Scale

It’s odd, it’s only in the last few months that I realised just how small the Moon is in relation to the Earth. Sure, I knew it was smaller, but I hadn’t thought about that fact in any detail probably in decades. If you asked me how much smaller I’d probably have guestimated somewhere about somewhere less than an half and greater than a third the size diameter (see comments) of the Earth. But no, the Moon is considerably smaller than that again.

How much? Well, look at these images here, about or a little less than a quarter the diameter.

And that’s interesting because recently looking at the Shadow of the Moon documentary, and this is probably what unconsciously sparked my thoughts in this direction, it seemed to me that the journey from the Command Module to the surface of the Moon seemed quite short. Very short. And it probably was, even accounting for editing, because the Moon has a surface area about that of Asia. Indeed look again at the image above and you’ll see that set up against the Earth (let’s not try that experiment for real – eh, folks?) it would be about as ‘high’, as Africa.

But that sparks a further thought. How far away is it? Well, the easy answer is that it’s … of course it is. But let’s think about that in more human terms of scale. Here’s the ever excellent Phil Plait’s Bad Astronomy blog and a post on just this matter.
If the Earth is the size of a basket ball and the Moon a tennis ball, and the ratio is more or less spot on, more rather than less I hasten to add, then the Moon would be 24 feet away! That’s quite a distance. There’s a bunch of videos on YouTube that show what other planets would look like if they were orbiting the Earth at the same distance as the Moon. I can’t say how accurate they are, some are probably there or thereabouts.

But as Plait says:

I’m sometimes asked what’s the one thing I wish people would understand better about the Universe. My answer is always the same: scale. We humans have a miserable sense of just how big space is, and I’ve spent a lot of time over the years working out ways to express it better.

And:

Space is big. Very, very big.

And using the same scale Plait makes a very thought provoking point. How far away is the nearest star from Earth?

It would be — to scale, mind you — 800,000 km (480,000 miles) away: twice as far as the real Moon is from the real Earth!

I’ve been thinking a lot about the prospects for human interstellar travel, and I’m moving to a position where I wonder if sheer scale is just too great a challenge, at least for the foreseeable future. Humans are notoriously bad at future planning, and there’s no proof that our artefacts can survive the sort of time spans required. Add those together and the lack of viable technologies and the future looks… isolated.

Charles Stross deals with this issue here… and funnily enough Robert Silverberg in the current edition of Asimov’s raises the point in a slightly different context.