Other forms of life outside Earth?
From children fantasy books to prolonged research on the most controversial yet enthralling topic, let's see what real scientific evidence offers on this topic.
Disclamer: All things stated in this article contains professional views with evidences; the article itself does not contain the author’s personal viewpoints. A bibliography of sources is at the end of the article. Happy reading!
Aliens are always seen as green creatures, with an colossal head, dark big doe eyes; but after all extra-terrestial life may not fit in this specified description, maybe it is somewhat less than this or more than this.
Just as an introduction our milky way is just one of the billions of galaxies in the universe, our sun is just one of the 100 billion stars in the universe. As in this article, the term “light years” will be used, so first let’s clear the confusion on this term.
A light-time is the distance light travels within a specific period of time. One light second is equal to about 186,000 miles or 300,000 kilometers.One light-minute is 11,160,000 miles or 18,000,000 kilometers. One light-hour is approximately 671 million miles or 1.08 billion kilometers. One light day is 16.1 billion miles or 25.9 billion kilometers. One light year is 5.8 trillion miles or 9.4 trillion kilometers. 100 light years is a distance of 588 trillion miles or 946 trillion kilometers.
Britain’s first astronaut, Helen Sharman, believes that there is big possibility that aliens exist and probably they are living among us on Earth but have gone undetected so far.
There are so many billions of stars out there in the universe that there must be all sorts of different forms of life. Will they be like you and me, made up of carbon and nitrogen? Maybe not
Sharman was a chemist who spent eight days as a researcher o the space missionwhen she was 27, which makes her one of the youngest to enter the orbit. With such a vast and perpetual universe, Sharman believes in the possibility of life present on other bodies, or any extra-terrestial life itself present on Earth.
However, she is not the only one to speculate that we have had brushes with the aliens. A former Pentagon official who led a secret government program to research potential UFOs, revealed in 2017, told CNN at the time that he believes there is evidence of life reaching Earth.
In the NASA ask a scientist episode 5, NASA astrobiology expert, Dr Lindsay Hays says that this question has always been an interesting question, yet there is still no profound evidence that aliens do exist, she states:
“But if we think about life on this planet, beyond the big things — the elephants, the whales, redwoods trees –– and focus on the tiny things, nearly everywhere on Earth that we've looked, we've found microbial life.
Our definition of habitable environments continues to expand. Off the Earth we've only begun to look. NASA has sent five rovers and four landers to the surface of Mars. Additionally, orbiters have been outfitted with some amazing cameras to take pictures of the whole surface of the Red Planet. But we've only explored a tiny fraction of Mars. And that's only one of the promising bodies to look for life in our solar system.
There are icy moons in the outer solar system like Saturn’s moon Enceladus and Jupiter’s moon Europa that look like they may have subsurface oceans that could be habitable. And that's just what's in our solar system. The more exoplanets we find around other stars, the more we learn about how many different environments could exist for life.
We can't yet say for sure whether or not aliens exist. To quote Carl Sagan: “The universe is a pretty big place. If it's just us, it seems like an awful waste of space.” So, NASA will keep looking.”
Start with the number of stars in our galaxy, which is conservatively estimated at 100 billion, though is often cited as three times that. Of those 100 billion, from 20% to 50% probably harbor planetary systems—an estimate that becomes more and more reliable as the Kepler Space Telescope and various ground-based observatories detect increasing numbers of exoplanets.
Not all of those exoplanets would be capable of sustaining Earth-like life, so the equation assumes from 1 to 5 in any system could. Of those bio-friendly worlds, from 0% to 100% would actually go on to develop life. And of those world, in turn, from 0% to 100% would develop life forms that we would consider intelligent.
The mere existence of intelligent life forms tells us nothing, however, unless they have the ability to make themselves known—which means to manipulate radio waves and other forms of electromagnetic signaling.
The Milky Way has around 100 billion (1011) star systems that could conceivably host intelligent life under our current assumptions. An estimate of 100,000 (105) active civilizations in the galaxy would mean one per million star systems. At the exponential rate of growth in signal processing, researchers will have examined one million candidates by around 2034, bringing the odds of a discovery into the probable. Adding or removing a zero from the estimate of the number of civilizations out there merely adds or subtracts six years from the estimate, respectively, since that’s how long it takes to expand our search proportionally. See you in 2040, aliens. (Times)
Summary of the Times article: There are many galaxies and stars in the universe, the more signs we will receive of any life, the close we will get to find them.
If we say the world “life”, we not only refer to the intelligent forms of life but microorganisms as well.
Astrobiologists were a-twitter with anticipation and skepticism in September when news broke of potential evidence of life in the upper clouds of Venus. The announcement pointed to the presence of phosphine, a rare and often poisonous gas that, on Earth at least, is almost always associated with living organisms. With its hellish surface temperature, outlandish pressure and sulfuric-acid clouds, Venus has long played second fiddle to the seemingly more potentially habitable Mars. But a team aimed both the James Clerk Maxwell Telescope in Hawaii and the Atacama Large Millimetre/submillimetre Array in Chile at Venus and picked up phosphine's signature in a Venusian cloud layer with downright Earth-like temperatures and pressures. Terrestrial bacteria are known to thrive in some pretty tough conditions, making the biological explanation a not unreasonable one. The research team doesn't claim that it is airtight evidence of space bugs, and many in the community aren't quite convinced, but if nothing else it will mean more funding in the hunt for life in unlikely places.
With 300 billion stars in the Milky Way, many with solar systems, and ten billion years or more in which a civilisation could have arisen in this galaxy, it is difficult to believe that no lifeform ever reached the point where it could travel across interstellar distances. As the great Italian physicist Enrico Fermi said, it’s hard to explain why aliens haven’t made it to Earth. But there are ways of explaining why this hasn’t happened, says Maggie: “Our biggest problem is we only have one example of life, and that’s life on this planet.”
We have to think outside the box. For example, she says, “If you live by a star which is quite active, you might live below the ground… It doesn’t mean that intelligent life isn’t out there but you might not have the means of transmitting because you live below the surface.”
We are able to measure the atmospheres of these exoplanets using a technique called spectroscopy. This is where starlight passes through the atmosphere of the exoplanet, allowing us to do a chemical analysis. If we detect the kind of substances we find in Earth’s atmosphere, it wouldn’t necessarily confirm that there’s life out there – but it’s a strong indication that it’s possible. “We know of hundreds of potentially habitable planets,” says Professor Tim O’Brien. “We’re almost certainly – within the next decade or so – going to find a planet that may well even show potential evidence for life.”
When we’re contemplating the existence of life beyond our planet, it’s worth considering that we’ve discovered microbes inhabiting spaces on Earth where the idea of survival was previously inconceivable. These lifeforms are based on familiar DNA – so it’s life as we know it – but they exist in the deep trenches of our oceans, far away from sunlight. In the past, we believed life could only exist on a planet, a certain distance from its local star (so it has the right levels of radiation). Finding life on Earth thriving where we didn’t think it possible has opened our eyes to the concept that there might be moons able to support life too.
As soon as big telescopes like the one at Jodrell Bank Observatory were built, scientists realised that if there was a civilisation out there with a similar bit of technology, we might be able to pick up signals sent from one to the other. “We’ve now used radio telescopes to listen out for signals from extra-terrestrial civilisations since about 1960,” says Tim who is Director of Jodrell Bank. However, there are so many different ways in which a lifeform might send signals, we could spend our lives looking for them and get nowhere. It’s possible that we just haven’t hit upon the right method.
As well as method of communication, distance poses a huge obstacle. For a new project called Breakthrough Listen, scientists are searching a million of the nearest stars, but they’re also looking at stars that are in the middle of our Milky Way, 25,000 light years away. A message sent from one of these stars would need to travel in the region of 25,000 years before it even reached us. If alien life is out there, it could take thousands of years before we hear a peep from it.
Even if lifeforms with technology far more advanced than our own exist, they have to want to make contact. Any aliens out there may feel apathetic about us Earthlings! And they may not be overly keen on the idea of travelling between the stars for thousands of years in order to get up close and personal. This could also explain why we’ve never had extraterrestrial visitations – they’re simply happy where they are.
Thank you for reading!
Bibilography:
Overview | Beyond Our Solar System – NASA Solar System Exploration
Aliens definitely exist and they could be living among us on Earth, says astronaut Helen Sharman | CNN
Do Aliens Exist? We Asked a NASA Scientist: Episode 5 | NASA
Are Aliens Real? Is There Life on Other Planets? (time.com)
Extraterrestrial evidence: 10 incredible findings about aliens from 2020 | Live Science
BBC Radio 4 - The Infinite Monkey Cage - 10 reasons why aliens probably exist (but won’t be visiting us anytime soon)