Background
Although Galileo didn’t invent the telescope, he was the first to turn his telescope to the sky. It doesn’t take a powerful telescope to revisit Galileo’s discoveries: the largest moons of Jupiter, the craters on the Moon, the presence of millions of stars not visible to the naked eye, the rings of Saturn, and the changing phases of Venus. What if you had a telescope of your own that you could use to verify Galileo’s discoveries and more?
Learning Goals
- Research the various kinds of “high-end” telescopes available.
- Clearly explain the basis for the purchase.
- Summarize the specifications of the telescope, giving values for the aperture, focal length, focal ratio, and magnification.
Part 1: The search
Let’s imagine you were given $2500 to purchase a telescope. (Why so much? Cheap telescopes are a waste of money. They rarely give satisfactory results and thus are quickly abandoned.) There are many on-line retailers that would be pleased to help you out. Find a telescope that you would buy with that amount of money, excluding taxes, shipping, and handling.
Sky & Telescope has a great summary of “Simple Formulas for the Telescope Owner” at https://skyandtelescope.org/observing/stargazers-corner/simple-formulas-for-the-telescope-owner/. The article defines terms and gives examples of the math to use to answer the questions if the information isn’t provided .
After reading the Sky & Telescope information and finding the perfect telescope for you, summarize your purchase by answering the following questions in a well written essay (don’t just answer each question separately).
1. Would you choose a refracting telescope or a reflecting telescope?
2. Why did you choose that kind rather than the other?
3. What features does it have? Why are those important to you?
4. How large of an aperture does it have? (convert inches to millimeters, if necessary)
5. What is the focal length of the objective lens or primary mirror? (usually given in mm)
6. What is its f-ratio (focal ratio)?
7. Are multiple eyepieces included? What magnification would each eyepiece give you during your observations using your new telescope?
(Beware of cheap telescopes that claim to give magnifications of 100 or 200 times or more. At those magnifications, it is extremely hard to get a sharp focus and accurately tracking deep sky objects is nearly impossible.)
8. Would you use part of the money on accessories? If so, which ones and why?
Part 2: The summary
Be sure to provide full details on your final “purchase,” including the retail merchant you chose. Bring in information from any lessons on telescopes that is relevant to your decision. As usual, good writing style and accurate use of punctuation and language are required.