Yuri Gagarin orbited the earth 46 years ago today, which was dubbed as Cosmonautics Day. In addition, this year marks the 50th anniversary of the first artificial satellite put into geocentric orbit. 

On 12 April, 1961, Gagarin became the first human to orbit the earth. His spacecraft, Vostok 1, circled the planet at a speed of 27 400 kph. At the highest point, Gagarin was about 327km above ground.
In 1957, 50 years ago, Sputnik 1 was launched from the Baikonur Cosmodrome, marking a historic technological leap as the first man-made object to enter earth orbit – ushering in the Space Age and triggering an international space race.
Equipped with two radio transmitters, the satellite emitted radio signals at 20MHz and 40MHz and its intermittent "beeps" were picked up by scientists and radio operators around the world.
From a scientific angle, the satellite helped identify the density of high atmospheric layers and provided data on radio-signal distribution in the ionosphere.
Sputnik 1 flew at 29 000 kmph, orbiting the globe every 96 minutes and covered about 60-million kilometers before burning out on re-entering earth’s atmosphere.