We do not have direct evidence that there is life on other planets and in interstellar space. And yet, there are some convincing reasons to believe that one day we may find life even in our own solar system.
Here are seven reasons why it is worthy to believe that life exists somewhere else and is waiting for us to find it.
1. Theory of evolution
It states that life adapts to environmental conditions. Though Darwin hardly thought about life on other planets when creating his theory of evolution, he argued that in a place habitable for life it will certainly
take root. So if to think that our environment is not only our planet, but other planets and star systems, as well as interstellar space, an unusual interpretation of the theory of evolution can be made:maybe life can adapt even to the open space. Maybe, one day we will meet up with really unimaginable living beings.
2. The mystery of the origin of life on Earth
Although there is a recognized theory about the origin of life on Earth, there is a mystery of how carbon molecules came to form fragile membranes, which eventually became cells. The more we learn about a hostile environment that existed on Earth when life was emerging and developing, the more questions arise about the origin of life. According to the panspermia theory, single-celled life could have been brought to Earth by meteorites from somewhere else.
3. Variety and persistence of life on Earth
It is a fact that life on earth evolved in extremely difficult conditions, having survived ice ages, meteorite impacts, powerful volcanic eruptions, droughts, etc. Moreover, life on our planet has become very diverse in a relatively short period of time. Why would not the same thing happen on another planet in our solar system, or even in another star system?
4. Extremophiles on Earth
Extremophiles are organisms that can survive in the extreme conditions of cold, heat, exposure to toxic chemicals, and even in the vacuum. These creatures can live in sub-glacial lakes in the Arctic or in the hot volcanic vents. Tardigrades, amazing tiny organisms, can survive even in the vacuum. Thus we see that life can exist in such a hostile environment on Earth, therefore it can also exist on planets radically different from Earth.
5. Rapidly increasing number of Earth-like planets
In the last decade, a great number of planets outside the solar system were discovered, many of which are gas giants like Jupiter. However, technological advantages have allowed scientists to find smaller, solid planets like Earth. Moreover, some of them are in the so-called “habitable zone”, i.e. at such a distance from their star that they approach the terrestrial temperatures. Given the great number of planets outside our solar system, there is a probability that there are forms of life on one of them.
6. Existence of starting materials on other planets
It is believed that life on Earth began from chemical reactions that led to the formation of cell membrane and DNA. However, these chemical reactions could have begun from complex organic compounds, such as proteins, nucleic acids, etc. There is evidence that such substances already exist on other planets. For example, they were found in Titan’s atmosphere and in the environment of the Orion Nebula. Of course, this does not mean that there is life, but, according to many scientists, these substances contributed to the development of life on Earth. If they are common throughout the universe, it is likely that life emerged in other places too.
7. Oceans and lakes are very common in our solar system
Life on Earth emerged in the ocean, so it could happen in the same way on other planets. There is proof that once there was water on Mars and on Titan, one of the Saturn’s moons. It is also believed that once there was a big ocean on Jupiter’s moon Europa, covered with a thick ice layer. In each of these planets there could be life, and maybe there still is.