Telescopes Chapter 1 Section 2
Telescopes • What color are Saturn’s Rings? • What does the surface of the moon look like? You could use a device called a telescope. Telescope- is an instrument that gathers electromagnetic radiation from objects in space and concentrates it for better observation
Optical Telescopes • Most common of telescopes. • The optical telescope collects visible light and focuses it to a focal point for closer observation • A Focal Point is- the point where rays of light that pass through a lens meet or that reflect from a mirror and meet.
Refracting Telescopes • Refracting Telescopes- uses a set of lenses to gather and focus light • Two Disadvantages • Images are not always focused because the lenses focus different colors of light at slight different distances, so images appear slightly blurred. • The size of a refracting telescope is also limited by the size of their objective lens.
Reflecting Telescope • Reflecting Telescope- uses a curved mirror to gather and focus light from distant objects. • Advantages • Mirrors can be larger; therefore, the larger the mirror the more light being gathered • Flaws in the glass does not affect light because curved mirrors are polished. • Allow all colors of light from an object to be seen in focus at the same time
Optical Telescopes-gather visible light -loss of brightness -lens expensive -larger the lens, more magnification, but more bubbles Better Hubble Space Telescope
Optical Telescopes and the AtmosphereWhy mountains can help. • Light gathered by telescopes on Earth are affected by the atmosphere • Light pollution can make the sky look bright • Astronomers often place telescopes in dry areas to avoid moisture in the air.
Optical Telescopes in Space • To avoid interference scientist have put telescopes in space.
Importance of Light • Allows us to look back in time • Travels at 984,000,000 ft/sec. • A Light Year is: • The distance light travels in one year • Nearest Galaxy is Andromeda • 2 million light years away (fastest rocket-30,000 mi/hr)
Summary • The bending of light called Refraction. • Passing white light through a prism separates or refracts the light into different colors. • Reflection occurs when light or any other wave bounces off an object. • Reflection enables you to see objects that don't produce their own light. • Mirrors
Nonoptical Telescope-gathers invisible light http://www.youtube.com/watch?v=FSEA5_br7J0