This cycle begins on December 18th with the Sun and new Moon in Sagittarius; and comes to fruition on January 2nd, 2018 with the full Moon in Cancer and the Sun in Capricorn.
It seems my numbering system for cycles has failed with this one numbered 13. Astrology's yearly cycles are 12 in number and are based on the Sun moving "through" the constellations in relation to the Earth (tropical astrology); but the Moon's synodic cycle "takes 29–30 days. The moon completes its orbit around the earth in 27.3 days (the sidereal month), but due to the Earth's motion around the sun it has not finished a full (synodic) cycle until it reaches the point in its orbit where the sun is in the same position ." (Wikipedia)
So there can be 12-and-a-half to nearly 13 cycles in a year. There are many ways to look at the Moon's long and short cycles, so take a look at the Wikipedia article on Lunar Month for more information.
Something not dealt with in this blog previously are the synodic cycles of all the planets. Often they are used in natal astrology when relating a planet to its starting position in the zodiac; but they can also be discussed in terms of one planet to another, such as Venus to Mars. For a good discussion of synodic cycles, check out Synodic Astrology: Synodic Cycles and Planetary Retrogrades at the Lunar Planner.
On the 21st of December the Sun crosses 0° Capricorn, commonly called the Winter Solstice, also known as the Winter Ingress by astrologers. This signals the promise of longer days for those of us above the Equator. Astrologers are divided on whether this marker or the one at 0° Aries (Spring Equinox) signifies the beginning of a new astrological year. In her blog, Diary of a Mundane Astrologer, Raye Robertson presents some interesting points on the Winter Ingress. A chart for the Winter Ingress is available.
Two U.S natal charts are again being considered--one with Scorpio rising and one with Sagittarius rising (new Moon and full Moon are linked here). In the natal chart with Scorpio rising the Sun is positioned in the 9th house, ruled by Jupiter; Sagittarius rising places the Sun in the 7th house, ruled by Venus. Both placements include the Moon as ruler because the Sun is in Cancer. In the Sagittarian chart the Moon's placement is in the 3rd house, conjunct the cusp; in the chart with Scorpio rising the Moon is in the 4th house, her home.
Currently, Uranus, Ceres, and Mercury are retrograde. Mercury will turn direct in Sagittarius on December 23rd and Uranus will turn direct in Aries on January 3rd. Ceres will remain retrograde until mid-March.
At the new Moon there is a large stellium in Scorpio, containing Mercury, Venus, Moon, Sun, and Saturn. At the full there is another stellium, this time in Capricorn; it contains Saturn, Venus, Sun, and Pluto. Common to both stelliums are the Sun, Saturn, and Venus.