astronomy
DESCRIPTION
Astronomy. - the study of stars. Stars. Huge spheres of hot, glowing gas Example = sun Stars give off energy---how do we know this?. Energy = waves Electromagnetic spectrum. Huge spheres of hot, glowing gas Example = sun Stars give off energy---how do we know this? - PowerPoint PPT PresentationTRANSCRIPT
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Astronomy-the study of stars
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Stars• Huge spheres of hot, glowing gas
– Example = sun
• Stars give off energy---how do we know this?
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Energy = wavesElectromagnetic spectrum
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• Huge spheres of hot, glowing gas– Example = sun
• Stars give off energy---how do we know this?– Visible light = we can see lots of stars in the
sky– Radiant energy from the sun heats the earth– Also, some stars give off radio waves
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Telescopes
• Use lenses or mirrors to collect and focus light from distant objects
• Three different types:– Refracting telescope– Reflecting telescope– Radio telescope
Both of these are visible light telescopes
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Refracting telescope
• Consists of 2 convex lenses– First lens (objective lens) gathers the light and
focuses it– Second lens (eyepiece lens) magnifies it
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Reflecting Telescope
• Uses a concave mirror to gather and focus light
• A smaller mirror inside reflects this image to the eyepiece lens which magnifies it
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Radio Telescope
• Detects radio waves given off by objects in space
• Most have curved reflecting surfaces that are several hundred meters in diameter
• The bigger the radio telescope, the more radio waves it can collect
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Traits which are only true of reflecting telescopes
Traits which are only true of refracting telescopes
Traits which are only true of radio telescopes
Telescopes: Similarities and Differences
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Spectroscopes
• Also called a spectrograph
– Breaks the light from an object into its color spectrum
– Astronomers use this to get information about stars including their chemical compositions and temperatures
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Spectroscopes: star’s chemical composition
• What elements is a star made up of?
• Astronomers compare the banding patterns of known elements to those of the stars.
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What elements does this star contain?
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What makes up the universe?
• On the right side of your paper, list as many things as you can come up with in one minute.
• Stars, galaxies, star systems, nebulae, etc.
• Universe = space and everything in it!
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Review: What is a star?
• A star is a huge sphere of hot, glowing gas.
• Can you think of any examples of stars? – The sun is a star!
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Stars
• What pieces of equipment can be used to gain information about stars?– Reflecting telescope– Refracting telescope– Radio telescope– SPECTROSCOPE!!
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What is a galaxy?
• A galaxy is a cluster of stars.
• Billions of stars make up a galaxy.
Can you think of the name of our galaxy?– Milky Way galaxy
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How do we measure distance to stars and other galaxies?
• We have to use a unit called a light year.
• A light year is the distance light can travel in one year….HUGE!
• light year is a unit of distance, not time!!!!
• 1 light year= ~9.5 million million kilometers
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Parallax
• Parallax is the apparent change in position of an object when you look at it from different places.
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What characteristics classify stars?
• All stars are huge spheres of glowing gas (mostly hydrogen).
• Stars are classified based on 3 main physical characteristics:– Temperature– Brightness– size
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LAB: Color vs. Temperature
• You will record the data for your lab in your Cornell notes on the RIGHT side.
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Summary of Lab Findings
• On the right side, place the order of star color by increasing temperature
For example:
Coolest colornext colordsfsjsdhfjkhottest color
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Temperature of stars
• Color of a star reveals its temperature.
• Remember the color vs. temperature lab?– Red stars = relatively cool stars (still hot
~3200 degrees Celsius)– Yellow- white = medium temperature (~5500
degrees Celsius)– Blue-white stars = hottest stars (>10,000
degrees Celsius)
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Brightness of stars
• Brightness = the amount of light stars give off– This depends on its size and temperature– How bright it looks from Earth depends on
distance and actual brightness• Apparent magnitude• Absolute magnitude
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Apparent Magnitude
• Brightness as seen from Earth
• Example: the sun looks very bright to us on Earth, but it is not the brightest star– It looks brighter because it is closer to earth
than other stars.
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Absolute Magnitude
• Brightness of a star if it were a standard distance from the earth
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Review
• What characteristics are used to classify stars?
• Now, we will look at graphs that show these characteristics of stars…they are called HR diagrams
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Hertzsprung – Russell Diagram
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