Chapter 21 Stars, Galaxies, and the Universe

 How do we study other stars in our galaxy if they are so far away?  We study the radiation that stars emit to find out more about them. Intro- duction

 Energy that can travel through space is called electromagnetic radiation.  Electromagnetic radiation can travel through empty space and travels in waves.  Electromagnetic radiation travels the speed of light. Electro- magnetic Spectrum

Electro- magnetic Spectrum Picture From:

 The electromagnetic spectrum is the full range of wavelengths of electromagnetic radiation. Electro- magnetic Spectrum

Diagram From: saturn.jpl.nasa.gov/mission/nav-uplink.cfm

Diagram From:

RADIO WAVES  Longest waves and less frequent than other waves.  Used for communication.  Radio telescopes used to collect radio waves.  Size of wave ranges from the size of a football field to the size of a football. Electro- magnetic Spectrum

MICROWAVES  Used in communication, weather maps, and as a heat source.  Size of wave ranges from 1 foot to 1 centimeter. Electro- magnetic Spectrum

INFRARED WAVES  Used as a source of heat.  Infrared telescopes used to detect infrared waves.  Size of wave ranges from a few centimeters to a few millimeters. Electro- magnetic Spectrum

VISIBLE LIGHT  Only energy we can see with the naked eye.  Refracting and reflecting telescopes use visible light.  Size of wave is microscopic. Electro- magnetic Spectrum

VISIBLE LIGHT  White light can be separated into the 7 different colors of light.  ROYGBIV  Red, Orange, Yellow, Green, Blue, Indigo, Violet  Spectroscopes used to break white light down into different colors. Electro- magnetic Spectrum

ULTRAVIOLET WAVES  Energy that is partially blocked by our atmosphere.  Common uses are tanning beds, disinfection, and black lights.  A large amount of UV light is harmful for living things.  UV cameras and telescopes use UV rays.  Size of wave is a few molecules. Electro- magnetic Spectrum

X-RAYS  Atmosphere reflects all X-rays back into space.  Commonly used to take pictures of bones.  Very harmful to living things.  X-ray telescopes use X-rays.  Size of wave is one molecule. Electro- magnetic Spectrum

GAMMA WAVES  Shortest wave with the most energy.  Atmosphere blocks all gamma rays from entering.  Deadly to living things.  Used for medical treatment.  Gamma telescopes study deep space, black holes, stars, etc.  Size of wave is smaller than an atom. Electro- magnetic Spectrum

 Most telescopes collect and focus different types of electromagnetic radiation.  Two main types of telescopes: reflecting and refracting telescopes.  Refracting telescopes use lenses that bend light to focus onto a small area.  Reflecting telescopes use mirrors instead of lenses but still focuses light onto a small area. Telescopes

The Keck Telescopes: Located in Mauna Kea, Hawaii

Hale 200-inch Reflector: Located in Mt. Palomar, California

 A building that contains one or more telescopes is an observatory.  Most observatories are on mountaintops where images are less blurred because of the Earth’s atmosphere. Observat- ories

A giant telescope relies on multiple dishes - Located in Socorro, New Mexico

 The shorter electromagnetic radiation is blocked by the Earth’s atmosphere.  Telescopes are placed on satellites to detect these short, high energy waves.  Hubble Space Telescope – reflecting telescope that detects visible light, infrared, and UV radiation. Satellites

Hubble Space Telescope

Compton Gamma Ray Observatory

Chandra X-ray Observatory A telescope penetrates space with X-ray vision

Spitzer Space Telescope It will spend 2 ½ to 5 years studying infrared light.

 Most large telescopes have spectrographs.  A spectrograph breaks the light up into colors.  Spectrographs reveal information about stars like their composition and temperatures. Spectro- graphs

Electromagnetic Spectrum Video Clip: Electromagnetic Spectrum Video Clip