Transcript Slide 1
Energy From Space • Almost all of the energy in the universe comes from stars • Stars are powered by nuclear fusion: joining together (“fusing”) the nuclei of two atoms Nuclear Fusion • Involves the very smallest atoms (Hydrogen and Helium) • Hydrogen nuclei are joined together to form a Helium nucleus • Two isotopes of Hydrogen (left) fuse together to form one nucleus of Helium (right) Fusion Energy • Nuclear fusion releases large amounts of energy • Modern nuclear weapons rely on fusion reactions • In our sun, about four million tons of matter is converted to energy every second Fusion Video • Stars release many types of energy (besides heat and light) • All types of energy from stars is called Electromagnetic Radiation (“E.M.R.”) E.M.R. = all types of energy that travels through space in waves • Different kinds of EMR have different wavelengths • Wavelength = distance from the crest of one wave to the next Speed of EMR • All E.M.R. travels at the “speed of light” = 300,000 kilometers per second (km/sec) • Light Year = the distance light travels in one year = 9.5 trillion kilometers Electromagnetic Spectrum Forms of Electromagnetic Radiation (EMR) A Quick Tour of the Electromagnetic Spectrum Note-taking: for each type of radiation, describe: • Where it lies on the EMS (wavelength) • How humans use it • How it affects us (or other life forms) NASA: Electromagnetic Spectrum Basics (30:35) 1. Radio Waves Longest wavelengths Used for communication Astronomers use radio telescopes Very Large Array (VLA) Used for “listening-in” to deep space Radio Wave Imagery Radio (red) and X-Ray (green) image of the center of the Milky Way Radar Imagery (radio detecting and ranging) 2. Microwaves Used for communication (cell phones) Microwave Imaging Satellite Microwave Imagery 3. Infrared Imagery Often used to detect heat differences (thermal imaging) Used for night-vision Infrared is used in Weather Forecasting Infrared helps astronomers to find the temperature of objects in space Infrared image of a nebula in Sagitarius Some reptiles (pit vipers) can “see” in infrared 4. Visible Spectrum Astronomer use optical telescopes to view images of space Refracting telescopes use lenses to magnify images Reflecting telescopes use curved mirrors to magnify images 5. Ultraviolet radiation • Wavelengths too short for humans to see • Causes sunburn and skin cancer • Some insects (ex. bees) can see ultraviolet Ultraviolet Flower Images Appearance in visible light Appearance in ultraviolet light Ultraviolet Flower Images Appearance in visible light Appearance in ultraviolet light Ultraviolet Flower Images Appearance in visible light Appearance in ultraviolet light (ultraviolet radiation) Used in “blacklights” and fluorescent lights Fluorescent pigments will produce their own light (glow) when struck by UV light. 6. X-Rays Used in medicine Long exposure to X-rays is dangerous to humans Astronomer use X-ray telescopes to find unusual features in the universe Chandra X-Ray Telescope X-ray image of a supernova remnant in the Large Magellenic Cloud X-ray emission from black hole in Cygnus 7. Gamma Rays • • • • Shortest wavelengths Highest energy Released by nuclear reactions Very dangerous to humans Gamma ray bursts from supernova remnant A spectrascope separates a light beam into its various colors (spectrum) Not all “rainbows” are the same! Different elements produce different spectra (rainbows) when they emit light: • Colors produced by individual elements are called emission spectra Emission spectra of individual elements are “pieces” of the visible spectrum: Entire visible spectrum Sodium Mercury Hydrogen Helium Spectrometers use emission spectra to determine the elements in a substance The spectra from stars and nebulae can be analyzed to determine the elements they contain