Review of the William Optics 102 GT
May 25 2015 11:22 AM by Perseus_m45
Review- Printing Astro photos on Metal with Bay...
Apr 16 2015 02:36 PM by ScenicCityPhoto
16” F/4.5 Teeter Stark Review
Apr 15 2015 02:46 PM by donsell
Vixen Ascot Super Wide 10x50 Binocular Review
Apr 15 2015 11:02 AM by jvandyke
Categories See All →
- CN Reports
- User Reviews
- How to . . .
- Observing Skills
- Astronomical History
- Optical Theory
- Vision and Related Experiments
- How to Gain the Support of your Family for your Astronomical Pursuits
- Evaluation Tips
- Special Events
- The Elements
- New Articles in [!monthname!]
- Telescope Articles
- Submit a Review / Article
- Monthly Guides
- Behind the Scenes
- About Us
- Copyright ©
- Terms & Conditions
- Tiny Eyes on the Skies
- From the Editor's Desk
- What's Up . . .
- The Light Cup Journals
- Who is this Super Light Cup?
- Cloudy Nights T-Shirts
- Imaging Contest
- Small Wonders
- Previous Imaging Contest Winners
- This Month's Skies
- Mike's Corner
- The Cloudy Nights Friends and Family Discount
- Uncle Rod's Astro Blog
- Fishing for Photons
- Binocular Universe
- Article Submissions
When the sun is on the horizon, then the line between darkness and light created by the glowing sun and the shadow-casting earth is sweeping through your position. It's called the terminator as it terminates or ends the daylight. The terminator passes overhead twice a day with sunrise and sunset. At sunrise, the effects of the daily pageant play with darkness giving way to light, while for sunset the sequence is simply reversed. Descriptions here with the sunset will mean things that can happen at both times of day.
Amateur astronomers and telescope makers have debated from time immemorial the advantages and disadvantages of different telescope designs. In particular, mountains of hard copy and electronic articles are available on the merits of refracting and reflecting telescopes, more recently, apochromatic refractors vs. Newtonian reflectors. This debate has become rather rancorous (Newtonian telescopes as APO "killers" comes to mind.) and unscientific, to say the least. And when all is said and done, in a discourse without loaded words and acrimony, a discussion devolves to one concerning perfect optics. And isn't this what we all want or wish we had?
Sunsets, sunrises and twilight, as well as clear blue skies and the less familiar crepuscular rays, mirages and green flashes are all examples of atmospheric optical effects that can be readily seen at many times of the year from many places on the earth. No special equipment beyond your eyes, a bit of patience and an openness to learn is needed to see and feel the beauty of the interaction of natural light and the air.
Most craters on the Moon are named after famous individuals associated with our satellite, and those on Mare Crisium, the 'Sea of Crises' are no exception. After a little map reading, I decided to make the focus of my evening’s viewing a pair of craters named after the founders of two of the most famous Observatories on Earth.
This glossary was complied largely from a thread called “Astronomy Terms for Fun” on the General Observing Forum of Cloudy Nights.
I have devised a laser collimation test for Cassegranian systems. An on axis laser beam falling onto a 3M type reflective film creates a “virtual pinhole.” The backscattered light is sufficient to form an adjacent image from the primary that may be adjusted until it is brought into coincidence with the “virtual pinhole. This collimates the primary and allows the secondary to be collimated by conventional process, similar to Newtonians.
A process is described, utilizing readily available resources, for the fabrication of super-lightweight graphite-epoxy thin-wall tube structures. The heart of the process is in the compression molding tooling, which yields smooth exterior surfaces, and in the breakaway mandrel that forms the inside wall.
I had a set of Synta mirrors in storage which I had taken out of my Orion XT-6. I wanted to build a scope for them and after giving the project some thought I decided to build a strut Dob out of wood. The intended purpose of this scope would be for use at lower magnifications on deep sky objects. With a lot of miscellaneous stuff lying around, as well as access to a lot of scrap materials and discarded items, one of my goals became to build the scope as economically as possible while reclaiming and recycling as much as I could. The project would also be a good learning experience and an opportunity to try out different design ideas. The entire Dob was made with only a few old power tools and hand tools, as well as a small drill press and a Harbor Freight mini-lathe. I used a portable work bench I made to do all the wood cutting and sanding in my back yard. The rest of the work was done in my single car garage.
Not into “heavy scientific” work? Just want to enjoy the colorful rainbows of other stars, or see the fascinating absorption line detail in the solar spectrum? A number of options, some quite inexpensive, are available to display spectra for you.