This is an excellent book for laypeople about the Cosmic Background Explorer (COBE) satellite, and its discovery of ripples in the radiation from the Big Bang.
Electrons jiggling around generate radio waves. Temperature is just a measure of the average speed with which the atoms of a body are moving, vibrating and spinning. So any body, at any temperature above absolute zero, emits radio waves. Cool!
Why tell you this? Well, when they say the Background radiation is at a temperature of 3 degrees what they mean is, it's of the type of radiowaves that are emitted by a body at a temperature of 3 degrees.
-- and that's something I didn't know, before I read the book.
It's the least of what you'll get:
1. You get a history of the theory.
2. Details about radioastronomy, and how astronomers work around their problems (since everything -- the ground, the air, the dust in the galaxy, the cables on a balloon carrying a detector -- glows with radio waves, it's a bit tricky seeing the backround radiation of the Big Bang)
3. Peeks into how science works: you propose a theory, and then chuck it if it doesn't fit the data, except that sometimes it's the data that's at fault not the theory
4. The importance of confirming your results, so that scientific discovery's a community effort despite all the pushing to get there first
5. The importance of looking at all the ramifications of a theory: gas clouds in interstellar space are warmed by the background radiation, and people measured their temperature, and wondered why they weren't stone cold, long before the radiation itself was observed
6. Why that famous photo of pink and blue patches is both the truth and not
7. Interesting tidbits on cosmology
8. the personalities involved
... and more, and more, in only 170 pages.
Students doing London A Level Astrophysics will find this an exceedingly useful read. (Though no mathematical equations at all, you get a load of physics, painlessly)
And to top it all, some neat rhetoric:
" ... COBE had reached its orbit 900 kilometres above the Earth. It was now circling the Earth every 72 seconds as it turned on its axis. It could be seen in the night sky, going from south to north a little after sunset, or from north to south a little before dawn.
COBE awakened, opening its eyes to the microwave Universe. "
The bit at the end's the best, though.
Read, enjoy, learn.