December 26, 2011 - These Laws Can't Be Broken

These Laws Can’t Be Broken Johannes Kepler, born 440 years ago this week, was a German mathematician who used decades of precise measurements of planetary positions made by Danish astronomer Tycho Brahe to formulate three laws that describe planetary motion. These humble laws, which in part state that planets move in elliptical orbits, speeding up when closer to the Sun and slowing down when farther away, form the basis for our current ability to send spacecraft to explore the planets. Jupiter (above) obeys these laws as it orbits the Sun; the Hubble Space Telescope (which took the picture) follows them as it orbits the Earth; and even the rogue asteroid that slammed into Jupiter in 2009 leaving a “black eye” in the southern hemisphere was itself simply obeying these immutable laws.

Image credit: NASA / ESA / H. Hammel (Space Science Institute) / Jupiter Impact Team

Weekly Calendar

December 26, 2011 - January 1, 2012

Holidays - Sky Events - Space History

Moon phase Monday 26

Boxing Day (Canada, U.K., Australia)
First Day of Kwanzaa

Jupiter appears stationary

Moon phase Tuesday 27

Venus 6° south of Moon

1571: Johannes Kepler born
1984: Meteorite ALH 84001 discovered

Moon phase Wednesday 28

Neptune 6° south of Moon

1882: Arthur Eddington born

Moon phase Thursday 29

Pluto in conjunction with Sun

1980: STS-1 leaves Vehicle Assembly Building and rolls out to launch pad

Moon phase Friday 30

1957: Wernher von Braun proposes the Saturn-class launch vehicle

Moon phase Saturday 31

New Year's Eve

Uranus 6° south of Moon

1864: Robert Aitken born
2004: Cassini makes first flyby of Iapetus

Moon phase Sunday 1

New Year's Day

First Quarter Moon 1:15 AM ET

1801: Giuseppe Piazzi discovers asteroid Ceres

Suggestions for new history dates or better links? Corrections for errors on this page? Please e-mail me.