The sky on December 21, 1984 — as it really was
That day the Sun stood in Sagittarius — sign and constellation agree here.
Bodies on the ecliptic (noon UTC)
- ☉︎ Sun — 269.8° · sign Sagittarius · constellation Sagittarius
- ☽︎ Moon — 257.1° · sign Sagittarius · constellation Ophiuchus
- ☿︎ Mercury — 255.4° · sign Sagittarius · constellation Ophiuchus
- ♀︎ Venus — 314.4° · sign Aquarius · constellation Capricornus
- ♂︎ Mars — 327.1° · sign Aquarius · constellation Aquarius
- ♃︎ Jupiter — 289.0° · sign Capricorn · constellation Sagittarius
- ♄︎ Saturn — 233.7° · sign Scorpio · constellation Libra
- ☽︎ Moon 1% illuminated
astronomy-engine ephemerides (VSOP87/ELP), IAU 1930 constellation boundaries. Positions accurate to a fraction of a degree.
The day’s dossier, from real data
Checkable facts with a tag and a source; the classical reading is in the chart.
- The Moon that day [EXACT]
new moon, 1% lit; the Moon was 372,848 km away.
astronomy-engine - How far Earth has travelled since [EXACT]
41.8 orbits of the Sun — 39,269 million km, that is 51,079 return trips to the Moon; 15,262 rotations of Earth; with the Sun — 303.3 billion km around the Galactic centre, 11.7 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 247 million km away; today it is 245 million km (closer by 1×).
astronomy-engine; checked against JPL Horizons for 2026-09-14 - Solar cycle [ESTIMATE]
That day fell in solar cycle 21, on the decline (84% through the cycle).
SILSO smoothed minima - When the sky repeats [EXACT]
Mars returns to that day’s point of its orbit on March 26, 2028; Jupiter — in 2031; 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 2,088″ since that day; the real constellations now sit 23.7° away from the astrologers’ “signs”.
precession 50.29″/yr
Other dates
Computed from the date only; nothing about you is stored.