The sun reigns over a vast empire of worlds, all moving like clockwork.

Everything within its realm obeys the laws of celestial mechanics defined by Sir Isaac Newton in the 17th century.

These laws allow us to predict exactly where each world will be for centuries to come.

And wherever you happen to be, if there's a moon between you and the sun, there will be an eclipse.

Of course, Jupiter, plenty of moons, and this is a rare picture taken by the Hubble space telescope in spring 2004 where you can see the shadows of three moons on the surface, three eclipses simultaneously.

Now, this kind of event only happens once every few decades.

Saturn, plenty of moons. I think these are my favourite of all the pictures of eclipses in the solar system because these are pictures taken from the surface of Mars by the Opportunity rover looking up at the sun.

And you can see Mars's moon, Phobos, as it makes its way across the disk of the sun.

So this is a solar eclipse, partial solar eclipse, from the surface of another world.

The astronomers of the future will discover that these partial eclipses can never measure up to the ones back home.