The most interesting moons of our solar system
There are only eight planets in our solar system (sorry Pluto), so the neighborhood can feel pretty empty. But there is more than 200 moons orbiting objects in the solar system, including planets and large asteroids.
Many of these moons have atmospheres, complex topography, and even weather systems. They are dynamic, volcanic and exquisite objects for space agencies trying to learn more about the diversity of planetary bodies and their satellites.
Some moons are bigger than planets and some are little more than space rocks – but all can offer clues to how our modern worlds came into being. Here are some of the most intriguing moons (large and small) orbiting our solar system.
Surely you have heard of this one. Big, pockmarked, definitely not hollow? Earth’s moon is sometimes known by its Latin name, Luna, but its proper English and astronomical designation is simply Moon.
It’s been visited many times – in fact, there’s a rover on it right now – but it’s sure to get much more interesting with the upcoming Artemis missions, which will see human astronauts return to our only satellite.
The Artemis missions are likely to tell us a lot about the geological history of the Moon, given the advances in technology since the last lunar samples were collected. It is also planned to build a Lunar Gateway Space Station on the satellite, paving the way for future space exploration. Thanks, Moon!
Phobos and Deimos
Phobos and Deimos are two Martian moons, measuring 27 km and 14 km in diameter respectively. So far, space agencies did not succeed land spacecraft on either moon. But as is the case with our Moon, Phobos and Deimos likely have details of Mars’ formation locked away in their rock strata. Phobos’ orbit also shrinks as it circles Mars, which means the moon can either crashing into Mars or being torn apart by the planet within the next 100 million years. We should have expected this from the planet named after a god of war.
The tiny Cocksfoot was only discovered by chance; in 1993, NASA’s Galileo spacecraft rocked by an asteroid named 243 Idaand spotted a small moon orbiting the space rock.
Dactyl proved that asteroids could have moons, and thanks to Galileo we have an image of the tiny satellite, likely born from the same collision of ancient objects that created Ida.
The smallest of Jupiter’s moons, Europa is a tempting target for planetary scientists and astrobiologists. Europa is covered in ice, under which there is a world ocean of water. Because life as we know it only exists in the presence of water, Europa is a prime candidate to investigate extraterrestrial life.
However, other elements of the moon are inhospitable, namely Jupiter’s radiation, which, as Gizmodo previously reported, could obliterate any signs of life we see from afar. This makes the prospect of landing a spacecraft on Europa all the more appealing; it is easier to see life up close.
A small moon of Jupiter (small meaning it’s just slightly larger than Earth’s Moon), Io has hundreds of volcanoes dotting its surface that spew lava tens of kilometers into its sky; combined with its thin, sulphurous atmosphere, the moon is pretty hellish. Jupiter’s immense tidal forces cause the moon’s surface to shift several hundred feet. Since the moon is so hot and unstable, all sightings of Io have been done remotely.
Pan & Atlas
Pan and Atlas are two adorable little moons of Saturn, and both have a flying saucer shape reminiscent of the ringed planet they orbit. They are also tiny, with radii of less than 16 km. The moons were first imaged by the Voyager program, and were later imaged by the Cassini spacecraft (which ended its career by plunging into Saturn itself).
Other moons Saturn’s moons have similar ridges along their equator, indicating that the way Saturn’s moons formed caused the pronounced and irregular shapes of Pan & Atlas.
Charon is a moon of Pluto, and it is small compared to other moons in the solar system, but large compared to its parent body, which was once considered the smallest planet in the solar system. Together, the two bodies form the only known dual planetary system, in which the same sides of Pluto and Charon always face each other. (For comparison, an observer on Earth always sees one side of the Moon, but on the Moon you would see all sides of the Earth as it rotates).
Charon is a relatively recently discovered solar system moon, discovered by a United States Naval Observatory astronomer in 1978.
Nereid is one of Neptune’s outer moons and is notable for its interminably long orbit. It takes the distant moon about 360 Earth days (nearly an Earth year, if you count correctly) to complete one revolution of its host planet.
It is difficult to observe from Earth, but Voyager 2 observations in 1989 indicated that Nereid is an icy moon. With new telescopes coming online soon, we may soon see more of Nereid.
Titan is Saturn’s largest moon and the second largest in the solar system after Jupiter’s Ganymede. But Titan is especially interesting for its dense atmosphere and its enormous oceans of methane. NASA plans to launch a spacecraft there in about five years.
We already have an image of Titan’s surface, taken by the Huygens probe that landed on the moon in 2005. It gave us a tantalizing enough glimpse to want to come back to.