Big skies

An amazing thing happened to me tonight while I was out running.

We have an incredibly boring night sky. Don't get me wrong: It's one of the most breathtakingly beautiful things we have to look at. But there are only two objects in the entire sky larger than point sources.

But there are places that have vertiginous views of the heavens. From the Moon, the Earth is a good-sized coin in the sky; the Sun viewed from Mercury is about the same size. And Jupiter's moon Metis is at a third of the distance that our Moon is, while Jupiter is 11 times larger than Earth. That means that if you were a miner in the far distant future walking around on the surface of Metis with your pickaxe and your spacesuit, Jupiter would appear 132 times larger than the Moon; it would take up 66 degrees of the sky, or a third of the distance from horizon to horizon. Can you imagine the vertigo induced by having something that large career overhead?!

(Asimov does a great job of articulating these kinds of celestial details in some of his earlier works--perhaps the Lucky Starr series?)

Back to running tonight. As I rounded a corner, there was one of those rare confluences of coincidence. There was a roughly-circular cloud formation which was being shaped into a series of approximately a dozen parallel bands by the wind. They were whispy cirri that were not immediately obvious in the dark. As I rounded the corner, the pattern-recogniztion subroutines of my brain were triggered by my peripheral vision and identified what they thought was a huge sphere floating in the sky. It literally made me jump as a Jupiter-type body appeared to be filling 20% of the sky. Even when I looked directly at it, the illusion persisted; it was perfect cloud paraeidolia. It was also a truly remarkable vision of what living in a system blessed with such scenery would be like--the standard sci-fi huge-planet-in-the-sky doesn't really compare to actually seeing what appears to be an indescribably massive object seemingly suspended in the real-world sky.

This brings up a related point: This is probably the third or fourth such occasion where I've seen a celestial event that could have been confused with a UFO by a less scientifically-minded individual. All of those "It was just Venus" explanations offered by scientists always sound pretty lame as explanations of UFO phenomena--until it actually happens to you. Last night I literally saw a cloud out of the corner of my eye that made me jump. And I remember another occasion driving due east to work at dawn. In that case it really was Venus in the sky that freaked out my peripheral vision due to miss-applied motion. Its extreme brightness (and the solidity of buildings) fooled my sensors into thinking it was moving and the buildings were standing still rather than that it was stationary and the buildings were gliding past.