Haunted Observatory - Richard Baum

This is not a Scooby Doo-esque mystery about a guy in a rubber mask trying to scare everyone out of an observatory. It's a more a series of stories about astronomers prior to the 20th Century thinking they've spied something that it turns out they didn't actually see. Or something that they may have seen, but no one else could ever find again.

Sometimes it's a star, or possibly a comet. Something that glows brightly for a day but then dims swiftly and ultimately vanishes. On one occasion, the guy is certain he's found the planet that is throwing off Uranus' orbit. In fact, he'd screwed up so badly he was actually just looking at Uranus. Or the belief, held for quite some time, that Venus had mountains near its poles that rose above the clouds that envelop the world. There's an entire chapter on the notion the Moon might have its own satellites, and the search for those (undertaken for a time in the 1950s by Pluto discoverer Clyde Tombaugh.)

The chapters range from 10 to 50 pages depending on the topic. Some chapters I reached the end and still didn't know what had happened. Why did they think they saw mountains above Venus' clouds catching sunlight? In some ways, Baum writes for novices, as he'll spend a paragraph or two giving a short biography for one astronomer or mathematician or another that is relevant to the chapter. 

In other ways, the writing feels very technical. Much discussion of ascensions, of trying to observe this planet or that in superior opposition at such-and-such right declination. Some of it may be relevant - at least one of the mysteries is ultimately due to the astronomer not realizing he twisted the wrong dial when adjusting his telescope and thus getting his values crossed - but at others it just feels like too much detail. I think he's trying to split the difference between the human urge to stare the sky and dream, and the fact that searching the night sky - really, truly searching it - can be a methodical, tedious process. One where the slightest error, or even just an imperfection on the mirror if you're using a reflecting telescope, can throw you off completely.

'On March 10 and 12, 1790, Schroeter had taken great care to distinguish the bright hook peculiar to the southern cusp from the twilight arc. The twilight arc, as we have just seen, he ascribed to scattered light in the upper atmosphere. The hook at the southern cusp, however, he attributed to a ridge of high mountains that catches the direct light of the sun.'