So these deep space satellites that go and take pictures, how are they getting the picture back to the earth. Assuming they use radio waves, how long after the picture is taken do we usually get the picture? Something I was just pondering.

Yes, they use radio waves, and how long it takes to piece together the picture depends on the "bandwidth" of the broadcast, which controls how fast it can transport information. For example, when the Galileo spacecraft lost function in its main antenna, it had to send its pictures back painfully slowly, but it still managed to conduct a lot of good science.

It is likely that some future spacecraft will use lasers for data communication, but so far it has pretty much been all radio. As to how long it takes, that depends on the spacecraft, the route it takes to transmit the image, and what you mean by "we". Some piece of equipment on Earth gets the image in some form when it arrives. Images are usually stored on the spacecraft and transmitted later. Once sent from Jupiter take 30 to 50 minutes to get here. Images from the Mars Rovers may take longer because they are transmitted to an orbiter and stored there for a while and retransmitted.

It often takes the general public longer to get the image because they need to get processed, and because some images belong to researchers who don't share them immediately.

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