Saturday, November 21, 2009

helped Chris

New member Chris emailed me with some astronomy questions. We had met recently at the DDO and chatted about batteries and dew combating.

Today he asked about Albireo, Jupiter, its moons, shadows and transits, and a "fifth" moon of Jupiter.

I relayed information about double stars, referring to Haas's excellent book and wikipedia. In particular, he wanted to know if Albireo was a binary system. I pointed out that we didn't know for sure but it probably wasn't, since we're not seeing changes in Position Angle and Separation. I also pointed out that star colour is an indicator of size and temperature.

I relayed information about the Galilean moons, referring to the RASC Observer's Handbook. In particular, I said that in good conditions, given the high albedo of Io and Europa, that it should be possible to see them above the surface of the gas giant.

Finally, we discussed what he saw on the evening of the 18th from Huntsville. I suggested that it was a field star he saw and not a fifth moon around Jupiter. The RASC OH says that some can see Himalia—with a real big light bucket. Still, as we both checked Stellarium, we did not see terribly bright stars nearby.

I wondered if it was possibly ι (iota) Capricornus.

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