Mare Tranquillitatis

American  

[mahr-ey trang-kwil-i-tah-tis] / ˈmɑr eɪ træŋˌkwɪl ɪˈtɑ tɪs /

noun

Astronomy.

1. Also called Sea of Tranquility.  a dark plain in the first quadrant of the face of the moon: about 110,000 square miles (285,000 square kilometers).

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Example Sentences

Lorenzo Bruzzone and Leonardo Carrer at the University of Trento in Italy found the cave by using radar to penetrate the opening of a pit on a rocky plain called the Mare Tranquillitatis.

From BBC • Jul. 15, 2024

When Neil Armstrong said: “Houston, Tranquillity Base here. The Eagle has landed,” on the 1969 Apollo 11 moon mission, “Tranquillity” was a reference to the Mare Tranquillitatis, or Sea of Tranquillity, which Riccioli had named.

From New York Times • Mar. 22, 2023

"Mare Tranquillitatis, O dark and tranquil sea, Until he drops from heaven, Rest him there with thee ..."

From Death of a Spaceman by Schroeder, Ernest

They were at that moment ten degrees north of the equator, almost directly over the ridge lying between the Mare Serenitatis and the Mare Tranquillitatis.

From All Around the Moon by Roth, Edward

Then towards the equator, with a latitude of 5° north and a longitude of 25° west, appears Mare Tranquillitatis, the Sea of Tranquillity, occupying about 180 thousand square miles.

From All Around the Moon by Roth, Edward