December 27

1571 – Astronomer Johannes Kepler is born. He formulated three major laws of planetary motion, which in turn enabled Isaac Newton to devise the law of gravitation.
1831 – Charles Darwin embarks on his journey of scientific discovery aboard the HMS Beagle, during which he will begin to formulate his theory of biological evolution through natural selection.
2004 – Radiation from an explosion on the magnetar "SGR 1806-20" reaches Earth. It is the brightest extrasolar event known to have been witnessed on the planet.