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

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 = wavesElectromagnetic 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 EffectThe 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

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