Notices by Robert McNees (mcnees@mastodon.social)

Danish physicist Niels Bohr was born #OTD in 1885.

Bohr applied the nascent quantum theory to the structure of the Hydrogen atom, offering an explanation (though not a true mechanism) for an outstanding problem that classical physics could not account for.

Image: Atomic Heritage Foundation

Astrophysicist Charlotte Moore Sitterly was born #OTD in 1898.

She compiled extensive data on optical and later UV spectra, and her spectroscopic tables are still in use today.

Image: AIP Emilio Segrè Visual Archives / Michael A. Duncan

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

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.)

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

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

A remarkable video of the Triton fly-by, made in 2014 with restored/processed Voyager 2 images.

Credit: P. Schenk, LPI / NASA / JPL

https://youtu.be/N1Fl1QKkEok?si=5Gzct_dJNkuiT-oz

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:

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.

Astronomer Vera Rubin was born #OTD in 1928.

Her work on galactic rotation curves became one of the main pieces of evidence for the existence of dark matter, and she deserved a Nobel Prize for it.

Image: Vassar College / Emilio Segrè Visual Archives

Astrophysicist Jocelyn Bell Burnell was born #OTD in 1943. As a grad student at Cambridge in 1967, she discovered an entirely new type of celestial object: Pulsars!

Photo: National Science & Media Museum / Science & Society Picture Library

The last moonwalk began #OTD in 1972.

No one has set foot on the Moon since Apollo 17 astronauts Eugene Cernan and Harrison Schmitt, 50 years ago today.

Images: NASA

Jocelyn Bell Burnell transformed astronomy #OTD in 1967 when she made the first observation of a pulsar.

She and advisor Antony Hewish initially dubbed the object LGM-1 (“Little Green Men”) for its regular signal, but soon identified it as a rotating, magnetized neutron star.

#astronomy #pulsars #neutronstars #JocelynBellBurnell