Binocular observation of Jupiter and the moon

When I was young, I used to be quite into astronomy (I was into a lot of things before computing came along and hypnotised me to the exclusion of much else for a big chunk of my life which I'll never get back). I never owned a telescope or even, as far as I recall, binoculars, and to be honest I'm not sure I even felt the need. I grew up somewhere moderately remote, where light pollution wasn't really an issue, so you could just go outside and look up on a clear night and behold the Milky Way whenever you felt like it. Shooting stars and satellites were things you could easily spot multiple times on any given night. I had one of those little rotating cardboard wheel star chart things, and I learned my way around the sky pretty well and spotted plenty of planets. I guess maybe all of this is more what you would call "stargazing" rather than amateur astronomy per se, although maybe that's a bogus and snobbish distinction to draw. I guess it took a while even after the internet and computing appeared in my life for this interest to completely wane, I remember taking a degree of geeky pride in making the objectively unwise decision to interrupt my sleep at some ungodly hour the night before my final high school physics exam in order to watch a meteor shower (I still did fine). And I was even in my university's astronomy club, although to be honest that was mostly just a social club for hypernerds and any kind of genuine astronomy-based event was outnumbered more than ten to one by quiz nights, video nights, fundraising BBQs, etc. Good times, to be sure, but I spent more time staring at the skies by myself as a kid. Until very recently, it had been definitely over a decade since I'd done *anything* like any of the above.

I recently decided, almost on a whim, but definitely conceptualising it as a continuation and expansion of my ongoing...oh, I don't even know what to call this thing that I'm going through anymore. My ongoing pivot away from computing? I'd rather define it more in terms of what it *is* than *isn't*, but haven't got that totally worked out yet. Anyway, I decided to buy a pair of binoculars, for the express purpose of astronomical observation. I actually considered an entry-level telescope as well, but in the end I was swayed by the facts that it seemed like you could get modest but certainly decent astrobinos at a price point where any available telescope was still not much more than a toy, that binoculars are much more easily transportable without a car (important because sadly I no longer live somewhere where light pollution is not a problem), and that binoculars are somewhat less single-purpose devices, and can be just as easily used for birds and other wildlife. I got a pair of 10x50 binoculars (10 times magnification, 50mm apertures), these being widely regarded as the best to use for astronomy without requiring a tripod for stability (prior to researching this purchase I didn't even know tripod-mounting binoculars was a thing, but it definitely is), specifically the Opticron Adventurer T WP 10x50 model, chosen mostly after reading "if there is a better 10x50 for under £125, I’ve not seen it" at binocularsky.com, a very approachable site which I took a liking to during my research, especially because all the content there is under a CC license. I bought them back in the middle of summer, which didn't actually make an awful lot of sense astronomy-wise, as it wasn't getting even vaguely dark until way too late at night, and in fact according to the sunset time app that I already had installed on my phone for radio purposes, "astronomical sunset" (did you know there are at least four different definitions of sunset?) was literally not even happening. Even now I suppose it is relatively early in the season and so I have not really started using the binoculars for their intended purpose in earnest yet. But I've done enough that I felt like I wanted to write a little about it.

In fact, when I bought these, I really had one thing in mind as a concrete goal that I'd be really excited to achieve. To my surprise, I got the opportunity to cross this off my list much earlier and much easier than I ever expected, and it was also more impressive than I ever expected. This was to observe the four largest moons of Jupiter, the so-called Galilean moons: Io, Europa, Ganymede, and Callisto. I was surprised to read that this was even possible with "just" 10x binoculars, and I had prepared myself for something relatively uninspiring. Kind of like I can tell you observing Saturn is - ten times magnification is not enough to really see the rings distinctly as rings, although you can tell that they are there because Saturn looks "slightly squished", rather than perfectly round. But actually these views aren't comparable at all, which retrospectively makes sense. Take a look at a picture of Saturn, you can see that inclusive of rings it's roughly twice as wide as it is high. But the orbital radii of the Galilean moons are substantially larger than the radius of Jupiter itself, meaning the whole scene can become a lot more widely spread out in your field of view than Saturn and its rings, which are confined to a small blob. I had the good luck of making my first observation on a night and at a time when all four of the moons were a decent distance away from the planet itself, and indeed it was fairly easy to see each individual moon as a separate point of light. Looking again the next night, it was also clear to see that their positions had shifted, precisely the same kind of observation which led Galileo to conclude over 400 years ago that they were, in fact, orbiting Jupiter. It's a real treat to be able to so easily and with such humble equipment replicate a scientific observation of this kind of historical significance! Okay, it was easier than it otherwise might have been as I once again had the good luck of, without any prior planning, doing this at a time when as it turns out Jupiter was simultaneously closer to the Earth than on average and on the opposite side from the sun, making for optimal viewing conditions. But I don't think this kind of observation is prohibitively difficult under more typical conditions, otherwise it wouldn't have first happened over 400 years ago. This is definitely something you can do too if it interests you enough.

While waiting for darker skies to become a thing in the summer, I used the binoculars primarily for observing the moon. Like a n00b, I paid special attention to full moons because, hey, that's when you can see the most stuff, right? And, to be honest, I had a perfectly enjoyable time doing exactly that, comparing what I saw against maps and picking out all the easily visible high-albedo craters, learning the names of the various maria (they sure don't *all* appear in Schismatrix!), looking up the landing spots of the Apollo missions. But actually it transpires that full moons are widely considered sub-optimal lunar observation times, because the intense and direct light casts no shadows, making the whole thing look very flat. When the moon is less than full, you can really clearly see shadows around the edges of craters, especially near the terminator, and the landscape looks astonishingly three dimensional. It's really quite incredible how even in this day and age where we have all seen photos and videos from the surface of the moon, it still requires (at least for me) a genuine conscious effort to conceptualise it an honest-to-goodness *place*, with a three dimensional shape, and geographic features, and *smaller places on it*, which have their own names - as opposed to it just being this bright disc that you can see in the sky sometimes. A few binocular observation sessions is a good antidote to this, at least for a while.

Sunset is already coming sooner and sooner. I guess I will need to start looking into some traditional binocular astronomy targets, nebulae and the like, which I might have a chance to spot in the winter despite less-than-perfect-dark here. Recommendations welcome!