Mississauga Astronomical Society
Thirtyseventh Meeting
Speaker’s’ Night
Day: Friday, April 1, 2005
Guest Speakers: David O’Neill
Ron Brecher
Speaker: John Boyd
Sketching at the Eyepiece
David and Ron met 2 years ago at a failed meeting of an astronomy club and then during a sketching session at the eyepiece. They now regularily observe and sketch astronomical objects.
Sketching objects allows the observer to look rather than just see. More detail can be noted at the eyepiece due to extended viewing of the object. Critical questions can be asked such as “is it round or elliptical?”, “bright or faint star”, etc. A sketch is a record of what to look for, is a part of an observing log and is creative and artistic. It captures the moment: “What am I seeing right now?”
David showed examples of his early and late sketches, showing the evolution of his skill. He had sketches of many Messier objects including galaxies, open clusters showing smudging technique for unresolved stars (M25, M23), open clusters with nebulosity (M8), globular clusters, planetary nebulae.
Ron also showed examples of his early and late sketches, Jupiter, Comet Ikeya-Zhang, the sun and Venus transit, and deep sky objects.
Practical considerations include warm clothing, a safe site, chair, sketching platform, table, dark adaptation except for solar system objects, red light directed to the drawing and templates for planets, and circle for eyepiece view. Soft pencils HB, 2B, 4B, 8 (progressively from light to dark), technical erasers and putty for texturing for dark nebulae are also used. Ron stressed that the eyepiece circles be drawn large enough, e.g the size of a coffee mug. One should draw what one sees, not what one expects. Star dots can be tidied up the next day. Different magnifications can be used for the sketch.
Various techniques are used for different objects and by different observers. David uses light materials and fills in detail whereas Ron uses dark marks and erases later. With nebulae, galaxies and globulars, Don starts at the centre and builds shape outwards, lightly edging boundaries of features. Ron starts out of focus to record the faintest stars and gradually focuses in to draw ever fainter stars; finally he adds in the object of interest.
In summary, sketching costs little, gets better with practice, and trains the observer to see more detail.
Tycho Brache
Last September, John and Dairne Boyd visited the island of Hven in Denmark where Tycho Brache had his observatory. John described the life of Tycho and showed pictures of their trip to Hven.
Born as Tyge in 1546 at Knutsdorp Castle in Denmark and raised by an aunt and uncle he changed his name from Tyge to the more Roman sounding Tycho. Being of noble birth meant that he was ale to devote his life to study. He had private tutors and at age 12 entered the university at Copenhagen where he studied law and rhetoric. The Aug. 21, 1560 lunar eclipse encouraged him to study astronomy. In 1566, an argument over who was a better mathematician led to a duel in which part of his nose was hacked off. After that, Tycho wore a silver/gold nosepiece. In 1568 he took over the canonry of Roskilde where he worked in astronomy, glassworks, alchemy.
Tycho noted that Jupiter and Saturn did not always appear in the sky where predictions would put them. This encouraged him to make more accurate observations. In 1572 a new star appeared in Cassiopeia, which we now know as a type 1A supernova. As a result of this dramatic event, King Frederick II understood that his future depended on surrounding himself with intellectuals. He first offered Tycho a castle. Tycho refused this but then accepted when the king granted him an island and its wealth for an astronomical observatory.
In the 15th century astronomy believed that all stars were at the same distance far away because no parallax or interstellar motion was visible. Earth was felt to be in the centre of the universe. Some planets showed retrograde motion. To explain this motion and better characterize these observations, Tycho built Uraniborg in the centre of the island of Hven. This included the observatory, home, lab, garden, printing press. At its peak, Uraniborg used up 5 % of the GNP of Denmark. To get even more accuracy, Tycho then built adjacent Stjerneborg. Astronomical instruments included a large azimuth quadrant and a great equatorial armillary. The larger the instrument, the more accurate star positions could be measured. Tycho observed every clear night and employed 30 graduate students. In addition, all residents of the island had to work 1 day per week for Tycho.
In 1596, a new king Christian IV ascended the throne. Tycho, with his arrogance and rudeness lost favour with the new king and departed to Prague. Neighbours destroyed the property on the island. Tycho died in 1601 after a party. Hair analysis later showed mercury poisoning.
Tycho’s legacy involves the meticulous and accurate naked-eye measurement of planet and star positions over decades, a team approach to observing, and the laying of foundations for Keppler. Measurement errors were only ½ to 1 arcsec. Tycho looked for evidence of heliocentricity but could not find it.
John showed slides of the island, the reconstructed Stjernborg and the location of Uraniborg which is now only a field. The buildings have been destroyed but formal gardens restored.
Submitted by Chris Malicki, Secretary Chris Malicki, Secretary
back to M.A.S. meeting reports page
Mississauga Astronomical Society