390 likes | 545 Views
Telescopes. Galileo 1609. The Moon as a World. Jupiter has Moons. Refracting telescopes. Isaac Newton’s reflecting telescope. Reflecting telescope. Objective mirrors instead of lenses. Three Powers. Magnifying Resolving Light Gathering. Magnifying Power.
E N D
Reflecting telescope Objective mirrors instead of lenses
Three Powers • Magnifying • Resolving • Light Gathering
Magnifying Power • Ability to make objects appear larger in angular size • One can change the magnifying power of a telescope by changing the eyepiece used with it • Mag Power = focal length of objective divided by the focal length of the eyepiece
Resolving Power • Ability to see fine detail • Depends on the diameter of the objective lens or mirror
Light Gathering Power • The ability to make faint objects look brighter • Depends on the area of the objective lens or mirror • Thus a telescope with an objective lens 2 inches in diameter has 4 times the light gathering power of a telescope with a lens 1 inch in diameter
Refracting telescopes Lick Vienna
Yerkes Observatory
20th century Large Reflectors Come of Age Mount Wilson
4 meter Reflecting telescope
Dome of 4 meter Kitt Peak
Astronomical “seeing” • Blurring effect of looking through air • Causes stars to twinkle
Bad seeing on this side Good seeing on this side
Observing from space • No clouds • Perfect seeing • Can see wavelengths of light blocked by the earth’s atmosphere