Astronomy Big Idea: The sun is one of billions of stars in one of billions of galaxies in the universe.

Observing the Universe EQ: What can we learn from space images?

Astronomy - the study of stars What characteristics might we learn about when we are studying astronomy (or the stars)?

Stars Huge spheres of hot, glowing gas Example = sun Stars give off energy – how do we know this?

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

Energy = waves Electromagnetic spectrum all of the frequencies or wavelengths of electromagnetic radiation

Telescopes Use lenses or mirrors to collect and focus light energy from distant objects Three different types: Refracting telescope Reflecting telescope Radio telescope Both of these are visible light telescopes= OPTICAL

Refracting telescope Uses lenses to gather and focus light

Reflecting Telescope Uses mirrors to gather and focus light

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

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, temperatures, and motion

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.

What elements does this star contain?

Temperature of stars Color of a star reveals its temperature. 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)

The temperature and composition of stars https://www.youtube.com/watch?v=01U7ZUKVW8o

Doppler Effect The Doppler effect says that things moving away from you look redder than they would if they weren’t moving. Things moving towards you look more blue.

Doppler Effect The change in wavelength of a moving object Red Shift – objects moving away from observer Blue Shift – objects moving toward observer

Telescopes: Similarities and Differences Traits which are only true of reflecting telescopes Traits which are only true of refracting telescopes Traits which are only true of radio telescopes