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 (2029-2035), 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.

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 September 23, 2036 (95.4° Ls); however, it will not be safe to observe Mars until after October 29, 2036 when it is at least 12 degrees away from the glare of the Sun.

The apparent declination of Mars begins at -14.7° by the second week in April 2037 in the constellation Capricornus and will ascend north into the constellation Aquarius by April 21, 2037 and then into Pisces on May 31. Mars will be south of the celestial equator until June 12, 2037 when it will then cross north of the celestial equator. This is not good news for those observing in the Northern Hemispheres because Mars will be seen fairly low in their sky during the first half of the apparition. Good news for southern hemisphere observers however.

By July 31, 2037, a '-0.2' visual magnitude Mars will be seen rising early in the morning sky in the constellation Aries and it will be at western quadrature with the phase defect or terminator of 47.1°.   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 2037-2038 apparition of Mars begins retrogression, or retrograde motion against the background stars eleven months after conjunction on October 12, 2037 (310° Ls) and continues through December 23, 2037 (349.7° 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 Taurus and Aries. 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 2037 Aphelic Apparition of Mars. Original graph prepared by C.F. Capen and modified by J.D. Beish.

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 2037 Mars apparition is considered Transitional (between Aphelic and Perihelic) because the orbital longitude at opposition will be 98.3° from the Aphelion longitude of 70° Ls and 81.7° 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.

Closest approach occurs at 0800 UT on November 11, 2037 (327.4° Ls) with an apparent planetary disk diameter of 19'' at a distance of 0.4935838 astronomical units (AU) or 45,881,480 mi (73,839,085-km). During closest approach in 2037 the apparent diameter of Mars will be 5.6 arcsec smaller than it was at the same period in 2035; however, it will be 28.2 degrees higher in the sky - good for observing the Red Planet for observers in the northern hemispheres of Earth. 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 0904 UT on November 19, 2037 (331.9° Ls, CM 267.8°)

The observable disk diameter of Mars will be greater than 6 arcsec from April 17, 2037 [-14.7° δ] (200.1° Ls) and will not fall below this value until March 31, 2038 (36.8° Ls)), lasting nearly 12 months or 197 degrees Ls. Imaging by CCD devices may begin with a disk diameter of 4.5 arcsec or more, commencing on or about January 30, 2037.

The Sub-Earth (De) and Sub-Solar (Ds) points are graphically represented in Figures 4 and 5. The 2037-2038 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 April 17, 2037 to a maximum diameter of 19" at closest approach on November 11, 2037 and then shrink as it moves away. Images shown at 0h UT.

Figure 5. Graphic Ephemeris of Mars during the 2037-2038 apparition from April 17, 2037 through March 31, 2038. Opposition November 19, 2037 (331.9° Ls) and 6 arcsec apparent diameter range are 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 April 17, 2037 through March 31, 2038. Opposition November 19, 2037 (331.9° Ls) and 6 arcsec apparent diameter range are 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.

Astronomers will have a view of both polar regions during this apparition. From the second week in April 2037 the Martian South Polar Region (SPR) will be positioned to be seen from the Earth and will remain so until mid-March, 2038. Also, during the first week of September 2037 the North Polar Region (NPR) positioned to be seen from the Earth For more detailed information on both polar regions click the north polar cap and south polar cap.

Observers should be aware that during the next apparition of Mars in 2037 a major dust storm may occur to block our view of the clouds and surface of the Red Planet. While it is nearly impossible to predict these events our studies show that the Martian dusty season should begin on or about February 14, 2037 (165° Ls) through January 10, 2038 (359° Ls) with the highest probability around the second week in July (255° Ls) and again peaking October 20 (315° Ls). Massive, planet-encircling storms usually occur in the southern hemisphere summer and usually in sensitive areas for the development of dust storms are in northwest Hellas. For more detailed information on Martian dust storms on this web site.