The Face the Moon Hides
When the first pictures of the Moon's hidden side came back in 1959, scientists were puzzled. It looked like a different world.
What was reported
The Moon always shows the same face to Earth, so for all of human history, half of it was hidden. In October 1959, the Soviet probe Luna 3 flew behind the Moon and sent back the first blurry photos of the far side.
They showed a surprise. The side facing Earth is covered with large, dark plains, the 'seas' that make the face of the man in the Moon. The far side has hardly any: it's almost all bright, rough, heavily cratered highlands. Later missions showed its crust is also much thicker.
Explanations offered
Scientists still debate why the two sides are so different. One idea is that soon after the Moon formed, the young Earth was so hot that it heated the near side, so that its crust stayed thinner and lava later flooded through it. Others point to a giant impact or the way the Moon cooled. The far side is sometimes wrongly called the 'dark side', but it gets as much sunlight as the near side.
- When
- First photographed in October 1959
- Where
- The far side of the Moon
- Witnesses
- The Soviet probe Luna 3, then many spacecraft
- Status
- Partly explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.