What are lunar seas?

Lunar seas (maria) are the dark and relatively smooth plains on the Moon.

They were once thought to be bodies of water but we now know that they are actually vast, ancient lava plains.

The lava fields are the result of volcanic eruptions that occurred during the Moon's early history, between about 4 and 3 billion years ago.

Lunar maria cover about 20 percent of the lunar surface and are concentrated on the Moon's near side, which is the side that is always facing towards Earth.

The majority of the lunar maria are located on the northern hemisphere of the Moon, with the Mare Imbrium being the largest and most prominent lunar sea.

Lunar seas are considered to be some of the most geologically interesting and important features on the Moon, and they have been the subject of extensive scientific research and exploration.