Friday, 27 October 2017

The Stars Around Sirius

The 26th of October the sky was dull and overcast and it rained in Cambridge. However, after midnight the clouds cleared and the night sky was clear and moonless. I had hoped to photograph the Pleiades with the Tudor telescope but it was impossible to locate them as they were high in the sky towards the west.  It took seconds to locate them with the unaided eye but after 5 minutes of fruitless searching with the Tudor telescope I gave up. (I took one photograh that they might be on but its 50:50 certainty at best.) A major disadvantage of the Tudor telescope is the small field of view. Its hard to navigate the night sky and to be sure exactly what is being imaged and facing backwards makes it doubly hard. The Moon is easy to find and so is Venus because both objects are so bright. The easiest way to get a star in line with the telescope mirror is to to chose one that is near to the horizon that is vertically above a street light or chimney or tree branch then to point the telescope towards the object on the horizon and move it upwards.  This is how I imaged the Andromeda Galaxy a few night ago by moving the telescope upwards vertically from a fence post in my back garden. This morning the star that was easiest to find was Sirius, the Dog Star. It was due South and just above a chimney on  roof at the end of my road. A red arrow marks the spot.

I located the house roof, found the chimney, moved the telescope up and within a few minutes I had Sirius in sight. I took about 10 photographs of the sky around Sirius with my Canon Ixus 160 and the best one is reproduced below.

Sirius is the bright star over on the left  and Beta Canis Majoris (also called Mirzam - the herald)  is the next brighter star to the right. In addition another 10 fainter stars can be seen that were invisible to my unaided eye.  Although we will never know if Thomas Digges or Thomas Harriot ever pointed their perspective glasses towards the stars if they had have done so they would have seen that the night sky contained more stars than were known at the time and that the stars did seem to occupy an infinite space. Biron in Love's Labour's Lost (Act 1 Scene 1) comments on the futility of naming every star in the night sky.  When seen through the Tudor Telescope there are just too many stars to count and catalogue.

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