Doppler shift

DOPPLER EFFECT/SHIFT

Doppler shift

Allows astronomers to measure the direction of movement of stars and galaxies in relation to Earth.

 1 No shift in the spectral lines: The galaxy is at rest 2 A shift toward the red: The galaxy is moving away. 3 A shift toward the blue: The galaxy is approaching Earth.

And…..the images from the different types of telescopes look very different!

The images look very differentUltraviolet

Infrared

NGC1512 barred spiralgalaxy

HST images

The images look very different

M87 giant elliptical galaxy in Virgo cluster

The images look very different

red=xraygreen=opticalblue=UV

30 DoradusOpen cluster in LMC

Spectrographs

We don’t always want to make an image Sometimes, we want to split the light into its

spectrum We use spectrographs for this

Spectrographs

There are two basic types of spectrographs Prisms Gratings

Combining the two, we get Grisms

Prisms

Prisms

Prisms work because light of different wavelengths takes a slightly different path

Comes out at a different place, and is thus spread out

Gratings

Gratings

Gratings are made up of hundreds or thousands of tiny grooves

They use a phenomenon of light known as diffraction to split the light