Sky on December 21, 2009: where the Sun, Moon and planets really were

The real sky on December 21, 2009: Sun in Sagittarius (horoscope says "Sagittarius"), Moon 21% lit, planet positions from ephemerides.

The sky on December 21, 2009 — as it really was

That day the Sun stood in Sagittarius — sign and constellation agree here.

astronomy-engine ephemerides (VSOP87/ELP), IAU 1930 constellation boundaries. Positions accurate to a fraction of a degree.

Checkable facts with a tag and a source; the classical reading is in the chart.

The Moon that day [EXACT]
waxing crescent, 21% lit; the Moon was 405,319 km away.
astronomy-engine
How far Earth has travelled since [EXACT]
16.8 orbits of the Sun — 15,775 million km, that is 20,519 return trips to the Moon; 6,131 rotations of Earth; with the Sun — 121.8 billion km around the Galactic centre, 4.7 light-days.
29.78 km/s along the orbit; 230 km/s around the Galactic centre
Mars then and now [EXACT]
On that day Mars was 120 million km away; today it is 246 million km (farther by 2.1×).
astronomy-engine; checked against JPL Horizons for 2026-09-14
Solar cycle [ESTIMATE]
That day fell in solar cycle 24, right at the minimum (10% through the cycle).
SILSO smoothed minima
When the sky repeats [EXACT]
Mars returns to that day’s point of its orbit on November 25, 2026; Jupiter — in 2033; a full moon exactly on this date — December 20, 2029
sidereal periods: Mars 686.98 d, Jupiter 11.862 yr
How far the sky has drifted since [EXACT]
The vernal point has shifted 828″ since that day; the real constellations now sit 24° away from the astrologers’ “signs”.
precession 50.29″/yr
Picture of the day [EXACT]
NASA Astronomy Picture of the Day for this date: apod.nasa.gov/apod/ap091221.html
NASA APOD

Computed from the date only; nothing about you is stored.