Book contents
- Frontmatter
- Contents
- How do you get to Albireo?
- How to use this book
- Using your telescope
- Know your telescope
- The Moon
- The Planets
- Seasonal skies: January–March
- Seasonal skies: April–June
- Seasonal skies: July–September
- Seasonal skies: October–December
- Northern skies
- Southern skies
- Where do you go from here?
- Behind the eyepiece
- Acknowledgments
- Tables
- Index
- What, where, and when to observe
- Finding geostationary satellites
Know your telescope
Published online by Cambridge University Press: 05 January 2013
- Frontmatter
- Contents
- How do you get to Albireo?
- How to use this book
- Using your telescope
- Know your telescope
- The Moon
- The Planets
- Seasonal skies: January–March
- Seasonal skies: April–June
- Seasonal skies: July–September
- Seasonal skies: October–December
- Northern skies
- Southern skies
- Where do you go from here?
- Behind the eyepiece
- Acknowledgments
- Tables
- Index
- What, where, and when to observe
- Finding geostationary satellites
Summary
Galileo discovered the four major moons of Jupiter (forever after called the Galilean satellites in his honor); he was the first to see the phases of Venus and the rings of Saturn; he saw nebulae and clusters through a telescope for the first time. In fact, a careful checking of his observations indicates that he even observed, and recorded, the position of Neptune almost 200 years before anyone realized it was a planet. He did all this with a 1” aperture telescope.
Charles Messier, who found the hundred deep-sky objects in the catalog that bears his name, started out with a 7” reflector with metal mirrors so poor that, according to one account, it was not much better than a modern 3” telescope. His later instruments were, in fact, 3” refractors.
The point is this: there are no bad telescopes. No matter how inexpensive or unimpressive your instrument is, it is almost certainly better than what Galileo had to work with. It should be treated well. Don't belittle it; don't apologize for it; don't think it doesn't deserve a decent amount of care.
Get to know your optics
An astronomical telescope has two very different jobs. It must make dim objects look brighter; and it must make small objects look bigger. A telescope accomplishes these jobs in two stages. Every telescope starts with a big lens or mirror called the objective. This lens or mirror is designed to catch as much light as possible, the same way a bucket set out in the rain catches rainwater.
- Type
- Chapter
- Information
- Turn Left at OrionHundreds of Night Sky Objects to See in a Home Telescope – and How to Find Them, pp. 18 - 23Publisher: Cambridge University PressPrint publication year: 2011