We recently saw the excitement of a total solar eclipse over Exmouth, Western Australia.
A total eclipse is when the sun, moon, and Earth are in a perfect line - called a syzygy. As the moon goes around the Earth every 29 days, the moon changes its position relative to the Earth and the sun.
As the moon goes through this movement, the way the moon looks, when it is lit by the sun or in darkness, changes and so does our view of it. This is known as the phases of the moon.
When we get a new moon, the side that is facing away from us, the far side, is completely illuminated by the sun and the side facing us is dark. It also means the moon is between Earth and the sun, and sometimes the sun is blocked by the moon as viewed by Earth - giving us a solar eclipse.
But what would the view be if you were on the moon during this?
Well if you were facing the Earth, you'd see the moon's shadow go across the Earth - it would look more similar to a lunar eclipse on Earth.
At other times, as the moon keeps going around the Earth, the side we see is now in sunlight, or a full moon. It also means the Earth is now in between the sun and moon. Occasionally the alignment is perfect and the moon is in the shadow of the Earth, giving us a lunar eclipse.
However, if you were on the moon during his alignment, you would be getting a solar eclipse - the Earth, not the moon would be blocking the sun. This is exactly what astronauts of Apollo 12 saw.
A special release of Apollo 12 footage of a total eclipse from the 70mm camera archive can be viewed here.
On average, the moon is 384,400 kilometres away from the Earth. The sun, however, is much further, about 149,600,000 kilometres, or nearly 400 times further. The sun though, is much bigger than the moon - 1,392,000 kilometres in diameter compared to 3474 kilometres, or about 400 times bigger.
This means that when this perfect alignment happens, the moon can entirely block the apparent size of the sun in our sky - a total solar eclipse.
However, as the Earth is much bigger than moon, during a solar eclipse from the moon, the Earth appears to be much bigger than the sun and blocks it completely.
The sun is so bright though that it causes the Earth's atmosphere to glow.
Eclipses have also been seen on some of the other planets. Mars has two moons - Phobos and Deimos. Both are very small, only tens of kilometres wide, so when they cause an eclipse, they do not cover the entire size of the sun.
However, many of the rovers on Mars, including Perseverance, have spotted these Martian solar eclipses.
Planets like Jupiter and Saturn, have even more moons, 95 and 83 respectively. Some of the moons of Jupiter are larger than our moon.
This means that with all these moons, the number of eclipses is large, with each moon able to cause its own.
Whether on Earth, the moon, or even another planet, spotting an eclipse is always a treat.
- Brad Tucker is an Astrophysics and Cosmologist at Mt Stromlo Observatory and the National Centre for the Public Awareness of Science at the ANU.
