down Time).

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I would imagine that there would be a need to create a unified system abandoning the day/night convention. As long as colonization doesn’t extend to the interstellar, solar cycles may be employed. It would be beneficial in that some times in the cycle are characterized by heightened solar winds, indicating a time in which travel may be somewhat more perilous.You could wind up with various seasons and breakdowns of time that make up the whole 11 year cycle, or say, 1 Sol.Edit: I just noticed we’re talking just lunar here. In that case, yeah, just stick with standard earth metrics.


They probaly just have lunar timezones


There would be no reason to change much from convention at a distance as near as Earth’s moon. Use of Earth timezones is more than likely what will be utilized regardless of lunar light/dark cycles.


I think I would prefer to keep a 24-hour system. I would just get used to night lasting for weeks and days lasting as long. I would tell myself it was like living in Alaska. I don’t think I’d want to abandon one of the main constants in my life, though.


Yep agree with the above. They would still need to communicate and need to know what time it was on earth. The light cycles of the moon would be purely academic.


They will become separate from the time of day.


it would all be relative to time, not if it is dark or not?


Most of colony life on Moon would take place indoor anyway. For confort of the colonists, animals and plants, I guess it’ll be artifical day & night anyway. Mimicking GMT day and night ?


Since time and clocks are essentially a faulty man-made convention, it wouldn’t matter much in the long run how you set it up. Biological reaction to natural light cycles would likely override anyway, unless you isolated the colonists from the external cycle.


Dan Thompson .

I think they’d stick with the Earth conventions, and day and night would continue to refer to the colonists wake/sleep cycles.  I suspect they would have different terms for whether the surface was illuminated or not, perhaps “suntop” and “darktop”.


Day and night are referenced to location and the rotation of planet / orb. Exposure to the sun regardless of length would equate to a day. Lack of exposure to the sun would equate a night. So in order to use GMT, lunar colonists would need to mathematically adjust time.

Just as you do not physically lose or gain a day on earth when you cross….

Google Plus Answers: Public Post

  Geof Fantastico  What do those that live far north refer to “day” and “night” when it is dark all day or bright all night?  I assume that they use the same terms, but I do not know.
  Joel James  simple:is this bi-polar?
  Andy Brokaw  I see them keeping day and night, but having other words for sleep time and awake time. (This would also help Earth do away with all those silly timezones, which will only get sillier as transportation becomes faster, and switch the whole planet onto GMT as well.) Conversely, they could keep current usage but refer to it being light or dark, but I like the first way because it allows everyone to use standard time.
  Jonathan Black  They’ll most likely be living underground at first unless the 3D printed option works. It would be easy to set the lights on a day/night cycle.

Samuel Falvo II

We are already referring to days and nights on other planets.  Since the Mars rovers are solar powered, for example, it’s important for NASA to keep track of which Martian day it is.  Also, the winter and summer seasons on Mars don’t line up with those on Earth, but are important for xenometeorology studies on the planet.

I rather suspect that the lunar colonists will refer to lunar days and earth days with appropriate qualification, as we currently do today with Mars.

SciFi Q of the Day plus comment

About AmyBeth Inverness

A writer by birth, a redhead by choice.
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1 Response to SciFi Q of the Day: Lunar Day and Night

  1. More questions:
    How to get water from the moon’s polar ice caps to the equator where the elevators would be.
    The dork side of the moon… 🙂
    How does LIVING on the moon affect a werewolf?

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