Are there aliens in Earth’s backyard yet? Incredible graphics reveal the moons in our solar system that may be hiding life
It’s one of the biggest unanswered questions in science: If there is life beyond Earth, where is it?
While you may think the answer is “far far away,” it could surprisingly be a lot closer to home than we thought.
Our own solar system is now home to nearly 300 moons – some of which could have the perfect conditions for life.
But which are the most promising candidates?
From Jupiter’s moon Europa to Saturn’s satellite Enceladus, this image shows which moons are most likely to harbor aliens.
Moons – also called ‘natural satellites’ – are defined as such when they orbit a planet. There are just under 300 known moons in our solar system, but the best candidates for life are Europa, Enceladus and Callisto
Scientists have just discovered three new moons around Uranus and Neptune. Pictured is the Uranian moon, provisionally called S/2023 U1. Uranus is just outside the field of view at the upper left, as evidenced by the increased scattered light
According to experts, one of the planets most likely to harbor life is Saturn’s moon Enceladus, which shoots plumes of water from a hidden liquid ocean.
Jupiter’s moon Europa has CO2 on its surface (on Earth, a byproduct of cell function), while Jupiter’s larger moon Callisto may have a salty ocean beneath its surface – a potential habitat for life.
Jupiter’s Ganymede – the solar system’s largest moon – is thought to have an interaction between water and rock, which is essential for the development of life.
And Neptune’s moon Triton is known to be geologically active and has an atmosphere composed largely of nitrogen, just like Earth’s.
Scientists recently revealed that they have found two more moons: one around Uranus and two around Neptune.
Amazingly, according to NASA, there are still “thousands” of moons in our solar system likely awaiting discovery.
Dr. Robert Massey, deputy director of the Royal Astronomical Society, agrees with NASA that there are many more moons we don’t know about.
But they are all probably much smaller than the above candidates – a few hundred or even tens of kilometers in diameter.
‘Undiscovered moons are likely to be around the giant planets – Jupiter, Saturn, Uranus and Neptune,’ Dr Massey told MailOnline.
‘But we can be sure that we have discovered all the larger moons in the solar system around other planets.
These images show the two newly found moons around Neptune – tentatively named S/2002 (left) and S/2021 N1 (right). S/2002 N5 (left) is slightly bright and therefore clear in the image, but with S/2021 N1 the moon is very faint. It can be seen roughly as a black point of light right in the center of the image. This one is very difficult to see because it is so faint: the faintest moon ever found on a planet
Pictured is Jupiter’s moon Europa, where an ocean hidden beneath miles of ice is considered a prime candidate for extraterrestrial life. Scientists have found carbon dioxide (CO2) on Europe’s surface and the next step is to determine where it comes from
‘Moons now discovered tend to be much smaller – no more than a few kilometers in diameter – and therefore much fainter. Larger and more sensitive telescopes are therefore required to find them.’
Last week, scientists discovered three new moons: two orbiting Neptune and one orbiting Uranus.
Dr. However, Massey thinks it is “extremely unlikely” that any of the three newly discovered moons are candidates for alien life because they are too small to have an atmosphere and are not thought to have subsurface oceans.
In general, the smaller the moon, the less likely it is to have life, because life requires an atmosphere.
Martin Hendry, professor at the University of Glasgow’s school of physics and astronomy, told MailOnline: ‘If a moon is too small, gravity isn’t strong enough to hold an atmosphere, so there’s nothing for life in it. to breathe.
“If the moon is very small – for example, small enough that we haven’t discovered it yet – then the tidal forces will almost certainly be strong enough to tear the moon apart.”
Even with the most powerful ground-based telescopes, many of the moons we don’t know about are too faint to see.
‘Planets and moons do not shine by themselves; they only reflect the light of the sun,” says Professor Hendry.
‘For a moon that orbits quite far from a planet that is itself very far from the sun, there isn’t much sunlight to reflect.
‘That’s why it takes such powerful telescopes to see them at all, and why they haven’t been discovered before.’
Dr. Scott S. Sheppard, an astronomer at the Carnegie Institution for Science who discovered the new moons around Uranus and Neptune, doesn’t think there are only “thousands” of moons left to be found as NASA suggests.
Enceladus – Saturn’s sixth largest moon – is a frozen sphere just 500 kilometers in diameter (about one-seventh the diameter of Earth’s moon). It is depicted in this image taken by NASA’s Cassini spacecraft
Neptune’s moon Triton (pictured) is known to be geologically active and has an atmosphere composed largely of nitrogen, just like Earth
But he agreed that we are currently unable to detect them because they are “too small and faint to see with current technology.”
“Our current largest telescopes in the world are still limited in how deeply they can image efficiently, so that’s why we have those limits for discovering the moon,” he told MailOnline.
‘All these undiscovered moons are small, measuring only a few to tens of kilometers in size, and so would not be ideal for current life
‘But they could have the ingredients for life on their surfaces, as they are thought to be ice-rich with organics on their surfaces.
“These moons are the leftover remnants of a once larger population of objects involved in the formation of the planets, so studying these moons gives us a better understanding of what happened to form the planets.”
His three new discoveries bring Neptune’s total number of known moons to 16, while Uranus now has 28, although this is still modest compared to the solar system’s two largest planets.
Jupiter has 95 moons and Saturn a whopping 146 – and this number is rising regularly.
Of course, the likelihood that life exists beyond Earth increases when you take into account planets and moons beyond our solar system – known as ‘exoplanets’ and ‘exomoons’.
NASA thinks there are billions of exoplanets alone, some of which certainly have similar conditions to Earth for life to thrive.