Stars & Galaxies 6.1 & 6.4

Reflecting Telescope

Uses mirrors to collect and magnify light

Refracting Telescope

uses lenses to magnify light

Light enters through the lens first, refracting the light to the eyepiece, which collimates the image for the observer

Area of gathering light equation

A = pi(d)²/4

CCD (charged-coupled device)

Takes images of the light observed

Space-based telescopes

to observe x-rays from high energy sources (like black holes or jupiter’s auroras)

Optical telescopes

On the ground

for stars/asteroids

Infrared telescope

In space

to observe planet properties

Turbulent Air

blurs images

Adaptive Optics

Technique to remove atmospheric blur

3 basic components of a telescope

the telescope…

a sorting instrument for wavelengths

a detector

Detector

a device that senses the radiation in the wavelengths regions we have chosen and permanently records the observations

Observatories

a special site for observing the sky

Telescope

serves as a “bucket” for collecting visible light

Important functions of a telescope

collecting and focusing light

Aperture

the telescopes diameter of a mirror or reflecting surface

Lens

transparent piece of material that bends the rays of light passing through it

Focus

An image of the light source appears

Focal Length

The distance from the lens to the location where the light rays focus (image) behind the lens

Eyepiece

Used to view the image

different eyepieces change the magnification (size) of the image

Chromatic Aberration

Image is distorted because optical properties of transparent materials change a little with the wavelength of light

image appears blurry

Components of measuring radiation from space

telescope, detector, and filter

What type of focus are most large, professional telescopes?

cassegrain focus

Cassegrain Focus

Light is reflected by the secondary mirror down through a hole in a primary mirror to an observation station below the telescope