Thorium is a chemical element with symbol Th and atomic number 90. A reactive actinide metal, its chemistry is dominated by the +4 oxidation state; it is silvery and tarnishes black in air, forming the dioxide. It is malleable and moderately hard, with a high melting point. Its most stable isotope, ²³²Th, is weakly radioactive with a half-life of 14.05 billion years, roughly the age of the universe: it decays very slowly to stable lead. Thorium and uranium are the only two significantly radioactive primordial elements. Thorium is chiefly refined from monazite sands as a byproduct of extracting rare earth metals. It was discovered in 1829 by the Norwegian mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder. Applications were found for the element in the 19th century, but after its radioactivity was discovered in the early 20th century, its use significantly declined. Thorium has been suggested as a replacement for uranium in nuclear reactors. ( Full article...)

Monkey beetle on Romulea monadelpha

• ... that the flower of Romulea monadelpha is pollinated by a species of monkey beetle (both pictured)?
• ... that Alysia Rissling was the pilot for the first ever all-woman team in an official four-man bobsleigh race after the event became gender neutral?
• ... that the Neues Bachisches Collegium Musicum was founded in 1979 by Max Pommer and members of the Gewandhausorchester after Bach's model?
• ... that the British dentist Neil Swallow often made night calls to make feeding plates for babies born with cleft palates?
• ... that until it closed in 2009, J.E. Rhoads & Sons was the longest continually-operating company in the United States, having been in business for more than three centuries?
• ... that after failing to get playing time at ABC Futebol Clube, footballer Rodriguinho Marinho considered becoming a futsal player?
• ... that the 2010 Infrastructure Cost Review led to annual savings of £3 billion in British government expenditure on infrastructure by 2014?
• ... that the Comet Ping Pong pizzeria's name comes from a sign that one of the co-founders discovered at a liquor shop?

Aftermath of the Baku clinic fire

• At least 25 people die in a fire (aftermath pictured) at a drug rehabilitation clinic in Baku, Azerbaijan.
• Attacks at multiple locations in Ouagadougou, Burkina Faso, leave at least 28 people dead and 50 others injured.
• At least 31 people are killed and about 300 others are injured by an earthquake in Papua New Guinea.
• American evangelical preacher Billy Graham dies at the age of 99.
• Three Billboards Outside Ebbing, Missouri wins five awards, including Best Film, at the British Academy Film Awards.

March 5: Learn From Lei Feng Day in China

Sinclair ZX81

• 363 – Roman emperor Julian and his army set out from Antioch to attack the Sassanian Empire.
• 1824 – The First Anglo-Burmese War, the longest and most expensive war in British Indian history, began.
• 1943 – The Gloster Meteor, the first operational jet fighter for the Allied Powers, made its maiden flight.
• 1963 – Country music stars Patsy Cline, Cowboy Copas, and Hawkshaw Hawkins were killed when their Piper PA-24 Comanche crashed shortly after takeoff in Camden, Tennessee, U.S.
• 1981 – The ZX81 (pictured), a pioneering British home computer, was launched by Sinclair Research and went on to sell over 1.5 million units around the world.

Gerardus Mercator (b. 1512) · Marietta Piccolomini (b. 1834) · Lena Baker (d. 1945)