How would the astronomical clocks behave if there were beings on other planets, with a different day length, for example on Titan where the day lasted only 16 hours
A well-known phenomenon in the animal world is the connection between their activity or inactivity and sunlight. There are animals that are active during the day and on the other hand there are animals that are active at night. Similar phenomena of reactions to light and darkness also exist in the plant world. If we translate this phenomenon into astronomical terms, then it is the rotation of the earth around its axis that dictates the behavior of the animals and plants regarding some of the times of the desired activity. Are these peak activity hours the result of evolutionary processes or are they the result of environmental adaptations? It's hard to know. A question that mentions what came first, the egg or the chicken.
When examining the question of the existence of extraterrestrial life, this phenomenon must also be considered. This is because planets everywhere in the universe rotate around their axis and revolve around suns. Even if we consider the moons of planets, this topic is still valid. Although these moons show only one side of their face to the planets, this is a situation in which the length of their day is equal to the time they orbit the planets and therefore there are periods of time when the surface is illuminated by the sun and there are periods of time when the surface is dark, the length of the day is conditioned by the speed of the axial rotation of The planets and the moons. There are three known biological astronomical clocks on Earth which are defined by the length of their cycle. One clock is the short and basic cycle - this is the time in which the planet moves around its axis - the day, the medium cycle - this is the time in which the planet orbits the sun - the year and the long cycle - this is the time in which the planet orbits the sun for several years - this is the perennial cycle.
The short cycle
This cycle is the dominant cycle in animals and plants. In animals, since in their movement and in their search for food sources, they rely mainly on the sense of sight. Other senses, such as the sense of hearing and the sense of smell, contribute significantly to these needs, but without the sense of sight they would have difficulty functioning. Birds, for example, in their migratory journeys fly at high speeds and must rely on the light, so they are active during the day. At night vision is limited and sometimes impossible. Carnivorous animals in their pursuit of food sources use their eyes to locate available food. They must direct themselves well towards their victim and equally must direct their attack on the prey, so that they can sink their fangs into the neck of the animals being devoured. Without daylight they would have had a hard time doing that.
In the plant world, the photosynthetic processes occur only during the daytime, and react in different ways to light and darkness. "There are plants that fold their leaves for the night at the same time every evening in the evening... Many plants use their clocks to open and close their flowers at fixed times every day." As for growth, it gets certain characteristics for the night hours. "Plants grow in different forms in the dark and in the light. An expected response to the darkness is the gradual degeneration due to the lack of resources created in photosynthesis." Daytime activity can also be due to other reasons. Reptiles, for example, are cold-blooded and their bodies do not have mechanisms capable of regulating their body temperature. At night their bodies get cold and they become lethargic. It will therefore be more comfortable for them to operate during the day when it is warm in their habitat.
Another option is to move the activity to the hours of darkness, since daylight is a disturbing factor. This pattern of behavior can be found in amphibians such as frogs, toads and newts. During the day, the humidity drops and animal skin dries out. In order to avoid this, they hide during the day and only at night, when the air cools and becomes more humid, they gather their food.
A special type of nocturnal activity is associated with the moon. When the moon is in full display, the activity of saltwater fish and eels is greater, as the display of the moon decreases, their activity also decreases. Another pattern of behavior related to the fullness of the moon concerns the reproduction of animals: it is found at the equator. In this geographical area, the length of the day is equal to the length of the night almost throughout the year. The moon shows are of the utmost importance for determining the dates of reproduction. Black-headed gulls from the tropical Asuncion Islands return every year in the tenth month of the lunar calendar to these islands to build their nests.
The average time cycle
This cycle is of great significance in the animal world, since it determines the date of mating in many cases. This cycle has to do with the inclination of the earth's axis to the plane of the whip. As a result of this inclination the year is divided into two. In one part the days are getting longer and the nights are getting shorter in the northern hemisphere, and in the southern hemisphere the days are getting shorter and the nights are getting longer. This half of the year is summer in the northern hemisphere and winter in the southern hemisphere. In the second part of the year in the Northern Hemisphere the days are getting shorter. In this half of the year, it is winter in the northern hemisphere and summer in the southern hemisphere.
These changes in the number of hours of the day have a cardinal effect on the behavior of mammals. Among this group of animals, the pineal gland in the brain releases serotonin, and at night the serotonin is converted to melatonin, which integrates into the bloodstream.
This achieves several things:
1. Monitoring the biological clock - melatonin maintains sleep and wake cycles.
2. With the lengthening of the night, the rate of production of the hormones that change the appetite and the rate of metabolism is increased. There are animals that slow down their activity as the night lengthens. In bears, squirrels and badgers, with the arrival of winter, the heart rate and breathing slow down.
3. The changes in the length of the day (the length of the day affects the production of sex hormones) determine the time of mating - females must have a large amount of food to ensure their development and survival. Both at the level of the individual and at the level of the species. A large animal requires large amounts of food and a small animal requires smaller amounts of food. In any case, the birth takes place in the spring when growth is at its peak and insects are found in a very large quantity. The larger the animal, the mating time takes place closer to the beginning of winter - when the days are getting shorter, while for small animals, the mating time occurs later in the winter, with the lengthening of the daylight hours.
In plants, the number of hours of the day affects the formation of bulbs and the set of leaves. In the different seasons, many plants that bloom in the spring are sensitive to the shorter nights (these are long-day plants). Other plants that bloom in the fall are "in many cases plants that bloom following the developmental signal of longer and longer nights (these are short-day plants)". Long day plants are for example carnations, radishes, marjorams and clover and short day plants are for example chrysanthemums, corn and coffee bushes. However, it is worth noting that there are plants for which the number of daylight hours is not significant, such as sunflowers, tomatoes and potatoes.
Trees are not able to absorb water at the same rate as it evaporates and in order not to lose this precious water, the shedding is done in the fall. The signal for the start of shedding is the shortening of the daylight hours.
The long time cycle
This cycle spans several years. Each particular phenomenon repeats itself once every few years. In cicadas, for example, the number of years that pass between egg laying and the development of the complete adult is 13 or 17 years. The bamboo plants of the Himalayas bloom once every 50 years. What makes these plants special is that even if they are grown in places with topographical and climatic characteristics
Different, their flowering will still be once every 50 years. Wherever they are planted, they break down a very large amount of seeds. This process is not well understood. In any case, what is clear is that there is some kind of mechanism that performs the counting of years. Since the process is the same in different places, it is clear that this is not a cyclical local phenomenon but some sort of universal cycle observed in one of the "senses" of the bamboo. A counting mechanism probably also exists in the cicadas. Here the measurement is more complex since it is one of the two cycles subject to the "choice" of the cicada.
Bioastronomical derivatives
This diagnosis of the astronomical clock gives us a tool with which we can try to build an outlook regarding biological clocks on various stars. From our knowledge of the solar system in which we live, we know that there are planets and moons whose day is very long, or longer than the Earth's day, or very short - shorter than the Earth's day. The only planet whose day length is almost the same as Earth's is Mars. Callisto's day length is 16 terrestrial days, and Triton's is 5.8 days. Therefore, the longer the day, the animals have more hours of activity and the plants have more hours of photosynthesis. If we assume that other stars also have a wide variety of animals and that there are carnivorous animals and vegetarian animals, then the carnivorous animals will have more hours of activity throughout the day, in which they can search for their prey, and in a short day they will have fewer hours at their disposal. This may also have an effect on their running speed. If the day is longer, they can slow down their running pace, since they have a lot of time at their disposal. If the day is shorter they will have to be faster. This of course depends on the amount of time that passes from the moment they feel full to the moment when hunger arises again. It should be taken into account that their "fullness clock" is also adjusted throughout the day. An important factor to consider is a particularly long day. If the day is like on Triton for example, it is hard to believe that an animal will last a long time in earthly terms without eating. In these cases, it should be taken into account that the animal during its evolution sharpened other senses so that it could also hunt at night, such as infrared vision (in a framed article it is worth noting that bees also see in ultraviolet), a greater range of hearing and a developed sense of smell.
On Earth, reptiles are cold-blooded, at night they are almost inactive because they are unable to warm their bodies. One has to assume that crawling across stars with a day equal to or shorter than the day of the earth, their behavior will be similar. On the other hand, in stars with a long day, it is doubtful whether they will be able to exist for a long time without movement. There are two possibilities, either these stars will not have reptiles at all or they will be warm blooded. Amphibians vs. reptiles are inactive during the day due to the potential for their skin to dry out quickly, which would result in their death. For this reason, in stars with a day that is equal to or shorter than that of the Earth, their behavior will be similar to terrestrial amphibians in stars that have a long day. It is doubtful that they will be able to survive long without activity. The possibilities are then two, either that these stars will not have amphibians at all or that the humidity in these stars will be high enough for them to be able to operate even during the daytime.
As for the birds, in a very long day they have more daylight hours available to fly, but will they use all the hours of the long day? Can birds fly, for example tens or perhaps hundreds of hours without a break? She will need hours of rest, to gain strength and continue the flight. Will they stop flying when they feel tired or will they open an internal clock that tells them when to rest during the day?
As we have seen the biological clock can be conditioned by the existence of a moon. If a planet, for example, has no moons, the animals will not develop any lunar clock. It is possible that the same planet has several moons and then animals that behave according to different lunar clocks can exist next to each other. When these clocks are conditioned by the fullness of the moons or the color of the light reflected from them.
As for plants, the question that arises is how they behave in stars that have long days and the number of hours they are without photosynthesis is long and they may degenerate. Are the many hours of photosynthesis they receive during the day enough for them to get through the long night or have they developed additional energy sources that are activated during the hours of darkness? Another question is to what extent a long night will affect the characteristics of growth, and if these characteristics do exist, do they operate at certain hours of the night?
The lengthening of the day and the shortening of the night are a result of the inclination of the earth's axis. This principle is true for every planet and every moon wherever they are. The most well-known example is Mars. Most planets are oblique as well. What characterizes Mars is that its angle of inclination is the same as that of the Earth, therefore the lengthening of the day and the shortening of the night are equivalent to those occurring on the Earth. The only difference between the two planets for this matter is the length of the average cycle. Since Mars is farther from the Sun, its year is longer. Since the length of its year is 687 days compared to the 365 days of the creation of the earth, its seasons are twice as long. If a planet exists somewhere else in the universe, about the size of Mars, but with an atmosphere similar to that of the earth and if it has life as we know it, then also Among these animals, the same metabolic changes will occur, with the change of seasons, melatonin will maintain the sleep and wake cycles here as well. The obvious question here is whether the slowdown in activity in the winter will also be for such a long time. Since the year is longer, it can be assumed that the length of the year also has an effect on the mating time.
In such a long year, will the duration of pregnancy also be related to the length of the winter, with reference to the size of the animals, or will the length of the winter season also be related to this? That is, since the winter is very long, it is possible that the mating time even in large animals will be closer, with the lengthening of the daylight hours.
From these things the conclusion is required that the existence or non-existence of seasons depends on the inclination angle of the planet or the moon. If the axis of rotation of the star and/or the moon is perpendicular or almost perpendicular to the plane of motion, then there are actually no seasons. In this situation, the number of daytime hours as well as the number of nighttime hours does not change throughout the year and there will be no slowdown in the pace of activity.
As for mating times, the animals will develop other biological clocks. If the axis of rotation of the star is tilted, then the conclusion is required that as the axis is tilted at a greater angle with the onset of summer the number of hours of the day will increase and with the onset of winter the number of hours of the day will decrease. If we take two planets that are similar in size, but have different inclination angles, one with an inclination angle of 23.5 (like the Earth and Mars) and one with an inclination angle of 50, since the one with the greater inclination angle, its number of light hours will be greater than the one with the angle the smaller inclination. This will have more far-reaching effects on the biological clock and all that it implies. A special case is of planets whose inclination angle is 90, as in the case of Uranus and Pluto, in this case the day of the planet is equal to its year. The polar regions will be light and dark in an annual cycle and the equatorial region will be light all year round, although it will be a very weak light, which is similar to twilight light. Regarding the equator, the astronomical biological clocks will have no meaning, but regarding the other regions, especially the poles, it will have a great meaning. Since the day merges with the year, the biological clocks will have different shows than what we are familiar with on Earth.
As for the vegetation on declinated planets, it is certainly possible to refer to the existence of short-day plants and long-day plants, because if the planet or the moon are declinated, their year is also divided into two, a period in which the days are getting longer and a period in which the days are getting shorter, depending of course on which hemisphere the northern or the southern Planets and moons that do not have an inclination angle will not have this diagnosis of this vegetation for the reason that the number of hours of the day is equal to the number of hours of the night. Since the climate is the same throughout the year, they will have to develop unique biological clocks that will classify the time of leaf fall in terms of the long time cycle. Due to the rarity of the phenomenon on Earth (permanent climate Earth exists only in the equatorial region), it is difficult to know if it can be common or rare also on other planets and life-bearing moons. In any case, it can be said that if the star year is equivalent to, for example, 5 earthly years, then these are particularly long cycles.
Summary
Examining the biological clock shows that it is of the greatest importance for the existence of life on Earth, and as a result also on other stars. Its influence is felt in the behavior of animals, in the way their senses are activated following changes in the number of hours of the day and the number of hours of the night, in their metabolism and hormonal control. In the same way, the biological clock leaves its mark on the plant as well. You can feel it in the photosynthetic mechanisms in the ways of growth and when the leaves fall.
This complexity of the relationship between biological clocks and astronomical constellations of stars and lifestyles can be effectively tested with the help of computer simulations.
Comments
1. John Downer - The world of the senses The sensory perception in the living world, ed
Moden, 1991, p. 124
2. Zachs Zvi - The meaning of form in plants, broadcast university, ministry
Defense, 1989, p. 33
3. John Downer - ibid., p. 202
4. Ibid., p. 136
5. Ibid., p. 137
6. Ibid., p. 132
7. Ibid., p. 133
8. Zaks Zvi - ibid., p. 35
9. John Downer - ibid., p. 128
10. Ibid., p. 129
11. There, there.
12. Ibid., p. 140
13. Zaks Zvi - ibid., p. 37
14. Mazar Haim - "Day and night cycles in the solar system". All stars of light
1988 5-6עמ' .194-198
15. There, there.
