As you all are probably well aware by now, I love astronomical photography. Whether its images taken as close to home as our moon and solar system, or pictures of the ultra-deep field, I am always left in awe as to how immense our universe is, and conversely, how small we really are. But seldom do those images really communicate the “largeness” of astronomy. It’s incredibly difficult to get a sense of scale from the images, and looking at the numbers doesn’t necessarily help. Saying that something is over two million light years away (like the Andromeda galaxy) may begin to give us a sense of the immensity of space, but really, we have no way to even begin to understand or conceive of those kinds of distances.
Then I see an image like this one. It’s of Saturn and two of its moons, Enceladus, the larger one, and Epimetheus, the tiny, almost invisible speck to the left.
Saturn and two moons. Click to see it at full resolution.
Phil Plait at Bad Astronomy describes this image.
This image shows, of course, the ringed planet itself, with the rings seen edge-on and their shadow cast across the planet’s southern hemisphere cloud tops. But look to the left, just below the rings; see that half-lit disk? That’sEnceladus, an icy moon of Saturn. It’s about 500 km (310 miles) across, which may start to give you an idea of how much area this picture covers. Even though it’s as big as my home state of Colorado, it’s positively dwarfed by the looming presence of Saturn behind it… and we’re not even seeing very much of the planet here! Saturn is over 120,000 km (75,000 miles) across, nine times the diameter of Earth.
Saturn is big.
He later goes on to write that the one thing he wishes people understood better about the universe is scale. I agree. It’s rare that a photograph conveys the sheer massiveness of the universe, and as he says, “we’ve barely dipped our toes in it.”
When I saw this image I instantly started humming Monty Python‘s the Galaxy Song; it tends to happen whenever I see a photo that really makes our relative size in the universe undeniable. I’ve included it here, have a listen and a laugh, and remember that your standing on a planet that’s revolving…