Astronomy is the foundation upon which astrology can operate. Actually, astrology and astronomy were treated together, under the Latin name of astrologia, being separated only by the Western 17th century philosophy. One thing is sure: a good astrologer needs to study astronomy. Here you can find the astronomy calendar for December 2018.


Friday, December 7th: New Moon

The New Moon is when the Sun and Moon are aligned, with the Sun and Earth on opposite sides of the Moon. The new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the unaided eye, except when silhouetted during a solar eclipse. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


Thursday, December 13th, Friday, December 14th: Geminids Meteor Shower

The Geminids are considered to be one of the most spectacular meteor showers of the year, with the possibility of sighting around 120 meteors per hour at its peak. The Geminids are a meteor shower caused by the object 3200 Phaethon, which is thought to be an asteroid with a “rock comet” orbit. This would make the Geminids, together with the Quadrantids, the only major meteor showers not originating from a comet. Meteors will radiate from the constellation Gemini, but can appear anywhere in the sky.

Saturday, December 15th: Mercury at Greatest Western Elongation

In astronomy, a planet’s elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The planet Mercury reaches greatest western elongation of 21.3 degrees from the Sun. December 15th is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky.

Friday, December 21st: December Solstice

This is the first day of winter (winter solstice) in the Northern Hemisphere and the first day of summer (summer solstice) in the Southern Hemisphere. The South Pole of the earth will be tilted toward the Sun, which will have reached its southernmost position in the sky and will be directly over the Tropic of Capricorn at 23.44 degrees south latitude.

Friday, December 21st, Saturday, December 22nd: Ursids Meteor Shower

The shower is named the Ursids because the meteors seem to radiate from the direction of the constellation Ursa Minor in the sky. The Ursids are associated with the 8P/Tuttle comet. Meteors will radiate from the constellation Ursa Minor, but can appear anywhere in the sky.

Saturday, December 22nd: Full Moon.

The full moon is the lunar phase when the Moon appears fully illuminated from Earth’s perspective. This occurs when Earth is located directly between the Sun and the Moon (more exactly, when the ecliptic longitudes of the Sun and Moon differ by 180°). This means that the lunar hemisphere facing Earth – the near side – is completely sunlit and appears as a circular disk, while the far side is dark. This full moon was known by early Native American tribes as the Full Cold Moon, because this is the time of year when the cold winter air settles in and the nights become long and dark. Other names given to this moon were the Full Long Nights Moon and the Moon before Yule.