Get Regular Updates!
Search
|These are the places that (most likely) host alien life

Space

image|

Danielle Futselaar / SETI Institute

These are the places that (most likely) host alien life

These are the places that (most likely) host alien life

Not too cold, not too hot—the conditions for life are found not just on Earth, but on a handful of other places out in the universe.

These are the places that (most likely) host alien life

We Earthlings are a really lucky bunch. Our planet is located in just the right spot in our Solar System. We’re not too close to the Sun, like Mercury or Venus, where the average temperature can reach more than 400°C. It’s not too far away, either, like Jupiter or Saturn, where it can get really cold—way under 140°C.

But our planet is not the only one with such ideal conditions. A bunch of other planets and moons are also found in the so-called habitable zone or Goldilocks zone. Planets or moons located in the Goldilocks zone are at the right distance from their star so that they’re not too hot and not too cold—just like Baby Bear’s porridge in the fairy tale. Their overall temperature is just right for the formation of liquid water, a landmark of life.

Of course, it is not just about being “in the zone”. Mars, for example, is found within the habitable zone of our system, and we have yet to find the first Martians.

Also, being in the habitable zone doesn’t mean they actually have water, but they could. These potentially habitable planets need to meet other requirements to be able to host some sort of life, like having an atmosphere, being a rocky planet (and not one made up of gas) and having the right mix of chemical compounds needed by living organisms.

View Larger
Image|NASA
A comparison of the habitable zone of our solar system with the Kepler-22 system

Is there life out there?

This question has been in the mind of people for aeons, and maybe now we are finally close to getting an answer. Several celestial bodies, either planets or their moons, have been identified as potential candidates to host life.

Some are planets around the same size of Earth, orbiting a star much like our own Sun. Others are called super-Earth planets and are as large as 45 times the size of Earth.

In the search for life on other planets, the most famous candidate, arguably, is Mars, which made some big news recently when it was confirmed it hosts a vast amount of water just beneath its surface. The finding, according to experts, means that Mars could one day allow for the establishment of a human colony and perhaps even allow some other lifeforms to exist.

“Certainly on Earth, we find life associated with big ice sheets. So it doesn’t actually have to be liquid water in which life can exist, and it would be very interesting to look at where these ice scarps are melting,” Simon George, at Macquarie University, said.

“[The melting ice could] potentially expose new bits of ice and possibly be a very interesting place to look for new evidence of life, either in the recent geological past or even living today on Mars,” George added in a recent news report.

Video|Beyond Science
Water ice discovered beneath Mars surface

Beyond Mars, another place where scientists are pouring their hopes are the moons from a big planet.

Life on a moon

Saturn, one of the largest planets of our solar system, has 62 moons, some of which are tiny moonlets just 1km in diameter. Others are larger than some planets, like the moon Titan, nearly half the size of Earth.

One of Saturn’s moons has been the focus of attention among extraterrestrial life hunters: Enceladus. Here, scientists have discovered vast oceans of water, buried 30 to 40 kilometres beneath the moon’s surface, which is covered in ice and snow and where temperatures reach -198°C, at noon! The Cassini space probe revealed the existence of all the vital ingredients for life in these oceans: carbon, nitrogen and hydrogen.

“I think this is it. From an astrobiology point of view, this is the most interesting story,” said Chris McKay, a planetary scientist at NASA in a recent news report.

Saturn is not the only planet with a moon that potentially hosts life. Jupiter’s moon Europa has been a target for exploration since the 1960s.

View Larger
Image|NASA
Jupiter’s moon Europa could potentially host life

Made famous by the book (and movie) 2001: A Space Odyssey, Europa has an ocean of liquid water lurking beneath a layer of ice 15 to 20 kilometres deep. At least two future NASA projects plan to explore this moon in more detail.

Europa Clipper and Juice, both planned to launch some time in 2020, will make detailed studies of the surface of Jupiter and three of its moons, Ganymede, Callisto and Europa.

Life beyond our Solar System

Other stellar systems that host potentially habitable planets have been identified in the past years.

Just last year, a study reported the existence of a possible super-Earth planet, about 41 light years away from Earth. The planet, named LHS 1140b, is 1.4 times the size of Earth and twice as dense and is found within the habitable zone of its star system.

“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics in a press release.

“We could hardly hope for a better target to perform one of the biggest quests in science—searching for evidence of life beyond Earth.”

However, nothing yet is known about the inner components of this planet.

“Right now, we’re just making educated guesses about the content of this planet’s atmosphere,” said Jason.

“Future observations might enable us to detect the atmosphere of a potentially habitable planet for the first time. We plan to search for water, and, ultimately, molecular oxygen.”

View Larger
Image|M. WEISS/CFA
An artist’s impression of LHS 1140b and its host star

The planet 1140b was discovered through the MEarth project, which seeks to identify Earth-like planets. Besides 1140b, the MEarth project has so far discovered two other Earth-like planets, GJ1132b, and GJ1214b.

Another stellar system that has revealed the existence of potentially habitable planets is called TRAPPIST-1. The system, 39 light years from our planet, is located in the constellation Aquarius, and recent observations have revealed the existence of at least seven small planets orbiting the central star of this system. Out of these seven, three planets are found in the habitable zone.

“This is an amazing planetary system, not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!” said Michaël Gillon, at the University of Liège in Belgium, who led the 2016 study, in a press release.

Two of these planets, TRAPPIST-1b and TRAPPIST-1c, were further studied and are likely to be rocky planets, like Earth, which makes them even better candidates for hosting life.

Other potentially habitable planets have been identified by NASA’s Kepler space telescope. One of these planets, Kepler-452b, is located in the constellation Cygnus, with a star very similar to our own sun. The planet is about 60% larger than Earth, but whether it is a rocky planet or if it contains liquid water is still a mystery.

“We can think of Kepler-452b as an older, bigger cousin to Earth, providing an opportunity to understand and reflect upon Earth’s evolving environment,” said Jon Jenkins, from NASA’s Ames Research Center, in an official press release.

“It’s awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star; longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet,” he added.

Image|

NASA/JPL-CALTECH

The Kepler Project discovered many planets in the habitable zone with similarities to Earth, as outlined in the line up above

The Kepler Project discovered many planets in the habitable zone with similarities to Earth, as outlined in the line up above

Life as we know it

But how do you really know if a planet can host some sort of life? Until you actually find some alien life form, it is all really theoretical. But now, a new study just published found solid evidence that one species of microorganism could survive in Saturn’s moon Enceladus.

The compounds found in Enceladus, such as methane, carbon dioxide, ammonia and hydrogen, can be either produced or used for growth by microorganisms.

In this new study, researchers managed to grow microorganisms under the gas and pressure conditions thought to be present in Enceladus. Researchers found one survivor: a microorganism capable, in theory, of surviving in Enceladus, even under the presence of nasty compounds that would inhibit the growth of other life.

“The microorganism Methanothermococcus okinawensis thrives and produces methane under conditions similar to those found in Saturn’s icy moon Enceladus,” says Simon Rittmann, at the University of Vienna, who led the new study.

Furthermore, researchers identified a geological process known as serpentinisation, which might produce enough hydrogen for the survival of some kind of lifeform on Enceladus.

View Larger
Image|NASA/JPL-Caltech
Interior of Enceladus, showing it’s liquid water ocean

The findings support the idea that certain microorganisms can thrive in Enceladus and be responsible for some of the methane detected in this moon.

But will we ever find some sort of intelligent life? Some scientists think so, and the reason is simple: odds are on our side, sort of.

It is a big, big universe with trillions of planets and stars, and we already know many moons and planets very like Earth have the right conditions for life as we know it. So why not?

“In the search for life in the Solar System and beyond, the physiological capabilities of several organisms found on Earth that live or survive under extreme environmental conditions make it likely that, somewhere in the universe, alien life could exist . It could be possible that we might find life just a doorstep away,” says Simon.

Natural evolution VIDEO

Republish

Creative Commons Logo

Republishing our content

We want our stories to be shared and seen by as many people as possible.

Therefore, unless it says otherwise, copyright on the stories on Particle belongs to Scitech and they are published under a Creative Commons Attribution-NoDerivatives 4.0 International License.

This allows you to republish our articles online or in print for free. You just need to credit us and link to us, and you can’t edit our material or sell it separately.

Using the ‘republish’ button on our website is the easiest way to meet our guidelines.

Guidelines

You cannot edit the article.

When republishing, you have to credit our authors, ideally in the byline. You have to credit Particle with a link back to the original publication on Particle.

If you’re republishing online, you must use our pageview counter, link to us and include links from our story. Our page view counter is a small pixel-ping (invisible to the eye) that allows us to know when our content is republished. It’s a condition of our guidelines that you include our counter. If you use the ‘republish’ then you’ll capture our page counter.

If you’re republishing in print, please email us to let us so we know about it (we get very proud to see our work republished) and you must include the Particle logo next to the credits. Download logo here.

If you wish to republish all our stories, please contact us directly to discuss this opportunity.

Images

Most of the images used on Particle are copyright of the photographer who made them.

It is your responsibility to confirm that you’re licensed to republish images in our articles.

Video

All Particle videos can be accessed through YouTube under the Standard YouTube Licence.

The Standard YouTube licence

  1. This licence is ‘All Rights Reserved’, granting provisions for YouTube to display the content, and YouTube’s visitors to stream the content. This means that the content may be streamed from YouTube but specifically forbids downloading, adaptation, and redistribution, except where otherwise licensed. When uploading your content to YouTube it will automatically use the Standard YouTube licence. You can check this by clicking on Advanced Settings and looking at the dropdown box ‘License and rights ownership’.
  2. When a user is uploading a video he has license options that he can choose from. The first option is “standard YouTube License” which means that you grant the broadcasting rights to YouTube. This essentially means that your video can only be accessed from YouTube for watching purpose and cannot be reproduced or distributed in any other form without your consent.

Contact

For more information about using our content, email us: particle@scitech.org.au

Copy this HTML into your CMS
Press Ctrl+C to copy

We've got chemistry. Want something physical?