How do I start Echoes of the Eye after finding the radio tower?

After purchasing the Echoes of the Eye DLC for Outer Wilds, a new museum exhibit was added showing a radio tower and a deep space satellite. I found the radio tower and the satellite, but I can't figure out what to do next to start the DLC.

The radio tower had photos taken by the satellite and an audio log of someone observing something "impossible" in one of the photos. One of the photos shows a person blocking the lens, but talking to Gabbro reveals that was them inspecting the satellite after Hornfels sent them. Visiting the satellite, I found an audio log from Gabbro confirming there were no defects. I can't find anything unusual in the photos aside from Gabbro, and talking to Hornfels doesn't let me ask them about the pictures.

What am I supposed to do after finding the radio tower and satellite?

Figured it out. As to not completely spoil the puzzle, below are some hints for what to do after finding the radio tower. The direct answer is at the bottom.

Hint 1:

The person in the audio log thought the lens was smudged.

Hint 2:

The unusual photo is not the one with the person blocking the lens.

Hint 3:

Pay attention to the sun.

Hint 4:

Try observing from the satellite for a while.

Difference in the photos:

There is a black spot partially eclipsing the sun in the photo at 40 degrees.

How to access DLC area:

Open the map and set a target for the deep space satellite orbiting vertically around the solar system. Fly out to the satellite, observe the sun, and wait. When the camera is around 30 degrees, you should see a black spot obscuring the sun. Fly straight towards the black spot.