Neptune, 25 Years Ago Tonight

On August 25, 1989, I was in the observatory at Villanova University taking data with the astronomy department’s 15-inch telescope. The telescope was doing it’s thing – measuring the shift in brightness of a binary star system as one star eclipsed its companion hundreds of light-years away. It wasn’t exceptionally difficult work – you boot up the computer, point the telescope to its target, turn on the photometer and let the photons come trickling in. In a roll-off roof observatory, I had the entire night sky to gaze upon, which I typically did during those long observations.

But on this night, my attention was turned toward a television set I brought into the observatory. I turned the brightness almost all the way down, and tuned to WHYY, the local PBS station serving the greater Philadelphia area. I never watched TV while observing before, but tonight Voyager 2 was making its closest approach to Neptune, and I was going to see it live.

The broadcast was billed as “Neptune All Night” – a live, real-time telecast as Voyager 2 made it’s closest approach 5,000 miles above Neptune’s cloud tops. From midnight until 7am, I watched image after raw, grainy image appear on the screen revealing an alien world as seen by the spacecraft as it flew by at 42,000 miles per hour.

Neptune, as seen by Voyager 2 on August 25, 1989. It didn't look like this on the TV screen.
Neptune, as seen by Voyager 2 on August 25, 1989. It didn’t look like this on the TV screen. Image credit: NASA/JPL

During the broadcast, a panel of astronomers from the Franklin Institute, the University of Pennsylvania, and even a science fiction writer commented on the images as they were coming in.

Clearly, there were millions of people watching. I’m sure there were watch parties in people’s homes, universities, and of course at JPL, where the mission was being run and was the primary broadcast center for the evening’s flyby. Throughout the evening, people would call in asking questions the experts did their best to answer.

Intro to Neptune All Night – WHYY Philadelphia

But standing there, alone in the dark, it felt at times that it was just Neptune, Voyager, and myself. I often looked up from the TV toward the southwest sky, where, 2.7 billion miles from earth, our robotic emissary was transmitting these images.

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Simulation of sky from Philadelphia on the morning of August 26, 1989. Source: Starry Night College.

As Neptune set in the southwest, the encounter was coming to an end. Toward the east, the sky was lightening and the Sun would be up soon. I ended the observation, closed up the telescope, shut down the computers, and closed the roof.

And Voyager 2 sped on into the night.