interference from television static
pigeon poop on the telescope
torn wiring
Correct!
The radio telescope was able to pick up the mysterious radiation because it could detect longer wavelengths.
cosmic microwave background
In 1964, two astronomers at Bell Labs in New Jersey started testing a horn-shaped radio antenna. They encountered a "noise" they couldn't explain, a low-level energy, coming from all directions in the sky. The energy turned out to be the oldest light ever seen—light from just after the big bang, 13.8 billion years ago. This glow came to be called the cosmic microwave background.