Binocular observation of Jupiter and the moon
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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!
