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 (2025-2029), observers began to take CCD images when Mars was only 32 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 May 25, 2030 (338.6° Ls); however, it will not be safe to observe Mars until after July 09, 2030 when it is at least 12 degrees away from the glare of the Sun.
The apparent declination of Mars begins at -7.1° in early January 2031 in the constellation Virgo and descends south of the celestial equator throughout the apparition. By the end of January, February, March, April and the third week of May Mars will be in Libra; however, will slip into Scorpius until August 20 then into Ophiuchus. This is not good news for those observing in the Northern Hemispheres because Mars will be seen fairly low in their sky during the entire apparition. Good news for southern hemisphere observers however. The declination of Mars will continue to descend south of the celestial equator for the remainder of he apparition.
By January 24, a '0.8' visual magnitude Mars will be seen rising early in the morning sky in the constellation Virgo and it will be at western quadrature with the phase defect or terminator at 36.5°. 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 2030-2031 apparition of Mars begins retrogression, or retrograde motion against the background stars ten months after conjunction on March 29, 2031 (120.9° Ls) and continues through June 13, 2031 (158.5° Ls). Each night for this brief period of time; before, during and after opposition the Red Planet will appear to move backwards toward the western sky in the Virgo.
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 2014 Aphelic Apparition of Mars. Original graph prepared by Roger Venable (ALPO Mars Section).
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 2031 Mars apparition is considered Transitional (between Aphelic and Perihelic) because the orbital longitude at opposition will be 68.4° from the aphelion longitude of 70° Ls and 111.6° Ls from perihelion (250° 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 11 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 retrogression begins. Opposition will occur at 1026 UT on May 04, 2031 (138.4° Ls) with an apparent planetary disk diameter of 16.7 arcsec. Mars will remain visible for more than twelve months after opposition and then become lost in the glare of the Sun around May 31, 2032 as it approaches the next conjunction (July 11, 2032). The cycle is complete in 780 Earth days.
Closest approach occurs at 0350 UT on May 12, 2031 (142.1° Ls) with an apparent planetary disk diameter of 16.9 at a distance of 0.5533578 astronomical units (AU) or 51,437,823 miles (82,781,152 km). During closest approach in 2031 the apparent diameter of Mars will be 2.4 arcsec larger than it was at the same period in 2029; however, it will be 17.1 degrees lower in the sky - not quite as good for observing the Red Planet for observers in the northern hemisphere. 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 1026 UT on May 04, 2031 (138.4° Ls, CM 298.3°)
The observable disk diameter of Mars will be greater than 6 arcsec from January 01, 2031 [-7.1°δ] (81.7° Ls) and will not fall below this value until November 27, 2031 (284.8° Ls), lasting 11 months or 203 degrees Ls. Imaging by CCD devices may begin with a disk diameter of 3.7 arcsec or more, commencing on or about July 09, 2030.
The Sub-Earth (De) and Sub-Solar (Ds) points are graphically represented in Figures 4 and 5. The 2030 and 2031 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 January 01, 2031 to a maximum diameter on November 27, 2031, and then shrink as it moves away. Images shown at 0h UT.
Figure 5. Graphic Ephemeris of Mars during the 2030-2031 apparition from January 01, 2031 through November 27, 2031. Opposition (138.4° 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 251° when Mars is at perihelion, and 180° is northern autumn.
Figure 6. Graphic Ephemeris of Mars from January January 01, 2031 through November 27, 2031. Opposition (138.4° 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 POLAR REGION
Astronomers will have a view of the north polar region during the this apparition. From the first week in January 2031 the Martian North Polar Region (NPR) will be tilted toward the Earth and will remain so until August 10, 2031 when it reaches 15° De and should be free of its hood. For more detailed information on the north polar cap click to this web site.
Observations of Mars indicate
that dust storms occur around the time of northern summer
solstice (90° - 105° Ls). 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.
CALENDAR OF EVENTS -- MARS, 2030-2031
|2030 May 25||Ls 338.6°||Conjunction. Mars is behind the Sun ~2.517 AU.|
|2030 Jul 05||Ls
|Equinox - Northern Spring/Southern Autumn. North Polar Hood (NPH) begins to break up. North Polar Cap (NPC) should be exposed at approximately 65° Areographic latitude. ("Areo-" is a prefix often employed when referring to Mars or "Ares.")|
|2030 Dec 05||Ls
A. Dia 5.1’’
|Mars at Aphelion. Is NPC fairly static or entering rapid retreat phase. Watch for "Aphelic Chill" in NPR (usually between 60° and 70° Ls). NPC Rima Tenuis may appear. Antarctic hazes, hood. South polar regions becoming difficult to observe. Any signs NPC width ~31° ±3°|
|2031 Jan 01||Ls
A. Dia 6’’
|Apparition begins for observers using 4-inch to 8-inch apertures telescopes and up. Begin low-resolution CCD imaging. Views of surface details not well defined. NPC in rapid retreat? Are limb arcs increasing in frequency, intensity. Antarctic hazes/hood. Cloud activity increases. "Aphelic Chill" in NPR should be ended.|
|2031 Jan 20||Ls
A. Dia 6.8’’
|Solstice - Northern Summer/Southern Winter. Orographic clouds over the Tharsis volcanoes – W-Cloud? Local seasonal clouds should wrap around Syrtis Major and be prominent in Lybia. Hellas white cloud and Ice-fog activity? Discrete clouds? NPC remnant? Lemuria (210° W, 82° N) detached from NPC? Any other detachments (projections at 135° W and 290° W) near NPC remnant, NPC Width ~18° ±4°.|
|2031 Jan 24||Ls
|Mars at quadrature. Orographic clouds over the Tharsis volcanoes - W-Cloud? Local seasonal clouds should wrap around Syrtis Major and be prominent in Lybia. Hellas white cloud and Ice-fog activity? Discrete clouds? NPC remnant? Lemuria (210° W, 82° N) detached from NPC? Any other detachments (projections at 135° W and 290° W) near NPC remnant? NPC width ~15° ±3°|
|2031 Feb 09||Ls
|Novus Mons reduced to a few bright patches and soon disappears. Windy season on Mars begins, dust clouds present? Watch for initial dust clouds in south. White patches in bright areas? Hellas bright spots? Numerous bright patches. Watch for "Aphelic Chill" in NPR - (usually between 60° and 70° Ls) and possible halt in thawing of NPC. Views of surface details well defined. Rima Tenuis may appear (140° and 320° Areographic meridians). Cloud activity in north increasing? (NPC Width ~17° ±3°).|
|2031 Mar 05||Ls
|NPC still retreating? Are limb arcs increasing in frequency, intensity? Antarctic hazes, hood? Cloud activity high? Tempe-Arcadia-Tharsis-Amazonis regions bright in a pattern appearing as the "domino effect." Discrete clouds? NPC width ~16° ±3°|
|2031 Mar 22||Ls
A. Dia 12’’
|Is Mare Acidalium broad and dark? Bright spots in Tempe-Arcadia-Tharsis-Amazoins? "Domino effect" appears around 120° - 125° Ls. Topographic clouds increase. (NPC Width ~15° ±3°).|
|2031 Mar 29||Ls
A. Dia 12.8’’
|Retrogression Begins. Mars begins retrogression, or retrograde motion against the background stars 10 months after conjunction, when it appears to move backwards toward the west for a brief period before, during and after opposition. Is Mare Acidalium broad and dark? Bright spots in Tempe-Arcadia-Tharsis-Amazoins? "Domino effect" appears around 120° - 125° Ls. Topographic clouds increase. (NPC Width ~15° ±3°).|
|2031 May 04||Ls
|Mars at Opposition. If both polar caps are visible look for haze canopy? Clouds and frosts prominent in north. Clouds area in south. Syrtis Major broad.|
|2031 May 12||Ls
|Mars at Closest Approach. If both polar caps are visible look for haze canopy? Clouds and frosts prominent in north. Clouds area in south. Syrtis Major broad.|
|2031 Jun 13||Ls
|Retrogression Ends. Mars begins westward motion against the background stars. . Are both polar hoods visible? SPH present and edge of NPH visible. Hellas frost covered? Are W-clouds present? Is Morpheos Lacus (228°W, 37°N) prominent? Are topographic clouds prominent in Libya, Aeria, Moab, Edom, and Candor?|
|2031 Jul 11||Ls
|Late southern winter, SPH present and edge of NPH visible. Hellas frost covered? Are W-clouds present?|
|2031 Jul 22||Ls
|Equinox - Northern Autumn/Southern Spring. South Polar Cap (SPC) maximum width. Is the North Polar Hood present? Does SPH or frost cover Hellas? Hellas should begin to clear and darken. Are W-clouds present? South cap emerges from darkness of Winter. SPH thinning and forms "Life Saver Effect"?|
|2031 Aug 07||Ls
|SPC should be free of its hood, large and bright. Possible W-clouds in Tharsis-Amazonis. Syrtis Major shrinks or fading on eastern border. NPH bright. White areas brighter? White areas brighter? Within Hellas the features Zea Locus and Alpheus darkening? Mare Hadriacum (265°W, 40°S) and Yaonis Regio (318°W, 43°S) connected the canal Peneus?|
|2031 Aug 20||Ls
|Mars at quadrature. SPC shrinking. Syrtis Major darkens and continues to shrink. W-clouds possible. Surface details increasing in contrast Hellas the features Zea Locus and Alpheus dark? SPC Novissima Thyle (300°-330°W) projection present?|
|2031 Sep 17||Ls 213.3°
|SPC develops dark Magna Depressio at (270°W, 80°S). Syrtis Major narrows rapidly. W-clouds? At 215°Ls Rima Australis (a dark rift) appears connected with Magna Depressio from 20° to 240° longitude; and SPC develops bright projection at 10° - 20° longitude in Argenteus Mons (10°-20°W). Dust cloud in Serpentis-Hellaspontus or Noachis-Hellas? Syrtis Major very narrow?|
|2031 Nov 27||Ls 250°
|Mars at Perihelion. SPC in rapid retreat. Novus Mons smaller. Dust clouds expected over Serpentis-Hellaspontus (Ls 250° - 270°). Syrtis Major beginning to narrow. Frost in bright deserts? Orographic clouds (W-clouds) possible. Elysium and Arsia Mons bright? Note: Several "planet-encircling dust storms have been reported during this season. High probability 255° Ls. (SPC width ~ 24° ±3°).|
|2031 Dec 16||Ls 270°
|Solstice - Northern Winter/Southern Summer. W-clouds present? NPH extends 50° N? Decreased number of White clouds. "Syrtis Blue Cloud"? White areas in deserts? Dust clouds in south until 270° Ls? Watch for planetary system clouds bands. Orographic cloud over Arsia Mons? Syrtis Major is narrow. (SPC width ~ 17° ±2°).|
|2032 Jul 11||Ls 24.1°||Conjunction. Mars is behind the Sun ~2.629AU.|