Saturday, 12 May 2012

This ever changing world in which we're living

We are led to believe that before Galileo no one believed that the cosmos, the realms beyond planet Earth, could change and that all celestial bodies were perfect and incorruptible.  History books also tell us that everyone thought the Earth was flat until that pesky Columbus said, No, 'tis round and luckily I know a short cut to the Indies.

What Galileo did was point his telescope at things of interest up in the sky, the Moon, Jupiter, Venus and so on, and demonstrate to anyone with at least one working eye and a modicum of open mindedness, that things in the heavens weren't always quite the same as they were the day before yesterday.  And the single most corruptible of those heavenly bodies turns out to be the Sun.

One of Galileo's sunspot sketches
Before Galileo there were reports of sunspots.  But you can't just look at the Sun and see them, so those reports are very rare.  Only at sunrise and sunset do the intensely bright and damagingly hot rays of the Sun become ameliorated enough to be able to bear them for more than a split second.  Then you can see the odd blemish on the surface of the Sun with your unaided eyes.  Galileo wisely did not peer down his telescope (HEALTH AND SAFETY GONE SENSIBLE: DO NOT EVER EVER EVER LOOK AT THE SUN THROUGH A TELESCOPE, BINOCULARS OR ANYTHING ELSE WITH YOUR OWN EYES (UNLESS YOU HAVE A PROPER SOLAR FILTER OVER ALL THE LENSES AT THE OTHER END OF YOUR DEVICE) projected an image and then drew what he saw. 

SOHO-large-sunspotI used the same method myself yesterday.  I have a small, 3 inch reflector that's very handy for deep sky objects but also works nicely for projecting the late afternoon Sun onto the ceiling of my porch.  I did it to show my granddaughter something she won't see too often - a naked eye sunspot.  This one is called AR1476 and it is very big indeed, and active and could interfere with communications and electricity grids down here on the good Earth.  The NASA image left shows how large, in comparison to the size of the Sun, this sunspot is.  It was clearly visible on my porch ceiling and the grandaughter left having seen it going "Sun, mummy, spot."

 My limited technology does not extend, sadly for the moment, to solar filters and the like so I was deprived of having an even closer view.  As might have been guessed, sunspots have structure so large magnification reveals the spot to be a roiling mass of fingers of superhot gas, trained by the rippling magnetic fields of the Sun's inner structure poking through into the visible sphere.  So this photo from David Maidment in Oman (via captures even more wonderment and delight than the NASA picture:

If you have a small telescope or a pair of binoculars, take the occasional safe look at the Sun.  It is not just a yellow circle up there to warm and tan you.  It is a fascinating object in its own right. 

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