chapter 6 Flashcards
How do eyes and cameras work?
Your eye brings rays of light to a focus (or focal point) on your retina. Glass lenses work similarly, so distant objects form an image that is in focus on the focal plane. A camera has a detector at the focal plane, which can make a permanent record of an image.
What are the two most important properties of a telescope?
A telescope’s most important properties are its light-collecting area, which determines how much light it gathers, and its angular resolution, which determines how much detail we can see in its images.
What are the two basic designs of telescopes?
A refracting telescope forms an image by bending light through a lens. A reflecting telescope forms an image by focusing light with mirrors.
How does Earth’s atmosphere affect ground-based observations?
Earth’s atmosphere limits visible-light observations to nighttime and clear weather. Light pollution can lessen the quality of observations, and atmospheric turbulence makes stars twinkle, blurring their images. The technology of adaptive optics can overcome some of the blurring due to turbulence.
Why do we put telescopes into space?
Telescopes in space are above Earth’s atmosphere and the problems it causes for observations. Most important, telescopes in space can observe all wavelengths of light, while telescopes on the ground can observe only visible light, radio waves, and small portions of the infrared.
How do we observe invisible light?
Telescopes for other than visible light often use variations on the basic design of a reflecting telescope. Radio telescopes use large metal dishes as their primary mirrors. Infrared telescopes are sometimes cooled to very low temperature. X-ray telescopes use grazing incidence reflections rather than direct reflections.
How can multiple telescopes work together?
The technique of interferometry links multiple telescopes in a way that allows them to obtain the angular resolution of a much larger telescope.
