Depending on your time zone, Voyager 2's closest approach to Neptune was either yesterday (the 24th) or #OTD in 1989. It took place around 4am UTC.
Here's a short thread with some great images captured by the probe, and some proposed cargo for a future mission. #ReturnToNeptune
(Definitely read this one to the end.)
Voyager 2 captured this image of Neptune's Great Dark Spot on its approach to the planet a few days earlier.
But when Hubble looked just five years later, the Earth-sized storm with 1300 mph winds was gone.
Image: NASA/JPL
Images of Neptune’s moon Triton and its surface captured by Voyager 2 as it sailed past.
Of all the large objects in the solar system, Triton has the most circular orbit. The eccentricity is only about 0.00002.
Images: NASA / JPL
A remarkable video of the Triton fly-by, made in 2014 with restored/processed Voyager 2 images.
Credit: P. Schenk, LPI / NASA / JPL
Three days after its flyby, Voyager 2 looked back for this gorgeous image of a crescent Neptune and Triton. Triton, much smaller than Neptune, is in the foreground.
Image: NASA/JPL
Voyager 2 continued to collect Neptune data for another month or so after sailing off. But this was the last stop on its Grand Tour. After that, it left the ecliptic and headed off towards interstellar space.
We haven't been back since.
However, if NASA *does* decide to send another probe, there's a little bit of cargo I'd like to add.
When my daughter was 6yo, she figured out that thing where you sneakily stick a note on someone’s back.
But she didn’t know the notes should say things like “kick me.” Instead, she would put space facts on them. She was really into outer space at the time.
One time I felt something on my back, then heard her run off giggling. I reached around, peeled off the little post-it, and found this:
@mcnees It was so cool when Voyager went by Neptune. The only drag was my dad had died of cancer earlier in the month. First cool astronomy thing I couldn’t share with my dad.
RIP dad.
@glasspusher Ah, I'm so sorry.
@mcnees yeah so it goes. Have lots of great shared astronomy memories with him, though. When I was in middle school and got my first telescope, I showed him sunspots and he was so thrilled he kept a notebook on them every day he could see the sun for a year.