The lunar marias are dark spots on the Moon that resemble oceans, but are actually made of dark rock. They were formed by ancient volcanic eruptions caused by tidal heating and are mainly located on the near side of the Moon. The first manned mission to the Moon landed in a minor lunar mare, the Sea of Tranquility.
The lunar marias (singular: mare) are the dark spots on the Moon. Maria means “seas” in Latin, and the lunar marias get their name because of their ocean-like appearance in contrast to the lighter spots on the Moon. Despite the name, they’re not water, just a darker type of rock. The Moon is completely devoid of any liquid moisture, although scientists believe water molecules may be present in some locations. The first mission to land a man on the Moon, Apollo 11, landed in a minor lunar mare, the Sea of Tranquility, and the lunar module’s lower stage is still there today.
The lunar maria formed between 3.16 and 4.2 billion years ago, as measured by radiometric dating, although crater counting methods suggest that some portions may have formed as recently as 1.2 billion years ago. They are flood basalts formed by huge ancient volcanic eruptions on the Moon, similar to the eruptions that caused mass extinctions on Earth 251 million years ago. Lunar maria exist mainly on the near side of the Moon. The far side, which cannot be seen from Earth, and has only been photographed by a few space probes, is almost devoid of air.
The eruptions that caused the lunar maria got their heat source from tidal heating: heat caused by the slight deformation of the Moon as it makes its way around the Earth’s gravity well. Over millions of years, this heat can build up underground until it is enough to trigger a volcanic eruption. As these massive eruptions took place, the resulting lava flows seeped into the lower parts of the Moon, many of which are impact basins. The South Pole-Aitken Basin on the Moon, the largest known impact crater in the solar system, is only modestly covered in marine basalt.
Most manned missions to the Moon have landed in the lunar seas, due to their relative flatness compared to the lunar highlands. Rock samples have been returned from both lunar highlands and maria, and differ significantly in their contents. Rocks in the sea have a higher iron content, which is partly responsible for their darker color.
Protect your devices with Threat Protection by NordVPN
