Pioneer 10 was launched 2 March 1972 from Cape Canaveral on a three stage Atlas Centaur rocket. It visited Jupiter for a few days in December 1973 and was flung out of the solar system by the massive planet. After more than 30 years the venerable spacecraft sent its last signal to Earth on 22 January 2003. At last contact Pioneer 10 was 82 astronomical units away from the sun (more than twice the average distance from the sun to Pluto). The last detectable radio signal (which was too weak to be decipherable) took 11 hours and 20 minutes to reach the earth. Pioneer 10 is currently 105 astronomical units from the sun and is traveling at 12 km/s.
English explorer Robert F. Scott and his expedition arrive at the South Pole on 18 January 1912, only to discover that Roald Amundsen had gotten there first. Everyone in the expedition died on the return journey. See my post on Amundsen’s arrival for more info.
December 25th 1642 Julian calendar: Sir Isaac Newton is born. Jesus on the other hand was actually born in the summer. His birthday was moved to coincide with the traditional pagan holiday that celebrated the winter solstice with lit fires and slaughtered goats.
Frank Borman, James Lovell, and William Anders became the first humans to orbit the moon. On 24 December 1968, as they came from behind the Moon on their fourth orbit they saw the earth rise above the horizon. Anders snapped the now famous photo.
The Wright Brothers (bicycle makers from Dayton, Ohio) made the first four sustained and controlled heavier-than-air powered flights on 17 December 1903. Orville Wright piloted the first flight of 120 feet (36.5 m) in 12 seconds. Wilbur Wright took the controls for the second flight when this famous photograph was taken.
The termination shock is the locus of points in space where the solar wind basically stops blowing outward from the sun and begins to drift with the background gases of interstellar space. It is one way to mark the edge of the solar system.
The two Voyager space probes were launched in 1977 to study the giant outer planets — Jupiter, Saturn, Uranus, and Neptune. They are on escape trajectories and will never return.
Distances within the solar system are frequently measured in astronomical units. One AU is equal to the average distance from the sun to the earth, about 150 million kilometers (93 million miles). Both Voyagers are currently more than 100 AU from the sun. For comparison, Jupiter is about 5 AU from the sun and Neptune is about 30 AU from the sun. Everybody’s favorite non-planet Pluto has an orbit that varies in size from about 30 AU to about 50 AU.
Voyager 1 crossed the termination shock of the supersonic flow of the solar wind on 16 December 2004 at a distance of 94.01 astronomical units from the Sun, becoming the first spacecraft to begin exploring the heliosheath, the outermost layer of the heliosphere.
The Yutu (玉兔) lunar rover successfully separated from the Chang’e-3 (嫦娥三号) lander early in the Chinese morning at 4:40 AM Sunday Bejing Time on 15 December 2013 (3:40 PM Saturday, 14 December 2013, Eastern Time). These 3 animated gifs show the process as broadcast on China Central Television (from a blogpost by Emily Lakdawalla of The Planetary Society).