# 7telescopes4s

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Education

Published on January 17, 2008

Author: Minerva

Source: authorstream.com

Telescopes and Spacecraft:  Telescopes and Spacecraft Astronomy 311 Professor Lee Carkner Lecture 7 If it is low tide where you are standing right now, how many total places on Earth are at low tide right now? How many total places on Earth are at high tide right now?:  If it is low tide where you are standing right now, how many total places on Earth are at low tide right now? How many total places on Earth are at high tide right now? 1 and 0 1 and 1 1 and 2 2 and 2 4 and 4 Which of the following would the Earth’s magnetic field have no effect on?:  Which of the following would the Earth’s magnetic field have no effect on? An ion An electron A neutral oxygen atom A negative hydrogen atom A positive helium atom How Do Telescopes Work?:  How Do Telescopes Work? Telescopes: Focus light to produce an image Light gathering ability (not magnification) is the most important attribute of a telescope telescopes make faint things brighter Lenses:  Lenses Need a lens Lenses bend light (refraction) and focus all of the light incident on the front to a point (focus) a certain distance behind the lens (focal length) Lenses and Refraction:  Lenses and Refraction Refracting Telescope:  Refracting Telescope This produces a refracting telescope mag.= f.l. objective / f.l. eyepiece in practice the magnification you can achieve is limited by the blurring effects of the Earth’s atmosphere Refracting Telescope:  Refracting Telescope Refractors and Reflectors:  Refractors and Reflectors Makes them A curved mirror can be used to gather and focus the light instead (reflecting telescope) large mirrors are easier to make and support Reflecting Telescopes:  Reflecting Telescopes Problem: The focal point is between the mirror and the sky Cassegrain Telescope -- secondary reflects light through a hole in the primary, most common type of large telescope Cassegrain Reflecting Telescope:  Cassegrain Reflecting Telescope Telescope Misconceptions:  Telescope Misconceptions Magnification is the most important property of a telescope image quality and light gathering ability (size) are what is important Astronomers peer through an eyepiece Telescopes stick out of the dome Telescopes fold up like a giant pirate’s spyglass The Electromagnetic Spectrum:  The Electromagnetic Spectrum Every photon (light particle) has a wavelength which places it in the electromagnetic spectrum long wavelength -- low energy short wavelength -- high energy We see different wavelengths of visible light as colors red -- blue -- We want to view all types of electromagnetic radiation So we can explore all physical processes The Electromagnetic Spectrum:  The Electromagnetic Spectrum Telescope Taxonomy:  Telescope Taxonomy Radio and Millimeter penetrates atmosphere and everything else Infrared (IR) some penetrates atmosphere, but to observe all IR wavelengths need to go into space Optical it helps to get above atmosphere (no blurring = sharper images) More Telescope Taxonomy:  More Telescope Taxonomy Ultraviolet (UV) some penetrates atmosphere, but to observe all UV wavelengths need to go into space X-ray all X-rays blocked by atmosphere Gamma Ray all Gamma rays blocked by atmosphere Least Energy Orbit:  Least Energy Orbit Once in space they coast to the planets, following Kepler’s Laws An orbit that intersects the Earth’s orbit at one point and the other planet’s orbit at another point (on the opposite side of the Sun) Least Energy Orbit to Mars:  Least Energy Orbit to Mars Sun Earth Mars Spacecraft Orbit Time to get to Mars P2=a3 aEarth = 1 AU aMars =1.5 AU Time = = Spacecraft:  Spacecraft Types of spaces probes: Fly-by -- collects data as it passes by Example: Orbiter -- circle planet and study for a long time Example: Lander -- land on the planet and take samples Example: Next Time:  Next Time Read 15.1-15.4 , 6.7 Quiz #1 on Monday Study hard! Summary:  Summary Refracting Telescopes use a lens to bend light to a focus Reflecting Telescopes use a mirror to reflect light to a focus Most large research telescopes are reflectors Astronomers today record and analyze data digitally Summary:  Summary To observe the entire electromagnetic spectrum you need many different types of telescopes, some of them in space Spacecraft have allowed close up study of the planets Spacecraft reach their destinations by using the gravity of the Sun (or sometimes planets)

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October 24, 2017

October 24, 2017

October 24, 2017

October 24, 2017

October 24, 2017

October 24, 2017

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