Last Friday saw two events that had astronomers on the streets, out in the frozen winter nights, wherever there was a clear sky. First there was the Moon, intensely bright. Due to the orbits of the Moon around the Earth and the Earth around the Sun being ellipses rather than simple circles, the distances between the Moon and the Earth and the Earth-Moon system and the Sun change. With a change of distance comes a change of brightness for the Moon, which reflects sunlight back toward the Earth. The most recent full Moon was the brightest of 2010. The comedian Eddie Izzard tweeted from LA that he could see a ring around the Moon, starting off a series of tweets that included pictures of different lunar effects and discussions of the ice particles that lead to the optical effect of the ring being formed.
However, attention also focused on a little red dot to the left of the Moon (as seen from Kendal). This was the planet Mars and it was at opposition. As the Earth and Mars spin around the Sun on their elliptical orbits, the Earth undertakes the red planet. As this happens, Mars looms closer and so appears brighter in the sky (and larger). The point at which the Earth lies between Mars and the Sun is called opposition.
As with the changing size and brightness of the Moon due to the vagaries of orbital mechanics, Mars reaches a different size and brightness at each opposition as the Earth catches it at different parts of its orbit. Opposition this year left the planet large enough for details to be seen in a moderate sized telescope (over six inches). Of course, not everyone has such an instrument to hand, so the Eddington Society, the Astronomical Society of Kendal, put on a public observing session at Abbot Hall park.
When I first arrived, the thing that struck me was the number and variety of telescopes. There was a small refractor, the society Dobsonian, a second, very long Dobsonian, Stuart Atkinson‘s Newtonian and a couple of others besides. I added my own Celestron 130SLT to the pool. There were also a few cameras doing the rounds, to which I also added my own efforts, and a few pairs of binoculars, with the owners happily learning to scan the sky with them. The public observing events are growing in size and popularity, although the cold weather did keep general public numbers down compared to warmer previous observing events. The crowd would also have been thinned by there being fewer queues for the greater number of available telescopes.
I set up the 130SLT using solar system align, which is a rough and ready alignment for the telescope motor tracking system that is nevertheless good enough for events like this. I simply input the location, time and align Mars (or whatever) in the centre of a good magnification eyepiece and the telescope keeps the thing in place, even at higher magnifications. Another 130SLT user came over to chat about alignment methods. I mentioned the three star, two star and solar system alignment ways (in decreasing order of robustness).
The initial views of Mars through the SLT were of a jittery red dot that slowly settled into a calmer disc. I could kid myself and say there was a little detail at my highest power eyepiece, but as Percy Lovell should know only too well, faint lines have been inferred to be on Mars before more as a result of wishful thinking than actual observation.
Of course the views of the Moon and Mars occured at a rather auspicious time as Obama made clear his intention to cancel the manned space program that was to use the Moon to step onto Mars. At the same time, the Mars Rover Spirit looks as if it will rove no more. Still capable and intending to do science for the forseeable future, the Spirit rover has become trapped in a submerged crater filled with some rover grabbing dust. The team announced last week that their present efforts haven’t succeeded in freeing the stricken craft and they’re now considering science proposals for what they can do with a stationary but operational rover. First thing’s first though, Martian winter is heading Spirit’s way and so the solar panels are being readied for rover hibernation. Meanwhile, other hardware on Mars continues to operate as planned including both the Opportunity rover and the HiRISE satellite. Do you want to help choose a bit of Mars for the satellite to point its high definition camera at? Then we have an app for that…
Other popular targets on the night included the nearby Moon, which was sporting Eddington Crater, of obvious interest to the society. Another was the Beehive cluster, M44, an open star cluster visible to the naked eye under very dark skies, which sat inbetween the Moon and Mars. Despite the solid brightness of the Moon, the cluster still showed a good grouping of brighter stars, 500-600 light years from us. Finally, there was the Orion nebula. When seen through the longer Dobsonian, this was rendered in high contrast in a good widefield eyepiece.
The event started about sevenish, I arrived about half past and we all reluctantly wrapped up at nine, before making our frozen way back.