Jupiter at opposition, sketched with cold fingers
Jupiter was at opposition yesterday, on the 10th. That means the Earth sits directly between it and the Sun: Jupiter rises at sunset, is up all night, and is as close and as bright as it gets this year, at magnitude −2.7 or so. This year it is in Gemini, below Castor and Pollux, which puts it very high in the sky by midnight. High matters more than close for a small telescope. Less air to look through.
Last night was clear from about nine. The Moon, near last quarter, did not rise until after midnight.
| Time | Notes |
|---|---|
| 21:15 | Telescope out to cool. Air −1 °C. Dew shield and hand warmer on. |
| 21:50 | First look at 28×. A bright disc and its moons in a ragged line, unevenly spaced. Naked eye, Jupiter outshines everything in that part of the sky by a wide margin. |
| 22:00 | 70×. Seeing poor to start, the disc boils. Two dark belts, though, without any effort. |
| 22:30 | Seeing settling. Belts have texture now: the northern one looks lumpy along its edge. |
| 22:40–23:20 | Sketching. See below. |
| 23:25 | Fingers gone. Inside. |
The sketch
I drew a circle in advance, slightly flattened, because Jupiter is visibly wider than it is tall and I always forget. Then the belts, as two soft bands, rubbed in with a fingertip. Then forty minutes of looking and adding things only when I was sure.
The northern belt ended up darker and wider on the drawing than the southern one. The polar regions came out greyer than the equator, which I did not notice until I had to decide what to do with the top and bottom of the circle. And on the southern edge of the southern belt there was, for a few moments at a time, a small notch or paler bay that I marked with a question mark. It may have been the Great Red Spot, or the hollow it sits in. I am not confident, and at 70 mm I did not expect to be. The page says "?" and that is the honest record.
Over the forty minutes the moons shifted. Not much, but enough that the one closest to the disc on my first note had visibly changed its distance by the end. That is the part of Jupiter I never get tired of: a system you can watch move in an evening, with a pencil.
The sketch is not good. The belts are too straight and the disc is smudged where my glove touched it. It is still a better record of the night than anything I could have done with the phone.