Well, I mentioned in my last post that I was going to haul the venerable telescope out of the garage, set it up and then take a look at Jupiter. And on the 29th September I managed to do that. (For anyone curious as to the 10 day gap between doing it and blogging it, I’m blaming workload and the fact that my computer decided to kill itself on the morning of the 30th!)
The first thing I have to say is that time hasn’t been kind to the three decade old optics of the telescope, and a suburban back garden surrounded by people who waste half their electric bills on porch lights is never going to be good for any form of astronomy. But I focused in on Jupiter and after a little twiddling of the focusing wheel and magnification was rewarded by a slightly astigmatic pale disc in the eyepiece. Tracking the telescope manually, by keeping the planet in the middle of the field of view I was able to just make out the faint banding of the Jovian atmosphere, which became clearer as my eyes dark-adapted.
What was fascinating was how quickly the techniques and mindset came back after a good few years not playing with the telescope in this way. I was also reminded that my gardening duties have been seriously ignored in recent months, based on the dog-roses that were trying to trip me up at every step.
And I was able to see three of the Gallilean moons – which immediately took me back to when I first saw the planet all those years ago. This is one of the great things about Jupiter as a target for first time telescope users; seeing teh Gallilean moons (which appear as tiny sharp pin-pricks positioned next to the planet) provides a direct historical connection to Gallileo (for whom they’re named) and his original use of a simple telescope to view Jupiter all those centuries ago.
I’ve been reminded that Astronomy is a hobby with a lineage; when we use a telescope we can share the wonder of viewing the heavens through the telescope that was experienced over the last 500 years by countless astronomers, professional or amateur. By looking at the stars with our naked eye we go back to the first time that some unknown worthy in Africa or the Middle East looked up to the skies one clear night and noticed that that patch of stars look awfully like a Sabre Tooth Tiger….
The skies are available for us all, but like everything else on our planet they’re geting polluted – perhaps time to support efforts against light pollution, starting with taking a catapult to that bloody floodlight that a near neighbour has as a porch light.
It’s interesting to note that the ‘unknown worthy’ in Africa & his descendants, indeed all life on earth owes a debt to Jupiter for acting as a ‘cosmic vacuum cleaner’ to deflect comets that pass through our solar system.
Without Jupiter’s gravitational influence meteoric impacts upon the earth would have been more frequent, like the comet that hit the earth some 65 million years ago which triggered the mass extinction of the dinosaurs.
Long period comets (with orbits of over 200 years) that find themselves hurtling towards our solar system would initially see the Sun and Jupiter (& Saturn) as a single gravitational source, it is only when it gets closer that the gas giants gravitational influence resolves into two forces and this is enough to cause a deflection leading to the comet being slingshot out of our solar system. As a result life on earth was allowed to evolve relatively uninterrupted by cosmic disaster. Except if you were a dinosaur…
Incidentally one of the best ‘basic’ telescopes I still use is a canon 200mm camera lens fitted with a telescope attachment eyepiece – the results are surprisingly good and I attribute this to the lens coating that reduces chromatic aberration (ie: it causes the different colour wavelengths to focus on one plane) as a result there is none of the ‘blue tinging’ associated with poorer quality lenses, and yes, if you can hold it still enough (a tripod helps) it is possible to see four of Jupiter’s moons.