After people started to record events, first by drawing symbols (called "pictographs") and then by writing, it became much easier to tell what happened, and history started. These records can tell us the names of leaders (such as Kings and Queens), important events like floods and wars, and the things people did in their daily lives. The time when "prehistory" ended and "history" started is different in different places, depending on when people began to write and if their records were kept safe or lost so they could be found later on. In places like Mesopotamia, China, and Ancient Egypt, things were recorded from very early times (around 3200 BC in Ancient Egypt) and these records can be looked at and studied. In New Guinea, the end of prehistory came much later, around 1900.
Early Middle Ages
The Roman Empire ruled much of Europe in ancient history. It became weaker and finally collapsed in 476. When it collapsed, its army stopped working and its communication systems (ways of people in different places talking to each other) also stopped working. This made the people in Europe unable to talk to each other and share news and facts. Because the Roman army had kept peace between different parts of Europe and defended it from other people, and the Roman army had now collapsed, there was much fighting. This time was known as the Dark Ages.
After the Dark Ages, there was the Middle Ages. It is called the "middle" ages because it was between ancient history and modern history. It can also be called medieval times. It was a time when Europe was Christian, and the Catholic Church was very powerful. The Middle Ages ended when the Renaissance started. During the Renaissance people began going to school and university more and learning more things. There was less fighting. The printing press was also made. This was a machine that made books easily and quickly. It made it easier for people to read and learn things.
Rome was sacked by Alaric, the leader of the Germanic tribe known as the Visigoths, in 410. This event weakened Rome and when in 476 Rome was invaded sacked again by Odoacer, he was able to take the city for himself and made himself the king of Italy. This event ended the Western Roman Empire.
KGB
KGB is the Russian-language abbreviation for State Security Committee. It was the main internal security agency for the Soviet Union from 1954 until its break-up in 1991. It was formed in 1954 as a successor of earlier agencies, the Cheka, NKGB, and MGB.
During the Cold War, the KGB suppressed "ideological subversion". This meant suppressing unorthodox political and religious ideas, and the people who held those ideas. It was Soviet policy for the KGB (and the secret services of the satellite states) to monitor public and private opinion, internal subversion and possible counter-revolutionary plots in the Soviet Bloc.
The KGB was instrumental in crushing the Hungarian Revolution of 1956, and the Prague Spring of "Socialism with a Human Face", in 1968 Czechoslovakia. A record of some of its doings is contained in the Mitrokin Archive.
From 13 March 1954 to 6 November 1991, KGB was the main name for the main Soviet security agency, intelligence agency or spy agency, and the secret police agency.
In March 1953, Lavrenty Beria merged the MVD and the MGB into one agencythe MVD. In December of that year, Beria and six associates were executed and the MVD split. The re-formed MVD retained its police and law enforcement powers, while the second, new agency, the KGB, did the internal and external security functions, and reported to the Council of Ministers.
On 5 July 1978 the KGB was renamed as the "KGB of the Soviet Union", with its chairman holding a ministerial council seat. The KGB ended when its chief, Colonel-General Vladimir Kryuchkov, used the KGB's resources to help the August 1991 coup attempt to overthrow Soviet President Mikhail Gorbachev. On 23 August 1991 Colonel-General Kryuchkov was arrested, and General Vadim Bakatin was appointed KGB Chairmanand mandated to dissolve the KGB of the Soviet Union. On 6 November 1991, the KGB officially ceased to exist, although Russia's new national security organisation, the Russian "Federalnaya sluzhba bezopasnosti" (FSB), works in the same things that the Soviet KGB did.
Belarus is the only post-Soviet Union era country where the national security organization is still called "KGB". Belarus is where Felix Dzerzhinsky started a group called the Cheka, which was an organization in the Soviet Union before the MVD or the KGB was started.
Federal Security Service
The FSB (ФСБ) is an organisation in Russia that takes care of security of the country. It is the organisation that came after the KGB, relating to internal affairs inside the country. It is usually simply called the FSB in English-language sources.
Its main responsibilities are within the country. It does counter-intelligence, internal and border security, counter-terrorism, and surveillance. It also investigates some other types of serious crimes. Its headquarters are in Lubyanka Square, Moscow's centre, in the main building of the former KGB. The Director of the FSB since 2008 is army general Aleksandr Bortnikov.
Nicolaus Copernicus
Nicolaus Copernicus (19 February 1473 – 24 May 1543) was a Polish astronomer. People know Copernicus for his ideas about the sun and the earth. His main idea was that our world is "heliocentric" ("helios" = sun). His theory was that the sun is in the middle of the solar system, and the planets go around it. This was published in his book, "De revolutionibus orbium coelestium" (On the Revolutions of the Heavenly Spheres) in the year that he died.
Copernicus was born in 1473 in the city of Thorn (Toruń) in Royal Prussia, a mainly German-speaking state that was ruled by the Polish king since 1466. He was the son of the merchant Niklas Koppernigk and his wife Barbara Koppernigk (born Barbara Watzenrode). His native language was German. He was taught first in Cracow and then in Italy, where he graduated as a lawyer of the church. He also studied medicine to serve his fellow clerics. Copernicus spent most of his life working and researching in Frauenburg (Frombork), Warmia, where he died in 1543.
Copernicus was one of the great polymaths of his age. He was a priest, mathematician, astronomer, astrologer, jurist, physician, classical scholar, governor, administrator, diplomat, economist, and soldier. During all these jobs, he treated astronomy as a hobby. However, his doctrine of heliocentrism that the sun, rather than the earth, is at the center of the solar system, is one of the most important scientific hypotheses in history. It was the beginning of modern astronomy.
Projection (mathematics)
A projection in geometry is something like a shadow, that an object casts onto another object. When a three-dimensional sphere is projected onto a plane, its projection will either be a circle or an ellipse.
In higher mathematics, projections are changes of one thing into something else. They may also be applications of functions.
Drizzle
Drizzle is the name given to light rain. The drop size of drizzle is smaller than that of rain, about 0.5 mm (millimeters) in diameter.
Lightning
Lightning is a very powerful electrical discharge made during a thunderstorm. The electric current makes the air very hot. The suddenly heated air expands very quickly, which causes thunder. Sometimes lightning happens between clouds. Sometimes (in the rain) lighting goes from cloud to ground. If it goes from cloud to ground, it can strike a person. Around 2000 people are struck by lightning each year. About 50 to 100 lightning bolts strike the Earth every second. Lightning has hit the Empire State Building as many as 500 times a year.