Wednesday, June 19, 2013

Galileo, Scheiner, Sunspots & Saturn

I decided to work on my Galilean-Scheiner sunspot study by conducting a test of instruments with those old optical layouts. For this, I used my facsimile Galilean and my small Keplerian.

Someone replied not too long ago that looking through a long tube Galilean telescope was akin to looking through a straw. Nothing could be more frustratingly true, but from a projection standpoint, it works much better.

However, the question must be asked, which telescope did Galileo use? The long tube instruments are incapable of projecting a full Sun; they simply have too much magnification. 

Surely, he used a smaller instrument. It was obvious, though, that it could be done, and the result is simply a mirror image.
Christoph Scheiner, however, preferred the Keplerian telescope. The Keplerian design uses plano-convex lenses for both objective and eyepiece. Like the Galilean, it is a simple two element design, but it produces a much better field of view. The tradeoff is that the image is inverted, but for astronomical purposes, this really isn't a problem. Scheiner was an early proponent of this design, and perhaps to be credited for its greater acceptance.

As expected, the images produced by the Keplerian were brighter and much clearer.

In this case, the image needs to be rotated 180°. I've enhanced it somewhat to bring out some of the sunspots.

The final test will be the creation of a Galilean eyepiece for the small Keplerian telescope, and a projection made to see if that approximates the studies performed by Galileo. In the meantime, it is clear that Scheiner does deserve more recognition for his pioneering work.

Wave At Saturn Night!

Tonight is "Wave At Saturn Night". This showed up on my Facebook page yesterday. This is the first time I've seen or heard of it. Nor am I able to find it again. But it seems like such a fun idea. Silly, yes, but fun.
Holidays like this, though, will forever be moving ones; planets fail to appreciate our calendar and seldom tarry long in one place.
Tonight, Saturn is pretty close to zenith at sunset. with a waxing gibbous Moon to its east. The white moonlight should proved strong contrast to Saturn's yellowish hue. 
If you get the chance to, be sure to take a step outside and look for Saturn, that bright yellow star north and west of the Moon.

Addendum - It was Philip Astore, amateur astronomer and professional firefighter, who made the comment about looking through a straw. Anybody who loves astronomy is a friend in my book, but this fellow also has one of the toughest jobs in the world. Stay awesome, Philip.

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