# Tag Info

## Hot answers tagged day-night

72

It really bugs them What you've probably misunderstood is what the term "Java developer" actually denotes. Java developers are a small mammal similar to civet cats in Indonesia both in physical characteristics and how they are used by humans. They remove bugs from and consume carefully managed Java beans, passing out the undigested remainder into the soil ...

61

People are curious Humans, at least, are very curious. Shamans on spirit journeys, young men on adventures, and outcast groups in exile might all end up traveling into the night zone for one reason or another. And if they had not seen stars before, they would be amazed, and behold them with wonder. Once word got out of these stars, many of the religious ...

57

Terrain objects I imagine these nomads are following the same paths every year as they perpetually circle the planet. In that case, since there are no seasons or months, each group's time cycle would be based around terrain objects they pass. This is the month of the Blue Woods, next month is the Snow-capped Peaks, next month is Dust Plains, etc. Once ...

39

If they're avoiding both the heat of the day and the cold of the night then there are dawn and dusk people. Most likely you have four main groups, two who move constantly and two who move and settle for long periods. The dawn tribe will move until they start seeing stars, then it's time to settle until the heat of the day catches up with them. The evening ...

34

Something to do wth circadian rhythm. I'd use circads. Alternatively, something to do with biological oscillations. Alternatively, something to do with blood pressure (or other medical metric) that has a twenty four hour cycle. But I'd personally recommend coining the term 'circad.'

33

Total Eclipse I know this isn't directly an answer to your question, but the novelette Nightfall by Isaac Asimov deals with a civilization living on a planet in a system with six suns which keep the whole planet continuously illuminated. The people have no actual awareness of any stars beyond their local solar system, as they cannot see them and they are ...

33

For Months/Seasons: The terrain. Presumably they will be in the same place every nine years, and they know where they are relative to the cycle. You'd get the Month of the Great Salt Lake and so forth. This would divide your "years" into "months" For Days/Hours: Water Clocks or Hourglasses. Even on a moving cart (I'm not sure how fast the people are ...

27

If an entire race of sapient creatures are moving, they need to take their animals, clothes, tools, houses with them. Their settlements are nomadic caravans, and the few times they get ahead of the dawn/dusk line is when they circle up and rest. They also need to carry their supplies with them. It means having tank carts with water to cross a desert/arid ...

27

On a planet with a 9-year day/night cycle, some plants will adapt to that cycle. They will lay down roots in the day cycle, and then die off for four and a half years, only to spring back to life when the sun comes back. Just look at how any plant copes with a cold winter environment (trees lose leaves, perenials die to the root and grow back from a bulb, ...

26

It's entirely possible. Have you ever had your eyes dilated at the doctor's office? It makes your pupils very large because the muscles to contract them are temporarily paralyzed. If you go outside without some pretty dark sunglasses you can't open your eyes because it's so painful due to being far too bright, however, seeing in low light is no problem. If ...

24

Visual Discovery in Dark Areas If your scenario allows for people to venture into dark areas where stars are visible to the naked eye, then certainly that will be the easiest way for people to discover stars. Non-Visible Light Astronomy If your scenario requires people to stay in areas where stars are not visible to the naked eye, then techniques other ...

23

The poles provide the ability to stay on either side safely. Since the planet has a relatively small axial tilt (13 degrees), the North and South poles of this planet shouldn't be incredibly cold relative to the rest of the world. They would be inhabited, just like the rest of the "belt" that spans the planet. Observers at the either pole could (somewhat) ...

20

Your inhabitants could be following big herds of animals, migrating in the same way they do. If the animals are big, you basically have familiar clans joining to hunt them. Soon, they snatch a few baby animals (perhaps after watching for several "awake cycles" which mother is less aggresive) and tame them. This requires time and patience, but with more ...

19

There are two types of cells in mammalian eyes - rods and cones. Rods are long photoreceptor cells that are highly sensitive to light, and are of use primarily in night vision, yet we have only one type of rod cell (that is maximally sensitive to blue-green light), hence we can only see in shades of that colour, which we interpret as grey. However, when ...

18

NASA does already face this problem with its Mars rovers (since both visibility and power from solar panels require daylight): https://en.wikipedia.org/wiki/Timekeeping_on_Mars Full sunrise-to-sunrise cycle is called Martian solar day, or "sol" for short. Since it is only 40 minutes longer than Earth day, they have sol divided into 24 Martian hours, and ...

16

Does/can the planet have a moon? If it had several small fast moons like Mars, then that's a perfect external reference point. For instance, Phobos has an 8 hour orbit, and Deimos has a 30 hour orbit. So on the 9 year planet one orbit of Moon 1 is one time unit (say an hour), and an orbit of Moon 2 is a Day. Or whatever. It would be a little like the hands ...

15

If we put aside the "mythology" on the flat earth believer of ancient times, we can see that the awareness of the planet being round was well spread even before circumnavigation was possible: Eratosthenes calculated the globe's diameter when just crossing the Mediterranean was a challenge, and did this based on purely astronomical evidence (the shadow in the ...

15

Decrease the brightness of your moon, and make it invisible during the day. By making the surface of your moon darker, you reduce its brightness due to light reflection (albedo). Cover it with black lava fields or dark stones. If it's dark enough, your moon should be only visible during the night or twilight. You can give your moon the same apparent ...

15

A graphical method Sometimes a graphical method may be easier to understand and remember. One year is the time required for the planet to complete one full orbit around its primary. You decide how long a year is; it could be shorter than an Earth year, it could be longer; but if the star is similar to our Sun, and the planet is supposed to be habitable for ...

14

In addition to the three good answers so far received, the people of your planet would almost certainly be able to see certain astronomical objects by daylight. On Earth even in daytime we can regularly see with the naked eye the moon, obviously, plus several planets, some meteors and comets, and supernovae when they occur. It is true that one cannot ...

14

The earliest civilizations started in great river valleys, like Sumer (Mesopotamia), Egypt (Nile), China (Yangtze) and India (Ganges). This was because the land near the rivers was easy to irrigate and became fertile for crops. People settled down and abandoned the hunter-gatherer culture when they started to harvest crops. This is called the agricultural ...

14

Actually, I'd argue the opposite; it would be unfortunate in the long term (in geological scales) for life if the length of a day wasn't lengthening. The primary reason why the length of the day is increasing is because of Tidal Friction, which is caused by the moon. The moon is also getting gradually further away from the earth, and will one day leave ...

13

To stay in the light, groups would farm collectively With a 9 year day/night cycle, a single group would not be able to settle down and farm a plot of land for more than a few days. Living near the equator, on an Earth-sized planet, with an Earth-length year, the nomads would need to cover an average of 7 miles/day. If they can travel 21 miles in a day of ...

13

You need smoke. Or dust, or volcanic ash. The haze will make it dark and gloomy and if you do it right, the suspended particles will make the sun seem small and blue via the Rayleigh effect . Photo by Jan Smith: Blue sun during Brisbane dust storm https://volcanocafe.wordpress.com/2015/01/24/once-in-a-blue-moon/ Particles of size around 1 micron ...

12

Actually, an 48 hour cycle is great, because it's exactly twice the normal 24 hour cycle. Thus adaption would be easy; people would just sleep twice for each planetary day. There might, however, be the need to have bright enough illumination during the "night-day" time, in order to stay healthy for a prolonged time (I guess they are on that planet for the ...

12

TLDR: It wouldn't be a problem for creatures that are native to that world. Things that evolved in a place like that wouldn't need darkness to sleep. Humans and other diurnal creatures on Earth have sleep cycles that are regulated by light levels (mainly the hormone Melatonin) in order to encourage us to sleep when it's dark and be awake when it's light ...

11

I do not believe life could evolve under such conditions but I see no reason to think the world would need to be lifeless. Plants. There are two survival options here: We have a very common class of plant that needs little tweaking to survive this. We call them annuals. They live during the warm time, produce seeds and die. Those seeds bring about the ...

10

Yes, this is possible on Earth, but you will not be able to breathe. The Earth's axial tilt of 23.5 degrees means that at winter solstice, the pole will be 23.5 degrees tilted away from the solar terminator. This converts to a distance of $$\frac{23.5}{360}*40075\text{ km}=2616\text{ km}$$ Trigonometry can be used to calculate the minimum height one has ...

10

I have one major point to make: A good portion of Jupiter does not complete one rotation in 9.8 hours. Jupiter isn't like a giant ball of rock. It's called as "gas giant" for a reason, which is that it has a large, massive, turbulent atmosphere that's constantly moving and changing. This means that its atmosphere undergoes differential rotation, a ...

10

Give your planet a mega-ocean. Water is a great heat transfer mechanism. On Earth, we have currents that run from equator to pole, and significantly warm places like the UK. If you created a world with many small islands you could have an almost earth-like setup but a very slow period of rotation. Your currents will most likely go east-west rather than ...

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