It all depends on the conditions which exist on a potentially habitable planet. On planets covered with vast oceans life can exist in the form of water creatures resembling inhabitants of our marine environments. In a world with strong gravity and dense atmosphere large, strong and most likely aggressive (due to the harsh conditions of life) creatures may be present. In icy worlds, perhaps only bacteria can potentially exist. To survive, they may be forming giant networks.
This term is a result of the assumption that alien life, if it exists, must resemble Earth’s life forms. In particular, that is that basic molecules responsible for the metabolic chemical processes of life are represented primarily by carbon. It is apparent that this form of life is the closest to us, therefore it is extremely difficult for earthlings to imagine a different kind of biochemistry. We will not attempt to change these traditional views.
“Carbon chauvinism” limits our imagination about other forms of life, but, of course, does not prevent us from saying that earth-like life forms do not exist somewhere else in the universe.
Aurelia and Blue Moon
This is a joint project of the television Blue Wave Productions Ltd. and a team consisting of American and British scientists working together on a project sponsored by the National Geographic Channel. Aurelia and Blue Moon represent hypothetical examples of a planet and its moon, which could be home to extraterrestrial life.
The scientists suggest that planets like Aurelia can be discovered in about 10 years. It is highly likely that this planet will revolve around a red dwarf star. After all, these stars are the most common (80% of all stars) and are relatively close (50 light years away) to Earth (to detect planets at greater distances we would need to use more powerful telescopes which are not yet possible to build). Red dwarfs are cooler stars, they produce less than a tenth of the light coming from our sun.
So, we have a red dwarf. Around it, we have a revolving planet similar to Earth called Aurelia. In order for liquid water, an indispensable attribute of carbon life form to exist on its surface, the planet must be located close enough to its star, even much closer than our planet. A red dwarf, as we know, is much cooler than the Sun. Therefore, under strong gravitational force, this planet will not rotate around its axis and will always be turned with one side toward its host star. Thus, it will not be able to provide changes from day to night or seasonal changes.
It was previously believed that planets revolving around red dwarfs cannot have life forms present, because one half of the planet would have the atmosphere frozen, and the other half would have the atmosphere evaporated.
But using terrestrial weather model, scientists from the Met Office (UK National Weather Service) showed that liquid water can exist on a planet which does not revolve around its axis and located near the red dwarf.
The dark half of Aurelia is not lit, and the temperature cannot rise above zero. These are very unfavorable conditions for life to exist. The lit half of the planet according to the weather models has a permanent giant cyclone. Hurricanes and torrential rains occur without stopping. However, it could be that an area with warmer and stable climate can exist between the dark and the stormy sides of the planet. Here, according to the scientists, life is more than possible.
Rivers formed in the stormy zone, would flow in this direction, so there is a huge amount of water reservoirs. What kind of life forms can be present here?
If we assume that the approximate age of hypothetical Aurelia is 5 billion years, then it can be home to the following forms of life. Chief among them are Sting Fans. These bizarre creatures resemble plants, but they are actually animals that have learned to catch the daylight. They are fighting for a place under the sun, the red dwarf. Their planet cannot rotate, so the fans move by themselves in search for a better position. Sting fans reach 10 m in height. Their wings stretch towards the sun to get the energy for the production of sugar. Their simple in design hearts transport nutrients through the body. You do not believe they can? Think of similar life forms on Earth: corals, jellyfish, and some types of shellfish. They also live using other life forms; their captives carry out photosynthesis and produce the necessary energy. This is called symbiosis.
According to the world’s leading biologists and biomechanics specialists, Aurelia life will depend on Sting Fans. But there are other forms of life. For example, Cynodon species, the largest predator on the planet. Cynodon grows 4.5 m tall and weighs as much as a buffalo. Cynodon species completely resemble animals in their body structure.
Scientists who participated in the project suggest that “Aurelian” creatures most likely follow the laws of biology, similar to the earth creatures. Thus, it is logical for an Aurelian life form to have five senses and corresponding organs: eyes, ears, nose, skin and taste sensors. All these organs must be situated on the frontal part of the body, because the environment is perceived by animals from the front. It is also common for these creatures to have the brain or some type of a computing centre located as close as possible to the sensors. Long neck would allow the body to remain motionless while this part of the body will move, hunting for prey. Intestines take up a lot of space, but they must be contained in a stable location, at the feet, for example. Legs must be long enough to quickly chase the prey.
Living beings on Earth have chosen the same means of adaptation. There are not too many ways to swim or to move, and living creatures in the course of millions of years have adopted similar ways to move. According to scientists, it is probably going to be similar on other planets. The same process of evolution would create life forms on Aurelia.
The second hypothetical object of the study by leading experts is Blue Moon. It is a fictional natural satellite of Jupiter-type planets, almost completely covered by water and with a very dense atmosphere. These conditions allow scientists to suggest the presence of flying creatures comparable in size to a whale on this satellite.
Blue Moon should be comparable in size to Earth, but according to the model, its surface atmospheric pressure is three times greater than on Earth. A characteristic feature related to the Moon is the absence of polar ice caps. Dense atmosphere and ocean surface reduce temperature fluctuations.
Excess oxygen in the atmosphere should theoretically lead to an increase in muscle strength of flying whales with a wingspan reaching 10 meters. Billions of floating algae and mosses are floating in this “air”. They are the food source for the flying whales.
Non-carbon life forms
The most likely candidate for the role of structure-building atom according to alternative biochemistry is silicon. It has properties similar to those of carbon. But silicon atoms have greater mass and radius, and they form double or triple covalent bond in a more complex way. This may prevent the formation of biopolymers (polymers comprising the organisms). And although the main hypothesis regarding the existence of non-carbon extraterrestrial life is based on silicon, this life will probably have much fewer varieties than carbon life. This is because silicon compounds may not be as diverse as carbon compounds. But if this is so, then the silicon life form can be very different from familiar to us life forms, thus we hardly have the opportunity to speculate what “silicon” alien life forms may look like.