Light and Telescopes

A Telescopes is a tool used to gather light from objects in the universe

Tool Websters: Tool- something (as an instrument or apparatus) used in performing an operation or necessary in the practice of a vocation or profession From the Urban Dictionary: Tool - One who lacks the mental capacity to know he is being used. A fool. A cretin. Characterized by low intelligence and/or self-steem.

There are two different types of telescopes A refracting telescope uses a glass lens to concentrate incoming light A reflecting telescope uses mirrors to concentrate incoming starlight

A refracting telescope uses a lens to concentrate incoming light

Reflecting telescopes use mirrors to concentrate incoming starlight

Three main functions of a telescope Most important!! Gather More Light – (bigger Is better) making objects appear brighter followed by to see fine detail (called resolution) and least important, magnify magnification = (objective lens focal length / eyepiece lens focal length)

A larger objective lens provides a brighter (not bigger) image

If you pass white light through a prism, it separates into its component colors. long wavelengths ROY G B I V short wavelengths spectrum

But visible light is only one type of electromagnetic radiation (light) emitted by stars Astronomers are truly interested in the entire spectrum of Light!

Consider This Class as Seen in Different Wavelengths of Light!

Consider Orion as Seen in Different Wavelengths of Light!

Observations at other wavelengths are revealing previously invisible sights UV infrared Map of Orion region Ordinary visible

Hubble Space Telescope Views of Orion Nebula showing stars hidden in clouds http://oposite.stsci.edu/pubinfo/pr/97/13/A.html

TODAY’S Sun as seen in visible light from Earth and from space in X-rays by satellites http://solar.physics.montana.edu/tslater/real-time/

Radio wavelength observations are possible from Earth’s surface

The Very Large Array (VLA) in New Mexico

Earth’s atmosphere hinders astronomical research Image of stars taken with a telescope on the Earth’s surface Same picture taken with Hubble Space Telescope high above Earth’s blurring atmosphere

High above Earth’s atmosphere, the Hubble Space Telescope provides stunning details about the universe

Astronomers use different instruments to look at light of different wavelengths - sometimes, we even have to go above Earth’s atmosphere.

Not all EM radiation can penetrate Earth’s atmosphere.

Why do stars twinkle, but planets seemingly do not?

Differences in the temperature and density of small portions of Earth’s atmosphere cause passing starlight to quickly change direction, making stars appear to twinkle.