While there is the possibility of life existing in ways that we haven\u2019t even imagined, there are a few things that life as we know it cannot thrive without. Our searches for extra-terrestrial life have therefore focused on looking for the following elements:<\/p>\n
- \n
- A source of energy<\/li>\n
- Liquid water<\/li>\n
- A stable environment<\/li>\n
- A temperature conducive to life<\/li>\n
- Biogenic elements, such as oxygen, carbon, hydrogen, and nitrogen.<\/li>\n<\/ul>\n
Ten Places in our Solar System That Could Support Life<\/span><\/h2>\n
<\/h3>\n
Europa<\/span><\/h3>\n
![\"Europa](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Europa_-_September_1997_16411900725.jpg\" "\\"Europa_-_September_1997_(16411900725)\\"")
Kevin Gill from Nashua, NH, United States<\/a>, CC BY-SA 2.0<\/a>, via Wikimedia Commons<\/p><\/figure> Kevin Gill from Nashua, NH, United States<\/a>, CC BY-SA 2.0<\/a>, via Wikimedia Commons<\/p><\/div>\n
Europa is the smallest of Jupiter\u2019s famous Galilean moons<\/a> and the sixth-largest known moon in our Solar System. Its surface famously features a thick water ice crust, which astronomers believe covers a deep ocean that encompasses the entire moon. Due to tidal friction and heating<\/a>, this ocean may only be slightly cooler than oceans here on Earth, leading some scientists to consider Europa as one of the strongest candidates for life elsewhere in our Solar System.<\/p>\n
Ganymede<\/span><\/h3>\n
![\"Ganymede](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Ganymede.jpg\" "\\"Ganymede\\"")
<\/p>\nWith a radius around 600 miles bigger than our Moon<\/a>, Ganymede is the largest moon in our Solar System. Like Europa, Ganymede features an internal ocean. However, Ganymede may contain more water<\/a> than all of the oceans on Earth combined. Computer models have determined that Ganymede\u2019s ocean could feature rocky sea bottoms \u2013 and scientists believe that the contact and interaction between rock and water could be a key mechanism in the development of life.<\/p>\n
Io<\/span><\/h3>\n
![\"The](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Io.jpg\" "\\"Io\\"")
<\/p>\nIo<\/a> might be a moon, but it\u2019s also the most volcanically active world in our Solar System, with violent volcanoes, lava flows, and lakes of lava. It\u2019s also the closest Galilean moon to Jupiter, meaning it receives some pretty intense radiation. Io might not sound like somewhere that will go to the top of your list of holiday destinations, but beneath the fiery surface, water could exist in underground chambers that provide a great location for life to thrive, even if it\u2019s only microbial life. With its intense volcanic activity, Io also has plenty of lava tubes, which geologists have found to play host to microbes in Iceland<\/a>.<\/p>\n
Callisto<\/span><\/h3>\n
![\"Despite](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Callisto_diagram.jpg\" "\\"Callisto_diagram\\"")
Kelvinsong<\/a>, CC BY-SA 3.0<\/a>, via Wikimedia Commons<\/p><\/figure> Kelvinsong<\/a>, CC BY-SA 3.0<\/a>, via Wikimedia Commons<\/p><\/div>\n
Rounding off the Galilean moons is Callisto, the second-largest of the four and the third-largest moon in our Solar System. Previously, astronomers considered Callisto a mundane object with no volcanic or tectonic activity. However, closer studies have revealed the presence of oxygen in the moon\u2019s thin atmosphere and a salty subsurface ocean that interacts with a rocky seabed, meaning that Callisto is another great Jovian candidate for life.<\/p>\n
Enceladus<\/span><\/h3>\n
![\"The](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Enceladus.jpg\" "\\"Enceladus\\"")
<\/p>\nEnceladus<\/a>, the sixth-largest moon of Saturn, is the most reflective and whitest object in our Solar System. More importantly, it also features a salty subsurface ocean heated by tidal forces. But it\u2019s another of the moon’s features that makes Enceladus a very tempting target for the search for extra-terrestrial life \u2013 powerful geysers<\/a> that shoot ocean water out into space. This means that probes can taste the water from Enceladus and work out more about the chemical composition of the ocean and, perhaps, even directly find the presence of microbial life.<\/p>\n
Titan<\/span><\/h3>\n
![\"Titan](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Saturn_and_Titan_-_May_22_2015_29951133920.jpg\" "\\"Saturn_and_Titan_-_May_22_2015_(29951133920)\\"")
Kevin Gill from Los Angeles, CA, United States<\/a>, CC BY 2.0<\/a>, via Wikimedia Commons<\/p><\/figure> Kevin Gill from Los Angeles, CA, United States<\/a>, CC BY 2.0<\/a>, via Wikimedia Commons<\/p><\/div>\n
Staying in the Saturn system, Titan<\/a> is the ringed planet\u2019s largest moon and the second-largest in our Solar System. It\u2019s also the only moon with a thick atmosphere<\/a> and the only body (other than Earth) to definitively have liquid running on its surface. Titan is known to have lakes, rivers, and a water cycle like our own, with evaporation and rainfall. However, Titan\u2019s surface liquid is actually composed of liquid gases<\/a>, such as methane and ethane, not water. That said, the Cassini-Huygens mission<\/a> revealed that the moon also likely has a subsurface ocean of salty liquid water. This ocean could make Titan a possible candidate host for both life as we know it and alternative life forms that might thrive in the moon\u2019s hydrocarbon liquid surface environment.<\/p>\n
Mars<\/span><\/h3>\n
![\"Mars,](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/mars-gf61ecde61_1920.jpg\" "\\"mars-gf61ecde61_1920\\"")
<\/p>\nIt\u2019s one of the oldest and most frequently asked questions in astronomy: is there life on Mars? Given the planet\u2019s proximity and similarities to Earth, it\u2019s long been a burning topic that has captured the imaginations of astronomers and non-astronomers alike, but what do we actually know about Martian habitability? Astronomers have known about the planet\u2019s polar ice caps for centuries. However, in 2018, Italian scientists discovered a large reservoir of liquid water<\/a> underneath the surface. Two years later, astronomers also found possible signs of current surface water<\/a> and detected methane in the Martian atmosphere \u2013 often a tell-tale sign of biological processes.<\/p>\n
Despite these possible clues, scientists still haven\u2019t found any direct evidence of life – so we still don\u2019t have an answer to give David Bowie<\/a>. However, there are possible clues that Mars WAS habitable at one point in its history<\/a>, with evidence of volcanic activity, lakes, oceans, rivers, and rainfall.<\/p>\n
Venus<\/span><\/h3>\n
![\"Whiule](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/venus-gdd4529944_1920.jpg\" "\\"venus-gdd4529944_1920\\"")
NASA\/JPL<\/a>, Public domain, via Wikimedia Commons<\/p><\/figure><\/p>\n
Venus<\/a>, the second-closest planet to the Sun, was named after the Roman goddess of love because astronomers thought the planet to be beautiful as they viewed it shining brightly in the night sky. It turns out that Venus is not<\/em> a very nice place unless you like thick, toxic atmospheres, sulphuric acid rain, and surface temperatures hot enough to melt lead! But despite this harsh environment, some scientists believe Venus was once surprisingly Earth-like. In fact, it could have been habitable until as recently as 700 million years ago<\/a>.<\/p>\n
While we might never know more about the previous habitability of Venus, there is still a chance that still life prevails today. While the planet\u2019s surface isn\u2019t friendly to life as we know it, clouds high up in the atmosphere<\/a> offer a far more tolerable environment, with nutrients, sunlight, possibly water, and more hospitable temperatures.<\/p>\n
Triton<\/span><\/h3>\n
![\"Neptune's](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/1024px-Neptun_und_Mond_Triton.jpg\" "\\"1024px-Neptun_und_Mond_Triton\\"")
Arndt Stelter<\/a>, CC BY-SA 4.0<\/a>, via Wikimedia Commons<\/p><\/figure> Arndt Stelter<\/a>, CC BY-SA 4.0<\/a>, via Wikimedia Commons<\/p><\/div>\n
Orbiting Neptune<\/a> at a distance of around 4.5 billion km from the Sun and one of the coldest objects in our Solar System<\/a>, the moon Triton<\/a> might not be the most obvious place in our Solar System that could support life. But Neptune\u2019s largest moon does tick a few boxes that have piqued the interest of astronomers. It\u2019s one of the few bodies in our Solar System known to be volcanically active, and scientists believe it also possesses a subsurface ocean heated by tidal heating.<\/p>\n
Ceres<\/span><\/h3>\n
![\"Formalls](\"https:\/\/osr.org\/wp-content\/uploads\/2023\/02\/Ceres.jpg\" "\\"Ceres\\"")
<\/p>\nAs a dwarf planet located in the main asteroid belt between Mars and Jupiter, Ceres<\/a> sounds like something of a long shot in the search for life. However, recent studies have found that the asteroid-turned-dwarf planet is geologically active<\/a> and is the second-most water-rich object<\/a> in the inner Solar System (after Earth). Any life that may exist on Ceres would likely be very primitive microbial organisms, but that\u2019s still better than the nothing we\u2019ve found so far!<\/p>\n
How Will We Search the Places in our Solar System That Could Support Life?<\/span><\/h2>\n
Scientists have been conducting searches for extra-terrestrial life for decades. Still, as more incredible tools become available, such as the James Webb Space Telescope<\/a> and transit spectroscopy<\/a>, we\u2019re discovering ever more tantalising clues that we might not be alone in the universe. But until we know more, why not learn more about some of the other fascinating objects in our galaxy? With the OSR\u2019s One Million Stars App<\/a>, you can take a tour through the cosmos and explore stars and constellations.<\/p>\n
![Kevin Gill from Nashua, NH, United States<\/a>,](\"https:\/\/commons.wikimedia.org\/wiki\/File:Europa_-_September_1997_(16411900725).jpg\"){kind=link}
![Kelvinsong<\/a>,](\"https:\/\/commons.wikimedia.org\/wiki\/File:Callisto_diagram.svg\"){kind=link}
![Kevin Gill from Los Angeles, CA, United States<\/a>,](\"https:\/\/commons.wikimedia.org\/wiki\/File:Saturn_%26_Titan_-_May_22_2015_(37198904334).png\"){kind=link}
![Kevin Gill from Los Angeles, CA, United States<\/a>,](\"https:\/\/commons.wikimedia.org\/wiki\/File:Saturn_and_Titan_-_May_22_2015_(29951133920).jpg\"){kind=link}
![Arndt Stelter<\/a>,](\"https:\/\/commons.wikimedia.org\/wiki\/File:Neptun_und_Mond_Triton.png\"){kind=link}