- Binary Star § Astrometric binaries (Wikipedia)
Astronomers have discovered some stars that seemingly orbit around an empty space. Astrometric binaries are relatively nearby stars which can be seen to wobble around a point in space, with no visible companion. The same mathematics used for ordinary binaries can be applied to infer the mass of the missing companion. The companion could be very dim, so that it is currently undetectable or masked by the glare of its primary, or it could be an object that emits little or no electromagnetic radiation, for example a neutron star.
- Czechoslovakia (Wikipedia)
Czechoslovakia (/ˌtʃɛkoʊsloʊˈvæki.ə, ˈtʃɛkə-, -slə-, -ˈvɑː-/ CHEK-oh-sloh-VAK-ee-ə, CHEK-ə-, -slə-, -VAH-; Czech and Slovak: Československo, English lit. Czechiaslovakia) was a country in Central Europe created in 1918, as Czecho-Slovakia (until 1920), when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland became part of Nazi Germany. Between 1939 and 1945, the state ceased to exist, as Slovakia proclaimed its independence and Carpathian Ruthenia became part of Hungary, while the German Protectorate of Bohemia and Moravia was proclaimed in the remainder of the Czech Lands. In 1939, after the outbreak of World War II, former Czechoslovak president Edvard Beneš formed a government-in-exile and sought recognition from the Allies.
