AstroCappella: Doppler Shifting

Music and Lyrics by Alan Smale

Susan cruisin' down the freeway doing seventy-eight
        (go speed racing, go speed racing)
She just likes to drive fast, it's not that she's late
        (no tail-gating, no tail gating)
Goes over a hilltop and what a surprise
        (too late sister, you're in for it now)
Blue and red flashing lights right in front of her eyes
Nee nee nee nee nee nee nah nah nah nah nah nah nah nah
Now Susan's standing by the side of her car
        (show me your licence, you're in big trouble)
Trucks blowing right by her but she's not going far
        (they're still cruisin', Susan's losin')
She's been caught by a speed trap, and now she can hear
        (here comes the physics, you're in for it now)
Sound of the Doppler Shift right in her ear


That's the Doppler Shift - you've heard it I know
Doppler Shift - first it's high then it's low
The good cop's gun shoots out only radar

And the beam bounces back off bad Susan's car
And assuming the policeman is standing in range
His gun tells him all about the frequency change
Then Susan's walking, walking
Her speed racing days are done

They're light years away, man, and that's pretty far
        (lightspeed's the limit, the big speed limit)
But there's plenty we can learn from the light of a star
        (split it with a prism, there's little lines in it)
By looking at the spectrum at the light that's glowing
        (wavelengths of emission, measured with precision)
Its Doppler Shift will tell us if it's coming or going
Doo doo doo doo doo-ooo 

That's the Doppler Shift - you see it, it's true
Doppler Shift - to the red or the blue
When a star is approaching and it's coming our way
Its spectrum seems bluer, won't you hear what I say
And when a star's retreating way out of range
And the scientist measures its frequency change
Well that's a redshift, redshift
If the star is moving away

By reading Doppler Shifts of all we see in the skies
        (clusters of galaxies, near and far)
We get the big picture and a big surprise
        (redshifts going, redshifts going)
The Universe is growing and expanding away
        (galaxies are speeding, speeding away)
But maybe gravity will shrink it back some day
Doppler Shift - to the red or the blue
Doppler Shift - and our shift's overdue

Now blueshifts come and redshifts go
And that's pretty much everything you need to know
Now we're gonna pick up Susan and give her a ride
So you guys remember Doppler, and you drive to survive
And now we're shifting, shifting
And our Doppler song is done