THE 2026-2027 APHELIC APPARITION OF MARS
By: Jeffrey D. Beish (25-OCT-2020)
   

INTRODUCTION

Mars appears more Earth-like to us than most of the other planets because we can observe its surface, atmospheric clouds and hazes, and its brilliant white polar caps.  The latter are composed of frozen CO₂ and underlying water ice, and wax and wane during the Martian year. These aspects, along with the changing seasons and the possibility of life, have made Mars one of the most studied planets in our solar system.

The Red Planet Mars offers both casual and serious observers many challenges and delights, as well as providing astronomers a laboratory to study another planet’s atmosphere and surface. Some Martian features even appear to shift position around the surface over extended periods of time. There are several cooperating international Mars observing programs under way to assist both professional and amateur astronomers. These include the International Mars Patrol (I.M.P.) coordinated by the Mars Section of the Association of Lunar and Planetary Observers (A.L.P.O) and the Terrestrial Planets Section of the British Astronomical Association (B.A.A.). Information for observing Mars during a typical apparition is presented in a separate report titled, General Information for Apparitions of Mars. Also, you can find gobs of information at this site.

With the advent of modern CCD camera technology the amateur can produce useful images of Mars when it is as small as 3.5 arcsec . Early in an apparition, Mars rises in the east or morning sky and sets with the rotation of the Earth in the western or evening sky.  During the past few apparitions (2018-2025), observers began to take CCD images when Mars was only 30 degrees away from the Sun.  Since Mars was only a visual magnitude of ~1.8 then the planet would have been difficult to locate bright twilight hours.

In the pre-apparition reports the observer will find the motion of Mars in our sky, the characteristics for that particular apparition, information pertaining to the polar cap(s) and any special events that may be seen during that particular apparition.  As usual a calendar of events will be included with each report that contains cardinal dates for seasonal activity and orbital information of Mars.

MOTION OF MARS IN OUR SKY

As a general rule, an "apparition" begins when a planet emerges from the glare of the Sun shortly after conjunction. Mars will be in conjunction with the Sun on January 09, 2026 at 09:59UT (203.8° Ls); however, it will not be safe to observe Mars until after March 03, 2026 when it is at least 12 degrees away from the glare of the Sun. By November 20, 2026, a 0.6 visual magnitude Mars is seen rising early in the morning sky in the constellation Leo, it will be at western quadrature and the phase or terminator will be 38°.

The apparent declination of Mars begins at -23° in early January 2026 and continues to climb northward until opposition. This is good news for those observing in the Northern Hemispheres because Mars will be seen high in their sky. Mars will be below the celestial equator until April 13, 2026.  

NOTE: The Solar Elongation for Mars is the angle between the lines of sight from Earth to the Sun and from Earth to Mars.  When these lines of sight form a right triangle then Mars is at quadrature (eastern or western). For detailed definitions and graphics for the motion of Mars in our sky see these excellent web sites:  Planetary Aspects and Elongations and Configurations.

Figure 1. A heliographic chart of the orbits of Mars and the Earth showing the relative positions of both planets.  Quadrature is when Mars is directly east or west of Earth as shown.

The 2026-2027 Mars apparition begins retrogression, or retrograde motion against the background stars just over a year after conjunction from January 10, 2027 (47.5° Ls) through April 01, 2027 (83° Ls). Each night for this brief period before, during and after opposition the Red Planet will appear to move backwards toward the western sky from the constellation in Leo. Since the Martian year is about 687 Earth days long -- nearly twice as long as ours, the Martian seasons are similarly extended. While the Earth’s seasons are nearly equal in duration, the Martian seasons can vary by as much as 52 days from each other due to that planet’s greater orbital eccentricity (see Figure 2).

Figure 2. A heliographic chart of the orbits of Mars and the Earth showing the relative seasons of both planets in the planetocentric longitude system Ls. Graphic Ephemeris for the 2027 Aphelic Apparition of Mars. Original graph prepared by C.F. Capen and modified by J.D. Beish.

2027 APPARITION CHARACTERISTICS

Another general rule for predicting oppositions of Mars is from the following: the planet has an approximate 15.8-year periodic opposition cycle, which consists of three or four Aphelic oppositions and three consecutive Perihelic oppositions. Perihelic oppositions are also called "favorable" because the Earth and Mars come closest to each other on those occasions. We sometimes refer to this as the seven Martian synodic periods. This cycle is repeated every 79 years (± 4 to 5 days) and, if one were to live long enough, one would see this cycle nearly replicated in approximately 284 years. The 2027 Mars apparition is considered Aphelic because the orbital longitude at opposition will be only 4.5° from the aphelion longitude 70° Ls.

NOTE: Ls is the planetocentric longitude of the Sun along the ecliptic of Mars’ sky. 0° Ls is defined as that point where the Sun crosses the Martian celestial equator from south to north, that is the planet’s northern hemisphere vernal equinox. The other Ls values that define the beginnings of Martian northern hemisphere seasons are: summer, 90° Ls; autumn, 180° Ls; and winter, 270° Ls. For Mars’ southern hemisphere these values represent the opposite seasons. Distance (A.U.) - Distance from Earth to Mars in astronomical units, where one (1) A.U. equals 92,955,807.267 miles or 149,597,870.691 km.

Opposition occurs 14.3 months after conjunction, when Mars is on the opposite side of the Earth from the Sun. At that time, the two planets will lie nearly in a straight line with respect to the Sun, or five weeks after that retrogression begins. Opposition will occur at 1545 UT on February 19, 2027 (65.4° Ls), with an apparent planetary disk diameter of 13.8 arcsec. Mars will remain visible for a year after opposition and then become lost in the glare of the Sun again (May 13, 2028) as it approaches the next conjunction March 21, 2028 at 0116 UT (275.6° Ls). The cycle is complete in 780 Earth days.

Closest approach ooccurs at 0014 UT on February 20 (65.5° Ls) with an apparent planetary disk diameter of 13.8’’ at a distance of 0.6779190 astronomical units (AU) or 63,016,511 miles (101,415,244 km). During closest approach in 2027 the apparent diameter of Mars will be 0.8 arcsec smaller than it was at the same period in 2025 and it will be 9.4 degrees lower in the sky - favorably placed for observing the Red Planet. [NOTE: one (1) A.U. equals 92,955,807.267 miles or 149,597,870.691 km]. It should also be noted that closest approach between Earth and Mars is not necessarily coincident with the time of opposition but varies by as much as two weeks.

Figure 3. A simulated view of the appearance of Mars during opposition at 1545 UT on February 19, 2027 (65.4° Ls, CM 34°)  

The observable disk diameter of Mars will be greater than 6 arcsec from October 14, 2026 [19.2° δ] (6.7° Ls) and will not fall below this value until July 01, 2027 [3.7° d] (124.1° Ls), lasting nearly 8.7 months or 117 degrees Ls. This apparition will follow a similar profile to the 2012 apparition of Mars. Imaging by CCD devices may begin with a disk diameter of 4 arcsec or more, commencing on or about February 09, 2026.

The Sub-Earth (De) and Sub-Solar (Ds) points are graphically represented in Figures 4 and 5. The 2026-2027 Ephemeris of Mars is tabulated on Internet in this web site. A glossary of Terms appears at the end of this table.

Figure 4. As it approaches Earth, it will swell from a small apparent disk of 6" in October14, 2026 to a maximum diameter on July 01, 2027, and then shrink as it moves away. Closest approach occurs on February 20 (65.5° Ls). Opposition on February 19, 2027 (65.4° Ls). From October 2026 through June 29 are the prime observing months. Images shows at 0h UT.

Figure 5. Graphic Ephemeris of Mars during the 2026-2027 apparition from October 14, 2026 through July 01, 2027. Opposition (65.5° Ls) and 6 arcsec apparent diameter range arc indicated. Plot illustrates the Declination (solid line), the latitude of the Sub-Earth point (De) or the apparent tilt (dashed line) in areocentric degrees, and the latitude of the Sub-Solar point (dotted line) in areocentric degrees. The areocentric longitude (Ls) of the Sun, shown along the bottom edge of the graph defines the Martian seasonal date. The value of Ls is 0° at the vernal equinox of the northern hemisphere, 70° when Mars is at aphelion, and 90° at the summer solstice of the northern hemisphere 250° when Mars is at perihelion, and 180° is northern autumn.

Figure 6. Graphic Ephemeris of Mars from October 14, 2026 through July 01, 2027. Opposition (65.5° Ls) and 6 arcsec apparent diameter range arc indicated. Plot illustrates the apparent diameter of Mars in seconds of arc. The areocentric longitude (Ls) of the Sun, shown along the bottom edge of the graph defines the Martian seasonal date.

THE NORTH AND SOUTH POLAR REGIONS

Astronomers will have an excellent view of the prominent north polar cap during most of the next apparition because it will be tilted earthward during the entire apparition. The terminator shadow will cover part of polar cap until late-November 2026 when the cap will become completely sunlit. For more detailed information on the For more detailed information on the north polar cap click to this web site.

DUST STORMS

Observations of Mars indicate that dust storms occur around the time of southern summer solstice, soon after Mars reaches perihelion. However, accurate predictions are nearly impossible to make because of the complexities and unknown variables. When a great dust storm reaches maturity, Mars’ disk appears bright orange and Mars’ surface features are obscured. For more detailed information on Martian dust storms on this web site Martian dust storms

While Mars will be too close to the Sun the Martian dusty season should begin about the third week in January (210° Ls) throughout the first week of August 2026 (330° Ls). The highest probability of dust storms occurring will be on or about March 05, 2026 (241° Ls) and a sensitive area for the development of dust storms is in northwest Hellas. Also, dust clouds and storms have been observed during northern summer (105° Ls) and be on the watch on or about May 20, 2027.

Another sensitive period following the "procurer" storm season will come in the middle of July 2026 (315° Ls) when observers should be alert for dust clouds in the northeast Hellas Basin, the Serpentis-Noachis region, and the Solis Lacus region.