Today

LQG5r TIL scientists have been able to trace the start of HIV/AIDS to King Leopold’s Belgian Congo, originating as far back as 1909. The first person to be infected probably got the virus in the 1920s
grbXL TIL ‘Cummingtonite’ and was named after the town of Cummington, Massachusetts, where it was discovered in 1824.
0dxXy TIL that at an inventors' luncheon in October 1912, 24-year-old Madeleine Edison, the daughter of Thomas Edison, referred to Nikola Tesla as "our dear friend" and "the largest man I've ever seen", with Tesla standing at 6'2" tall. She described Tesla's interest in her, but she was already engaged.
j6bAn TIL researchers discovered that a single 2×2 LEGO brick can handle 950 pounds of force in a hydraulic press before breaking
M7p1m TIL Purple cabbage can be used to create a liquid that changes colors; Red, Violet, Blue, Green and Yellow depending on pH level. This is an experiment you can easily try yourself with household materials.
5VR98 TIL only 3 countries don’t use feet for flight levels (the altitude a plane flies at): China, Mongolia, and North Korea. Russia and Tajikistan use a blended system of metric at lower altitudes.
x6njg TIL that before the moon landing, the US landed 7 unmanned Surveyor missions, with Surveyor 3 landing in the Ocean of Storms. 2 years later Apollo 12 landed in the same spot and the astronauts walked over and took its picture.
4kWnJ TIL as a joke about the historic rivalry between Sweden and Denmark, the only IKEA products named in Danish are doormats and other things you walk on
nWMaP TIL in 1937 a natural gas leak caused a school to explode in Texas, killing at least 295 people. Witnesses described seeing the walls bulge and the roof lifting off the building before it collapsed.
9wX6X TIL that 30% of adults and up to 40% of children grind or clench their teeth at night, this condition is linked not only to worn-down teeth, but also to anxiety, depression, Tmj and many more.
W7bQA TIL the experimental ‘Sprint’ anti-ballistic missile went 0 to Mach 10 in only 5 seconds, w 650,000 lbs thrust on a 7,500-lb body. For comparison, a Minuteman III ICBM makes ~200,000 lbs thrust despite weighing >10× more, and a Boeing 747-8 maxes @ ~266,000 lbs while weighing >100× more than Sprint.
R5yNQ TIL the Paraguayan War (1864–1870) was so devastating that it wiped out 60–70% of the country's entire population, and is listed in the Guinness World Records for the highest proportional death toll from war for any single country.