One of my favourite Iain Banks ideas: If aliens exist, you'll find them watching a solar eclipse on Earth.

"What an incredible coincidence it is that our moon fits exactly over our sun. Talk to astronomers and they’ll tell you that Earth’s moon is relatively much bigger than any other moon round any other planet. Most planets, like Jupiter and Saturn and so on, have moons that are tiny in comparison to themselves. Earth’s moon is enormous, and very close to us. If it was smaller or further away you’d only ever get partial eclipses; bigger or closer and it hide the sun completely and there’d be no halo of light round the moon at totality. This is an astounding coincidence, an incredible piece of luck. And for all we know, eclipses like this are unique. This could be a phenomenon that happens on Earth and nowhere else.

"So, hold that thought, okay?

"Now, supposing there are aliens. Not E.T. aliens – not that cute or alone. Not Independence Day aliens – not that crazily aggressive – but, well, regular aliens. Yeah? Regular aliens. It’s perfectly possible, when you think of it. We’re here, after all, and Earth is just one small planet circling one regular-size sun in one galaxy. There are a quarter of a billion suns in this one galaxy and quarter of a billion galaxies in the universe; maybe more. We already know of hundreds of other planets around other suns, and we’ve only just started looking for them. Scientists tell us that almost every star might have planets. How many of those might harbour life? The Earth is ancient, but the universe is even more ancient. Who knows how many civilisations were around before Earth came into existence, or existed while we were growing up, or exist now?

"So, if there are civilised aliens, you’d guess they can travel between stars. You’d guess their power sources and technology would be as far beyond ours as supersonic jets, nuclear submarines and space shuttles are beyond some tribe in the Amazon still making dugout canoes. And if they’re curious enough to do the science and invent the technology, they’ll be curious enough to use it to go exploring. “Now, most jet travel on Earth is for tourism. Not business; tourism. Would our smart, curious aliens really be that different from us? I don’t think so. Most of them would be tourists. Like us, they’d go on cruise ships. And would they want to actually come to a place like Earth, set foot – or tentacle, or whatever – here? Rather than visit via some sort of virtual reality set-up? Well, some would settle for second-best, yes. Maybe the majority of people would.

"But the high rollers, the super-wealthy, the elite, they’d want the real thing. They’d want the bragging rights, they’d want to be able to say they’d really been to whatever exotic destinations would be on a Galactic Grand Tour. And who knows what splendours they’d want to fit in; their equivalent of the Grand Canyon, or Venice, Italy, or the Great Wall of China or Yosemite or the Pyramids?

"But what I want to propose to you is that, as well as all those other wonders, they would definitely want to see that one precious thing that we have and probably nobody else does. They’d want to see our eclipse. They’d want to look through the Earth’s atmosphere with their own eyes and see the moon fit over the sun, watch the light fade down to almost nothing, listen to the animals nearby fall silent and feel with their own skins the sudden chill in the air that comes with totality. Even if they can’t survive in our atmosphere, even if they need a spacesuit to keep them alive, they’d still want to get as close as they possibly could to seeing it in the raw, in as close to natural conditions as it’s possible to arrange. They’d want to be here, amongst us, when the shadow passes. “So that’s where you look for aliens. In the course of an eclipse totality track. When everybody else is looking awestruck at the sky, you need to be looking round for anybody who looks weird or overdressed, or who isn’t coming out of their RV or their moored yacht with the heavily smoked glass."

(from the novel "Transition")