While I’ve been interested in astronomy for over forty years, it’s only in the past year and a bit that I’ve returned to that interest in any sort of “serious” way as an amateur. I’ve been poking around at various telescope shops, getting to know some other amateurs in my area, and taking a lot of nightscape photos. I’ve even started taking a few photos of the moon and Jupiter with the equipment I have. Now what?
The sky is a big place. A simple calculation gives you an idea of just HOW big it is – and I’m not talking about how deep it is in time/distance. Consider first the moon. The moon is pretty big. It has a surface area about the same size as the continent of Africa, although we only can see about half of it from Earth of course. With the existing small telescopes I have I can make out features perhaps 5 km across if the lighting is right. The surface of the moon is about 38,000,000 km^2 (km^2 means “kilometer-squared or square kilometers) so if I can see half of it (in total) that’s about 19,000,000 km^2. A crater 5 km across has a surface area of about 19.6 km^s – so that little crater is just about 1/100,000 of the visible face of the moon. The whole visible surface is a lot of territory (or lunatory) to consider. Of course, it might be better to consider the visible disk of the moon, not the near hemisphere for a comparison like this. A disk with the radius of the moon would have a surface area of about 9,500,000 km^2, so the ratio would be about 50,000 craters-worth of area to explore. Still a lot! A purist would try this with angles but the answer would be the same as the disk area sketch.
The thing is, the moon is actually SMALL compared to the visible celestial sphere. Our eyes are drawn to the moon at night, but the reality is that it’s only about a half a degree across. The whole celestial sphere, encompassing 360°, has an area of approximately 41,253 °^2 (according to a Wikipedia entry on the angular area of the celestial sphere). The moon’s disk as an angle is about 0.2 °^2 – so it would take 206,000 moons to fill up the visible area of the sky! (The sun as virtually the same angular diameter as the moon – that’s why we can have such stunning total solar eclipses – so the same thing holds. The sun, so dominant in our sky, covers only about 1/200,000 of the visible celestial sphere. From the surface of the earth only about half of the celestial sphere is visible as the sky, and the sun is about 1/100,000 of it).
The moon photographed from Hamilton, Ontario, on 2012 12 19 2125 EDT with an 80mm refractor and Nikon D5100 at prime focus. Relatively simple equipment can take nice photos – but if you are interested in going further, what’s the next step?
The sky, then, has room for 200,000 moon-faces, and my little telescopes can show me details 1/100,000 of the moon’s surface. It’s overwhelming – and full of rich detail. From massive galaxies to wispy nebulas and sparkling star clusters, space beyond our little solar system is one of the richest treasures in nature. How luck we are that we can actually see it! If our solar system was within a more complex part of space we might not have as good a view as we do. Then again, it’s a fair bet that the more “interesting” places in space are far more risky too. Our fair wee planet has had less than five billion years of life so far, and only a few major boo-boos (like the asteroid impact that killed the dinosaurs – Ooops!).
So, back to the point of this ramble. As a (re)budding amateur astronomer, where do I start? I’m faced with this question because I’m looking seriously at upgrading some of my equipment, and different telescopes do different things. Do I make use of my existing optics and improve my ability to point and shoot, with a better mount and camera? Do I invest in a better optical tube (the actual “telescope” part)?
To some degree a telescope is a telescope. There are some basic characteristics everyone needs to consider when they are thinking about this kind of thing. One of the most important is portability. Like a lot of people, I live in a small apartment; I don’t have a garage or basement for storing large pieces of kit, and I don’t have my own space for a shed or observatory. So, compact and rugged is good. I’m also watching my budget (gulp). And, of paramount importance to me, I want to embark on something of a path in learning astronomy, not just grabbing at big telescopes because they’re cool! (and they are cool, and I’m a telescope geek).
I’m thinking I’ll start in the neighborhood this year, seeing what I can see – and photographing what I can photograph close to home in the “planetary” range – the sun, moon, and planets. This narrows things a bit, and is also a good choice for an urban dweller. Despite light pollution in cities, our own solar system is still quite observable from our sidewalks and parks because the objects are so bright. The existing ‘scopes I have – an old 80 mm refractor and a 130 mm “starter” Newtonian reflector – will do for now. What I need to do is to consider in the short term is what’s under the telescope and what’s attached to it.
Telescope mounts are important and perhaps underappreciated parts of the whole “system.” A heavy, capable mount makes viewing anything much easier. A lightweight mount only has the advantage of light weight. Small mounts shake. If you adjust a small telescope on a light mount it can take five or ten seconds or more for the resulting vibration in the camera to dampen out. So, I’ll be paying attention to mounts.
Cameras are at the other end of the process. There are some things I can do with my dSLR cameras, but the best images today are actually being taken with cameras that are much simpler than a dSLR but are designed to be used with a telescope – and a computer. Derived essentially from webcams, most cameras that work brilliantly for planetary photography by amateurs have small-seeming sensors – often less than a megapixel. They are also specialized in two other ways. They often have a built-in cooler, to help control internal camera noise – and they are often monochrome. Yes, black and white. You can do a lot in black and white, and you can get colour images by taking a series of monochrome images through coloured filters. The image files (often actually captured as short video segments in AVI format) are then processed with some ingenious computer software to create stunning, sharp images. So, I’ll also be looking at a small, specialized camera designed for planetary imaging. By starting with a camera and a sturdier mount, I can get going and will consider upgrading the optics a little later.
I’m also sure that there will be lots of opportunities to peek out past our solar system in the coming year. I’m going to be making visits to observatories, star parties, and other events to soak in more of deep space – and of course to be able to make reports here at Pine River Observatory! And I’ll be spending time under the night sky doing wide-field photography and just wandering around the stallar back-yard with binoculars and a good star guide. There are many lifetimes of space out there to enjoy.
© 2012, David Allan Galbraith
Pine River Observ-atory 