Tootfinder

Ten years (!) ago #OTD the first - and shockingly clear - #GravitationalWave signal was seen by the two LIGO detectors ... rumors flew immediately but the official announcement came only in February 2016: https://telescoper.blog/2025/09/14/a-decade-of-gravitational-waves/ and a lot more in https://ligo.org/wp-content/uploads/2025/09/LIGO-magazine-issue27.pdf plus a long article from back then in https://cplberry.com/2016/02/11/gw150914/ and a 1-1/2-hour documentary at https://www.youtube.com/watch?v=dX4vCNi544w

#OTD in 1937, Alan Turing’s paper ‘On Computable Numbers with an Application to the Entscheidungsproblem’ was published: https://people.math.ethz.ch/~halorenz/4students/Litera…

#OTD 2022.

#OTD: 13 years ago, I visited the Mercedes-Benz Museum in Stuttgart.
It is one of Germany's temples to “das Auto”. Architectural gems, this one is by UN Studio.

Mathematician Karen Keskulla Uhlenbeck was born #OTD in 1942.
She is known for her work on PDEs, calculus of variations, topology, and gauge theory, and was the second woman (after Emmy Noether!) to give the plenary lecture to the International Congress of Mathematicians.

Robert McNees (@mcnees.bsky.social)
Mathematician Karen Keskulla Uhlenbeck was born #OTD in 1942. She is known for her work on PDEs, calculus of variations, topology, and gauge theory, and was the second woman (after Emmy Noether!) to give the plenary lecture to the International Congress of Mathematicians. 👩‍🔬 🧪

#OTD 4 years ago.

This is a picture I took on this exact day 14 years ago. It shows compact electric vehicles for shared mobility in Berlin, Germany. The future was here — where did it go?
#OTD #EV

60 years ago #OTD (or tomorrow) #comet #IkeyaSeki showed a dramatic tail: https://solarviews.com/cap/comet/ikeya.htm - and this chemical 'raw' picture proves it beyond doubt ... while nowadays creepy 'astrophotographers' past high-end stacks of the faint tails of comet Lemmon into landscape pictures creating similar "photographs" which then get likes galore. Sigh ...

63 years ago, on the 27th of September 1962,
Rachel Carson's book Silent Spring was published.
It handled the environmental harm caused by the pesticide DDT
and the disinformation spread by the chemical industry.
Carson managed to sway public opinion and even policy.
#otd #history 🗃️

35 years ago #OTD the #Hubble Space Telescope with its mishappen optics took this image of #Saturn - which could be sharpened a lot mathematically (as the paper https://articles.adsabs.harvard.edu/full/1991ApJ...369L..51W later described) since the object was so bright. It's being said that this one image was used by NASA to convince key U.S. politicians that the broken satellite still had some life in it ... and so it was, for 35 years now!

De compagnie van Frans Banninck Cocq
🎗️
📷 #OTD 2024

30 years ago #OTD I was in #India to observe a Total #SolarEclipse lasting under a minute in Neem Ka Thana, Rajasthan: my report on the whole trip to this amazing country - written originally for an English magazine - can be found at https://geocities.restorativland.org/CapeCanaveral/5599/india_95_story.html while the picture here was taken by Voyto Rušin at the same observing camp and processed by Miloslav Druckmüller: http://www.zam.fme.vutbr.cz/~druck/eclipse/Ecl1995i/0-info.htm

60 years ago #OTD #comet #IkeyaSeki reached perihelion, -10 mag., was visible in daylight and showed a spectacular tail in the following weeks: https://groups.io/g/comets-ml/message/32770 and https://www.astronomy.com/today-in-the-history-of-astronomy/sept-18-1965-discovery-of-comet-ikeya-seki/ and https://noirlab.edu/public/images/noao-01854/

#OTD in 2007 op de Domtoren, richting station #Utrecht CS. Ter vergelijking een latere foto (2 juni 2022 ter gelegenheid van 900 jaar stadsrechten)

#OTD 2014: spending the night at the #Bauhaus in Dessau