Don’t you ever find yourself looking at the vast expanse of the night sky with one question resurging over and over again? A question which is not uniquely yours or mine, a question which has been asked and thought of from the beginning of times: “Are we truly alone in the universe?” Well, luckily, that’s just astrobiology’s role, to find answers to various questions regarding the universe’s origin, living conditions, extraterrestrial life.
Astrobiology also called, exobiology or xenobiology, is a scientific subfield of astronomy that focuses on exploring the possibility of life existing elsewhere in the universe. This captivating, complex field combines knowledge from astronomy, biology, geology and chemistry to investigate the origins, evolution and distribution of life in the cosmos. But astrobiology doesn’t only study distant planets and other celestial bodies, it also seeks to answer questions about the survival of life in extreme environments. This also includes our planet, which can vary from deserts with temperatures of blistering heights to polar regions with frigid temperatures. In this article we’re going to cover some of the most intriguing questions:
How did life originate on Earth?
One word: abiogenesis. This term refers to the process by which life emerged from non-living matter, the appearance of living organisms from inanimate substances in the absence of pre-existing life. It is believed that life on Earth appeared around 3.5 to 4 billion years ago from simple organic molecules. Although there isn’t a 100% right answer on how this might’ve occurred, there are several theories which appear to come close to the truth. One important hypothesis is that of the “RNA world” which states that RNA (ribonucleic acid), similar to DNA, had a crucial part in the appearance of life. This molecule has important functions, such as storing genetic information and catalyzing chemical reactions, making researchers believe that it could’ve been the first self-replicating molecule. This might have eventually given rise to the first living cell. Another theory is that life originated in hydrothermal vents on the ocean floor. The heat, minerals and chemical gradients of those could provide the necessary conditions for the synthesis of organic molecules and the appearance of early life forms. Panspermia is another hypothesis which suggests that life originated outside our planet, somewhere in the solar system and may have been transported to Earth by asteroids, comets or interstellar dust. This idea suggests that life may be a cosmic phenomenon which could spread between planets.
Do other forms of life exist?
This is one of the most captivating and difficult question to answer as there is currently no evidence of extraterrestrial life. Astrobiology has long been trying to unravel the truth behind this question but has yet to succeed. The vastness of the universe and the diversity of celestial bodies makes the possibility of outer life tantalizing, but scientists continue to try to bring the truth to light. One way of finding out if life could exist outside Earth is searching habitable environments beyond our planet which could host other forms of life. Astronomers look for exoplanets (planets orbiting stars outside our solar system) which are in the “habitable zone”, where conditions are favorable and liquid water can be found.
In the past years, the development of technology has allowed astronomers to detect many exoplanets with similar characteristics to those of Earth’s. It is true though that many of them are inhospitable gas or ice giants with extreme temperatures or conditions, but there are also some which lie in the habitable zone of their stars, raising hopes that life could exist outside of Earth.
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