A study hypothesizes that extraterrestrial beings might emit red, blue, or green light as a means of self-protection.
Although often depicted as small green beings or towering monsters in films, experts suggest that aliens are unlikely to resemble these portrayals. Instead, the unique environments of their home planets and moons may lead to appearances that are entirely different from anything found on Earth.
Common depiction of extraterrestrials. (Photo: Guardian).
Some extraterrestrials may evolve to traverse the skies of their planets due to thick atmospheres, according to Adam Frank, an astrophysicist at the University of Rochester, who spoke to Live Science. In cases where a planet has high gravity, aliens might develop robust body shapes similar to elephants.
Valentina Erastova, a chemistry researcher at the University of Edinburgh, does not rule out the possibility that life could evolve to exist underground. If a planet experiences high levels of radiation not absorbed by an ozone layer, subterranean life could use soil to protect its body. In this scenario, Erastova speculates that multicellular life may resemble fungi. While we often see the mushroom stems growing above ground, much of its life occurs below in a vast network of roots known as mycorrhizae.
In cases of intense ultraviolet (UV) radiation, a study published in the journal Monthly Notices of the Royal Astronomical Society in 2019 indicated that extraterrestrials might emit red, blue, or green light as a form of self-defense. Similar to corals, these organisms could possess proteins or pigments that help absorb some energy from ultraviolet light, causing them to glow at safer wavelengths within the visible spectrum.
According to Frank, another potential adaptation is that extraterrestrials may have very slow metabolisms due to the frigid environments of their worlds. Titan, Saturn’s largest moon, serves as a good example of a very cold world that could host life forms in methane seas. Sloths on Earth exemplify animals with extremely slow metabolisms, operating at only 40-45% the metabolic rate of other animals of similar size, resulting in very leisurely movements.
Researchers even suggest that extraterrestrial life might be much simpler than luminous organisms, flying beings, or fungi. “It is more likely that life on other worlds will be unicellular,” speculated Sarah Rugheimer, an assistant professor of astronomy and astrophysics at York University in Toronto. “For most of Earth’s history, the only form of life that existed was bacteria. Even today, bacteria comprise the majority of the biosphere.”
Detecting unicellular life from Earth could be a challenging task, but scientists suggest addressing this issue by examining the evidence of life left behind by bacteria. In a 2019 study published in the journal Astrobiology, researchers noted that calcium carbonate deposits found in dry hot springs could be the result of extraterrestrial microbial mats. Searching for such deposits on other planets may reveal fossilized bacterial sources.
According to Rugheimer, if extraterrestrial life evolves into multicellular organisms, the likelihood of them resembling humans is very low. Our form is a result of evolution in Earth’s unique environment. However, extraterrestrial life might possess some similar traits due to convergent evolution, such as eyes for observing the environment, limbs or wings for movement. Of course, all these ideas are based on the assumption that extraterrestrial life would require essential conditions similar to those on Earth, such as water, sunlight, and oxygen to survive.
