May 2022

AP Corner June 2022; Finding Your Focus Part 2

By Don Sellesw.jpg

In Part 1 of this article, I described several techniques you could use to manually focus your smartphone or your DSLR used either stand alone or attached to your telescope. Adding an inexpensive Bhatinov mask to the front of your telescope or DSLR lens (yes you can get them that size) makes achieving critical focus using the camera’s live view focusing very doable. This technique can also be used for a dedicated astro-imaging camera on your telescope if you view the focus images as they are downloaded to the computer controlling the camera.

The Bhatinov mask works great, but let’s face it, manual focusing can be a tedious and time-consuming task. When I first started astro-imaging, manual focusing was the norm for me and others like me starting out because the motorized focusers were few, and they were rather expensive. In addition, there was not much software to automate the focusing process and there were no real interface standards to allow computer control of the telescope focuser. So, we learned to focus by hand and by eye. 

Messier Column June 2022

by Jim King


I find myself compelled to once again, give credit where credit is due.  While Charles Messier basks in the glow of his famous catalogue of non-comets, he had help!  During his collaboration with Messier, Pierre Mechain added 25 or 26 objects to Messier’s catalogue (depending on how one looks at M102).

These include Messier’s 63,72,74,75,76,77,78,79,85,94,95,96,97,98,99,100,101, 102(?), 103, 104, 105,106,107,108,109… a sizable addition to Messier’s work.

Pierre Méchain was born in Laon, the son of the ceiling designer and plasterer Pierre François Mechain and Marie–Marguerite Roze. He displayed mental gifts in mathematics and physics but had to give up his studies for lack of money. However, his talents in astronomy were known to Jerome Lelande, for whom he became a friend and proof-reader of the second edition of his book "L'Astronomie". Lalande then secured a position for him as assistant hydrographer with the Naval Depot of Maps and Charts in Versailles, where he worked through the 1770s engaged in Hydrographic work and coastline surveying. It was during this time—approximately 1774—that he met Charles Messier, and apparently, they became friends. In the same year, he also produced his first astronomical work, a paper on an occultation of Aldebaran by the Moon and presented it as a memoir to the Academy of Sciences.

In 1777, he married Barbe-Thérèse Marjou whom he knew from his work in Versailles. They had two sons: Jérôme, born 1780, and Augustin, born 1784, and one daughter. He was admitted to the French Académie des Sciences in 1782, and was the editor of Connaissance des Temps from 1785 to 1792; this was the journal which, among other things, first published the Messier Objects. In 1789 he was elected a Fellow of the Royal Society.

Why the Moon Has Two Faces

By William Sager


Every astronomer knows that the Moon has one side facing the Earth, the near side, and another side, that cannot be seen, the far side. This occurs because the Moon’s rotation exactly matches its orbital period. Until the Space Age, nobody had seen the far side. Starting with the Soviet Union’s Luna 3 in 1959, spacecraft began sending back pictures of the far side and today we have high-resolution images thanks to NASA’s Lunar Reconnaissance Orbiter (LRO). Even a casual glance reveals that the near and far sides appear vastly different (Figure 1). The near side contrasts high-albedo anorthosite highlands with dark basaltic lowland plains named mare by early observers who thought they were seas. (Note: anorthosite is an igneous rock consisting mainly of potassium felspar whereas basalt is an igneous rock rich in iron and magnesium). In contrast, the far side is mostly anorthosite with only a few small, scattered and isolated mare. In a recently published paper in the journal Science Advances, a multi-university team led by Matt Jones of Brown University reported having worked out the reason for the Moon’s two faces.

Why the Stars Shine

By: Don Selle

First published in the October 2012 issue of the Guidestar


“It is reasonable to hope that in the not too distant future we shall be competent to understand so simple a thing as a star.”  Arthur Eddington

“Science is the one human activity that is truly progressive. “ Edwin Powell Hubble

“I can find in my undergraduate classes, bright students who do not know that the stars rise and set at night, or even that the Sun is a star.”   Carl Sagan

Humans are creatures of habit, it’s built into us.  It’s an evolutionary adaptation that enhances our chances of survival in the natural world. We like things to be normal and routine, and for most of us, it takes a lot to change our patterns of behavior and of thought. 

But nothing progresses if it is constant or follows the same patterns over and over again. Because our thought processes follow common, established patterns, we often need a challenge to jolt us into finding a “new normal”, a new way of looking at things. 

Solstice Shadows, Night Sky Network June 2022

by David Prosper


Solstices mark the changing of seasons, occur twice a year, and feature the year’s shortest and longest daylight hours - depending on your hemisphere. These extremes in the length of day and night make solstice days more noticeable to many observers than the subtle equality of day and night experienced during equinoxes. Solstices were some of our earliest astronomical observations, celebrated throughout history via many summer and winter celebrations.


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