Why do astronomy?

Why do astronomy? I mean, the pros do it really well with impossibly expensive equipment, and essentially, there is nothing left to discover right? Well, not so fast...

I just got back from an impromptu meeting of sky watchers. I have to say there is something wonderful about seeing Saturn. And the moon. And the constellations being described by someone who knows what they're talking about! About knowing how the stars move. About knowing how the a part of the world works. There's something about appreciating the beauty of a thing directly, without commentary or intermediary. It's something anyone can do, so it's democratic. It's the wide universe, which is awe-inspiring.

It doesn't make sense that seeing something through a 'scope should be any different than seeing a picture on a computer screen or a magazine, but there is a difference. The images are blurry, often shaky, but there's an analogue quality to it that's really appealing. You *know* the image hasn't been altered in any way, (at least not beyond the optics in the scope).

I feel I was quite lucky tonight to get to see Saturn, it's rings and the Cassini Division, 5 of it's moons, and the shadow of the planet on the rings. Someone claimed to see the "crepe belt" (which is a fuzzy interior ring) but I wasn't convinced (but then again I didn't really know what to look for anyway). I learned that at any point on the earth you can see exactly half the sky. I am at about 34 deg north latitude, and so I can see more of the northern hemisphere's stars, but I can see a big chunk of southern starts, too. I learned that the north star moves only about a degree throughout the year (or the night), and so the proportion of northern and souther sky does not vary over the year (it only varies according to latitude). I learned that the stars follow the sun, from east to west, through the night, and that they start a little later each night - and that this reflects the motion of the earth around the sun. I learned that when you are born an Aries this means that the Sun is in Aries, and so not visible in the night skies. I learned that the planets move in the plane of the ecliptic, which is different from the projection of the earth's equator on the star-field (which is 0 degrees declination). I learned that Beetljuice is Orion's shoulder, Regulus is his knee, and that Sirius is the brightest star in the sky (actually, I might have gotten mixed up on the Orion stuff). Tonight, Saturn was in "front" of Leo.

I still think it's weird that the rotation of the earth would cause the stars to move in exactly the same way as our orbit does. If you imagine the sky as an immense sphere, I suppose the earth's orbit isn't really that big, and can be neglected. What's happening can be understood, I guess, is that if you pick a time of night and you look at a particular spot far away from Polaris, and draw that as a line shooting from the earth. If you time lapse the rotation of the earth, that line will describe an arc on the celestial sphere. The next night, the same thing will happen, but the line will start a bit later. (This would be a perfect flash animation!)

I still don't really understand the motion of the planets, but I'm happy to have discovered some things about the stars. In particular, I'm glad to finally be convinced that its OK to visualize the celestial sphere as a rotating thing around polaris, and that I convinced myself that the orbit of the earth can really be neglected for celestial viewing (I'm sure you can't ignore it for planets!).

Some interesting what if questions: what if you were at a different lat (north pole, equator, south pole)? What if the earth's axial tilt was 0 deg rather than ~23 deg? What if it were 90 deg? What affect does you're altitude have on the visibility of the sky (I was thinking coverage, but I suppose you could also ask in respect to clarity)?

Some questions about the planets: why can we see the inner planets at all? Why doesn't the Sun always get in the way? Is there a constrained band in which they appear or do they appear anywhere? How can planets have phases - as outer planets should always be full and inner planets should always be new! What does gibbous mean anyway?

It's clear that astronomy is one of those hobbies, like baseball, that is a source of endless numbers, facts, and trivia. And like baseball, none of it is truly relevant to one's daily life, but it sure is fun!

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