Galileo Galilei, an Italian astronomer and mathematician from the 16th century, was the first man to take a close look at the Moon with a telescope. As he stared through the telescope for the first time, he couldn’t believe what he saw. Huge mountains, craters, highlands and valleys made up the breathtakingly beautiful lunar landscape.
Several years after Galilei’s discovery, another Italian astronomer named Giovanni Battista Riccioli created a map on which he named the largest ‘seas’ of the Moon (see image below). In reality, these seas are dark valleys that look like seas. No liquid water exists on the lunar surface, just some ice in deep craters. Because Riccioli believed that the Moon was directly influencing the weather on Earth, he called some of the seas ‘Sea of Tranquillity’, ‘Sea of Serenity’, ‘Sea of Rain’, ‘Sea of Clouds’ and ‘Ocean of Storms’.
The many craters on the Moon were created a long time ago by meteorite impacts. They all have different sizes and some of them have bright rays around them, an indication of their relatively young age (the dark zones are older). On Earth, the impacts of meteorites disappear over time because of erosion: rain, wind and water smooth the surface by wearing away irregularities until only the most recent ones are still visible. On top of that, the Earth’s atmosphere burns most meteorites before they crash onto the surface. The Moon, however, has no atmosphere, which means that all craters stay intact. This is why the Moon is scarred with so many craters—and they keep increasing in number as time goes by!
Credit moon image: Gregory H.Revera / graphic: C. Provot (UNAWE)