Solar System Phenomena — Mercury in 2023

The path of Mercury against the background stars in 2023

The upper chart shows the path of Mercury across the background stars over the course of the year. Stars to magnitude +4.5 are shown with some fainter objects included to complete constellation patterns. The white circles represent the planet on the first day of the month and are scaled according to apparent magnitude. The faint paths before the first circle and after the last circle represent the planet's positions in December of last year and January of next. In general, the planet moves from right to left except when it's in retrograde and proceding in the opposite direction. As an inferior planet, Mercury never strays far from the Sun so it always begins and ends the year near the constellation of Sagittarius, located about one quarter of the way in from the left side of the chart.

The lower charts show how the appearance of Mercury changes over the year. Below each image is listed the date, the apparent magnitude, the apparent diameter of the disk (in arc-seconds), the geocentric distance (in au), the elongation from the Sun (in degrees) and the percentage of the disk which is illuminated. Like the Moon, Mercury exhibits a complete range of phases, from new to crescent to gibbous to full and back again. Because its synodic period is around four months, Mercury completes this phase cycle three times each year. Note how Mercury's magnitude varies widely, ranging (approximately) from −2.0 to +6.0 between conjunctions.

Mercury's first appearance in 2023 is in the west after sunset but it soon vanishes from the scene, to reappear in the morning sky. There are three more complete evening apparitions, with mid-March through May favouring northern temperate latitudes and July–September bringing the best viewing opportunities in tropical and southern regions. The first morning apparition (mid-January to mid-March) is slightly better than the following morning appearance (May–June) for equatorial regions, but the May–June apparition favours the southern hemisphere whilst the September to mid-October appearance is the best one for northern observers. The final morning apparition gets underway just as the year ends.

2perihelion: 0.308 au
7inferior conjunction
18stationary in right ascension: retrograde → direct
stationary in ecliptic longitude: retrograde → direct
206.9° north of the Moon
30greatest elongation west: 25.0°
5descending node
15aphelion: 0.467 au
183.6° north of the Moon
2planetary conjunction: 0.5° south of Saturn
15planetary conjunction: 0.4° north of Neptune
17superior conjunction
221.8° north of the Moon
27ascending node
28planetary conjunction: 1.3° south of Jupiter
31perihelion: 0.308 au
11greatest elongation east: 19.5°
211.9° north of the Moon
stationary in ecliptic longitude: direct → retrograde
stationary in right ascension: direct → retrograde
1inferior conjunction
4descending node
14stationary in right ascension: retrograde → direct
aphelion: 0.467 au
15stationary in ecliptic longitude: retrograde → direct
183.6° south of the Moon
29greatest elongation west: 24.9°
4planetary conjunction: 2.7° north of Uranus
164.3° south of the Moon
23ascending node
perihelion: 0.307 au
30maximum declination north: +24.42°
1superior conjunction
140.2° north of open cluster M44 (Praesepe)
193.5° south of the Moon
27planetary conjunction: 5.1° south of Venus
280.1° south of first-magnitude star α Leonis (Regulus)
31descending node
10greatest elongation east: 27.4°
aphelion: 0.467 au
186.9° south of the Moon
23stationary in right ascension: direct → retrograde
stationary in ecliptic longitude: direct → retrograde
6inferior conjunction
136.0° south of the Moon
15stationary in right ascension: retrograde → direct
stationary in ecliptic longitude: retrograde → direct
19ascending node
22greatest elongation west: 17.9°
23perihelion: 0.307 au
14lunar occultation: 0.7° north of the Moon (daytime event)
20superior conjunction
descending node
29planetary conjunction: 0.3° north of Mars
11aphelion: 0.467 au
141.6° north of the Moon
162.5° north of first-magnitude star α Scorpii (Antares)
30maximum declination south: −25.86°
4greatest elongation east: 21.3°
144.4° north of the Moon
15ascending node
20perihelion: 0.307 au
22inferior conjunction
28planetary conjunction: 3.6° south of Mars


The dates, times and circumstances of all planetary and lunar phenomena were calculated from the JPL DE406 solar system ephemeris using the same rigorous methods that are employed in the compilation of publications such as The Astronomical Almanac.