Sea of Serenity

One 'eye' of the Man in the Moon

The Sea of Serenity is the round dark patch next to the Sea of Tranquility. Together they look like two eyes — that's why people see a 'face' on the Moon! At its edge, in 1972, the last astronauts landed — Apollo 17. They lived on the Moon for 3 days and brought back 110 kg of rocks.

The Sea of Serenity (Mare Serenitatis) is an impact basin 674 km across, flooded by lava ~3.8 billion years ago. Along its edges run 'wrinkle' ridges (dorsa) and the crater Bessel. At its eastern rim lies the Taurus–Littrow valley, where Apollo 17 landed (December 1972): geologist Harrison Schmitt found orange volcanic glass there. The Soviet Luna 21 (Lunokhod 2, 1973) also landed at this sea's edge and drove 39 km. Beneath the floor is a mass concentration (mascon) that tugs on orbiting spacecraft.

Fun facts

• Apollo 17 was the last crewed Moon landing — more than 50 years ago.
• Lunokhod 2 drove 39 km — a record that stood until 2014, when the Mars rover Opportunity beat it.
• The Moon's 'wrinkles' formed as lava cooled and shrank — like cracks on a cooling cake.