Space
The Moon Is Leaving Us. It's Our Fault.
The Moon is slowly drifting away from Earth, and scientists track it by bouncing lasers off mirrors the Apollo crews left behind. The Short explains that the tides the Moon raises get dragged ahead by Earth's spin, and that bulge pulls the Moon into a slightly wider orbit. Eventually it will look too small to fully block the Sun.
The numbers
- The Moon moves away by about 3.8 cm each year, roughly as fast as fingernails grow.
- A laser pulse takes about 2.5 seconds to reach the Moon and return.
- That timing uses an Earth–Moon distance of 384,400 km.
- In about 600 million years total solar eclipses will no longer happen.
Sources cited in the video: NASA/JPL · NASA Goddard · Scientific American · NASA Blue Marble · NASA Scientific Visualization Studio
