And, because the Moon is tidally locked with Earth, meaning we always see the same side, you can track how the terminator changes night after night. You can also explore the lunar surface online, either by using Google Moon , by visiting the Lunar Reconnaissance Orbiter website or by downloading the excellent JMars software used by actual NASA planetary scientists! Located close to the edge of the lunar limb is Mare Anguis, which roughly shaped like an X.
It lies near the rim of the much larger Mare Crisium, elevated m above. To its east is the 7km wide Eimmart A crater.
Located on the very edge of the Moon, Mare Australe is only visible when libration tips the Moon forward enough to see it. Unlike most of the other smooth maria, Australe is pockmarked by impact craters which then flooded with basaltic lava. The Surveyor 3 soft lander would follow in , paving the way for the Apollo 12 crew to arrive in The main basin of Mare Fecunditatis formed in the pre-Nectarian era — the earliest time period just after the Moon formed.
However, material surrounding it dates from later eras. The crater overlaps with surrounding Nectaris, Tranquillitatis and Crisium basins. The northernmost sea, along the top of the Imbrium and Serenitatis basins, Mare Frigoris has an intriguing elongated shape, averaging only m wide but stretching to over 1,km in length.
Located to the east of Frigoris, Mare Humboldtianum is right on the northeastern limb of the Moon. Due to the slight wobble of the Moon from Earth an effect known as libration , the sea is sometimes hidden from view. The name is a reference to this location, bridging the gap between the known and the unknown, and so it was named after Alexander von Humboldt, a Prussian natural scientist born in who was famous for travelling the world and exploring places no European had visited before.
The basin is surrounded by a ring of mountains, rising up as much as 7km above the mare floor, and there are signs of ejecta radiating out as far as km from the crater. Located on the far side of the Moon, Mare Ingenii makes up part of the South Pol-Aitken basin — a huge lunar feature that covers most of the southern hemisphere.
The region contains the km wide Thomson crater. Insularum is hemmed in by the prominent Copernicus crater to the east, the Kepler crater to the west and joins up with the large Oceanus Procellarium in the southwest. The northern edge is bordered by the Montes Carpatus while the south merges into Mare Cognitum. Unlike Europa, no ice geyser activity has yet been spotted. This could be because of a reduced tidal effect on the moon, which is further from Jupiter than Europa.
Unlike Europa, it doesn't have the cross-hatched icy surface showing consistent geologic surface activity. Still, the signs are good that Ganymede is harboring an ocean.
Callisto is similar in composition to Ganymede and, as the furthest out of the four Galilean moon of Jupiter, is bombarded with the least amount radiation. It also has a magnetic field, adding some additional protection.
We know there's water here—what we don't know is to what extent it's liquid. Callisto's relative lack of geologic activity suggests that the moon might not be able to sustain an ocean without the presence of some kind of anti-freeze compound within, meaning that there could be just a whole lot of ice in there.
However, as the farthest out of the satellites, it could make an interesting destination for exploration, allowing you to avoid the harsher effects of Jupiter's radiation while remotely exploring the other moons for signs of oceans and life. The Red Planet probably once had oceans, including one covering a good chunk of the northern hemisphere.
There are traces of water left on the surface, including compounds from the evaporation of the ancient ocean, as well as seasonal water ices covering the surface of the planet. There is some evidence pointing to occasional melting on the surface as well. That much is clear. But there's an intriguing possibility that Mars still has water underneath the surface, possibly in the forms of aquifers. Theoretically, these underground waterways could still host microbial life under the surface of Mars.
The question, then, is whether this water exists as ice or liquid, and how much of it lurks beneath the soil. An entire ocean's worth is unlikely, but a significant amount of subsurface water isn't. Future missions, like the Mars rover and Russia's ExoMars probe, will look specifically for signs of organics and water under the martian surface.
The team behind NASA's Cassini probe, which has turned up many of the exciting findings about Saturn and its moon, joking called Dione a "weaker copycat of Enceladus. It's possible that the moon retains enough of that heat for a small ocean to exists. New Horizons will fly by Pluto this summer , becoming the first spacecraft to directly visit the world once known as the ninth planet. It may discover something that once seemed unlikely: an ocean. Pluto is still seen mostly as an icy world.
However, the tidal forces from its orbit with its largest moon Charon—combined with what scientists the violent formation of the system a large collision likely formed Pluto and its five moons out of the same materials —means Pluto could have hosted a ocean, and leaves open the outside possibility that it's still around.
It seems odd not to be able to include Titan, Saturn's largest and arguably most fascinating satellite, on this list. Titan has some of the most abundant pools of liquid found anywhere in the solar system, but those come in the form of methane, a hydrocarbon chain that's good for life, but not necessarily as we know it. Still, Titan deserves to be mentioned in any tally of potentially habitable places because of its resemblance to early Earth. So here it is.
Mimas, the "Death Star moon ," is pretty much one big snowball. There doesn't seem to be much more to it than water ice. Yet a few unusual features hint at something weird on Mimas. The moon wobbles as it orbits Saturn, which indicates something unusual going on beneath the surface. The Cassini team says that it could be an ocean. But only maybe. The other chief possibility is that Mimas has a football-shaped core giving it the unusual tilt.
At around the size of Enceladus, the moon is too small to retain the heat from its formation, so any ocean on Mimas would have to have an outside force acting on it—possibly radioactive decay. Neptune's largest moon, Triton, looks a lot like Pluto.
There's a reason for that. Section 1: The lunar seas. See also. Image gallery: Lunar seas Pete Lawrence's Moon guides. Other sections. Section 2: Bright and dark craters You will need to use binoculars for this section. Section 3: Craters in Shadow You will need to use binoculars for this section. Section 4: Majestic mountains You will need to use a telescope for this section.
Section 5: Lunar specials You will need to use a telescope for this section. By format: Documentaries.
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