2021 at a Glance
10 retrograde periods overlap 2021. By planet: Mercury three times, Venus once, Jupiter once, Saturn once, Uranus twice, Neptune once and Pluto once. Uranus is already retrograde on January 1. Mars has no retrograde period in 2021.
There are 12 full moons and 12 new moons in 2021 — the first new moon is on January 13 in Capricorn, the first full moon on January 28 in Leo. Planets from the Sun to Pluto change sign 48 times in total, including 3 sign changes by the slow outer planets (Jupiter into Pisces on May 14, Jupiter into Aquarius on July 29 and Jupiter into Pisces on December 29).
Mercury Retrograde 2021
Retrograde motion is apparent, not real. Seen from Earth, a planet normally drifts eastward against the background stars; for a stretch of weeks or months it seems to stop (a “station”), slide back westward, and stop again before moving forward. The planet's orbit never reverses — the effect comes from Earth and the planet circling the Sun at different speeds. Mercury and Venus appear to back up as they overtake Earth while passing between Earth and the Sun; the outer planets do so when Earth overtakes them on the inside track.
In astrological tradition, Mercury retrograde is associated with mix-ups in communication, contracts and travel, so many people double-check details and back up their work on these dates.
All Planetary Retrogrades 2021
How often a planet turns retrograde depends on how its orbit compares with Earth's. Mercury does so three or four times a year for about three weeks each; Venus roughly every 19 months for about six weeks; Mars about every 26 months for two to two and a half months. Jupiter, Saturn, Uranus, Neptune and Pluto are retrograde once a year for roughly four to five and a half months, so a period that spans New Year appears in both years' calendars.
| Planet | Retrograde | Direct again | Sign |
|---|---|---|---|
| Uranus | January 1already retrograde | January 14 | Taurus |
| Pluto | April 28 | October 6 | Capricorn |
| Saturn | May 24 | October 11 | Aquarius |
| Jupiter | June 21 | October 18 | Pisces → Aquarius |
| Neptune | June 26 | December 1 | Pisces |
| Uranus | August 21 | December 31 (into 2022) | Taurus |
| Venus | December 20 | December 31 (into 2022) | Capricorn |
Full and New Moons 2021
A new moon is the moment the Moon and the Sun share the same ecliptic longitude: the Moon's sunlit side faces away from Earth, so it is not visible. A full moon is the opposite alignment — the Moon sits 180° from the Sun, in the sign opposite the Sun's, with its whole Earth-facing side lit. One cycle from new moon to new moon (the synodic month) takes about 29.5 days, so most years have 12 full moons and some have 13. Solar eclipses can only happen at a new moon and lunar eclipses only at a full moon.
Full Moons 2021
Astrologers read full moons as culminations.
Planet Sign Changes 2021
An ingress is the moment a planet crosses from one zodiac sign into the next. The signs used here are the tropical zodiac — twelve 30° segments of the ecliptic counted from the March equinox point — so an ingress is simply the planet's geocentric longitude crossing a multiple of 30°. The Sun enters a new sign about once a month; Jupiter spends about a year in each sign, Saturn about two and a half years, and Pluto anywhere from about 12 to over 30 years because of its eccentric orbit. A planet near a boundary can cross back and forth while it is retrograde, which is why the same ingress can appear more than once in a year.
In astrology, a planet's themes are read through the sign it occupies, so an ingress marks a change of emphasis.
FAQ
When is Mercury retrograde in 2021?
Mercury is retrograde 3 times in 2021: January 31 – February 21 (in Aquarius); May 30 – June 22 (in Gemini); September 28 – October 18 (in Libra).
How many full moons are there in 2021?
There are 12 full moons in 2021. The first is on January 28 in Leo.
How are these dates calculated?
All dates are computed from geocentric tropical ephemeris (real planetary positions), not copied from other sites. Times are in UTC; dates near midnight may shift by one day in your timezone.