Radio Astronomers

Q: How many radio astronomers does it take to change a light bulb.
A: None. They aren't interested in that short wave stuff.

How Many Politicians Does it take to Change a Lightbulb?

Q: How many politicians does it take to change a light bulb?
A: Two. One to change it, and another one to change it back again.

Tenors And Light Bulbs

Q: How many tenors does it take to change a light bulb?
A: Six. One to do it, and five to say, "It's too high for him."