Final answer:
Radio waves provide images 24 hours a day quickly and cheaply.
Step-by-step explanation:
The radiation that gives images 24 hours a day quickly and cheaply is radio waves. Radio waves are the lowest-frequency and lowest-energy band of the spectrum, making them inexpensive to produce in large quantities. They can easily pass through Earth's atmosphere and are not significantly absorbed by interstellar dust and gas.
Additionally, radio waves are already extensively used for communications on Earth, further making them a suitable choice for providing images quickly and inexpensively.