Astro 102 Observing Report, 2/18

Lining up to see the moon.

Monday lab finally got their turn at the observatory last night. Some high clouds were a a problem, especially around 8:00 but nothing bad enough to keep us from our appointed tasks. Our sessions consisted of a visual sky tour and celestial sphere orientation. Then we looked at the crescent moon and Jupiter through one of the 8″ scopes. Seeing was good. Cloud belts and all four Galilean moons were visible. We then looked at the Great Orion Nebula, a starforming cloud over 1,000 light years away. We had telescopic views of Rigel (B8) and Betelgeuse (M2) to see a contrasting pair of spectral types. We concluded each of the two sessions with a brief tour of the observatory building.

The high clouds did cause a moon halo for a while, seen below. It’s caused by hexagonal ice crystals and always appears 22 degrees from the moon. Orion (lower left), Jupiter (right of the moon), and the Pleiades (farther right) are all visible. Note that the moon, which was just past first quarter, is overexposed to allow the  fainter halo to be photographed.