A successful observing night was held on Friday 18th November at North Turramurra. We had four members with scopes in attendance and two visitors who had found us through our web site. The scopes were 16, 12, 6, and 4 inches.
Before it got dark, we spotted Venus and Mercury a couple of degrees apart, low in the west. However they were too low to see in our scopes.
We then turned our attention to Jupiter which was already quite high. Only three moons were visible, but we could clearly see a black spot on the planet’s surface. A check with my Sky Safari software revealed that Io was in transit and we were seeing its shadow on the planet’s surface. In fact the shadow was right next to the Great Red Spot! Jupiter is just past opposition and is also close to perihelion (its closest approach to the Sun) meaning that the planet appears at almost its largest possible angular size (currently 49 arcseconds). This, and an unusually stable atmosphere, made for a magnificent view of the planet even at very high power.
At about 9.40pm, we watched as Io emerged from the transit and appeared as a pimple on Jupiter’s limb. Here is a picture I took through the eyepiece showing Io emerging with Ganymede nearby.
Jupiter with Io on the limb and Ganymede nearby
Some of the other objects we observed during the night…
47 Tucanae – globular
M31 – The Andromeda Galaxy
NGC6752 – globular in Pavo
NGC7009 – The Saturn Nebula (a tiny blue elongated object)
M42 – The Orion Nebula (magnificent through an Ultra High Contrast Filter)
M79 – globula in Lepus (very small and faint)
M41 – open cluster in Canis Major
M77 – spiral galaxy in Cetus
The evening also produced some dew which caused us some problems. Since our last dew-filled observing session (on August 26th) I had installed dew heaters on my scope and this was the first time I was able to try them in dewey conditions. The result was good. All the optical surfaces were cleared of dew soon after switching on the power and remained clear the whole night.
At about 10.15pm some thin cloud began appearing overhead. We then had intermittent periods of cloud for the remainder of the evening. We were able to view a few more objects in the clear patches, but by 11pm the sky was almost fully covered with thin cloud so we packed up for the night.