THE 2013-2014 APHELIC APPARITION OF MARS
By: Jeffrey D. Beish (04-12-2013)

ABSTRACT

Always an intriguing world, Mars offers both casual and serious observers many challenges and delights. It also provides astronomers a laboratory to study the atmosphere and surface of another planet, including the behavior of condensates and their effects on its atmosphere and surface. Mars is similar to Earth in that it has four seasons, exhibits global climates, changing weather patterns, annual thawing and growing of polar caps, storm clouds of water ice, howling dusty winds, and a variety of surface features that predictably change in color and size and appear to shift position over extended periods of time.
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), the International MarsWatch 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 (2001-2012), 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 April 18, 2013 (303° Ls); however, it will not be safe to observe Mars until after June 08, 2013 when it is at least 12 degrees away from the glare of the Sun.

The apparent declination of Mars begins at 21.3° in mid-June 2013 and climbs north of the celestial equator throughout June and mid-July in the constellation Taurus then by August 24, 2013 will enter into Cancer. This is good news for those observing in the Northern Hemispheres because Mars will be seen fairly high in their sky during the early stages of the apparition. Mars will continue to be a few degrees north of the celestial equator passing through Leo September 25, into Virgo on November 25, 2013 until December 17, 2013 when it goes south for the remainder of the apparition.

By January 03, 2014, a ‘0.8’ visual magnitude Mars is seen rising early in the morning sky in the constellation Virgo, it will be at western quadrature  and the phase or terminator will be at 36°. 

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 2013-2014 Mars apparition begins retrogression, or retrograde motion against the background stars ten and a half months after conjunction on March 01, 2014 (96° Ls) and continues through May 20, 2014 (133° Ls).  Each night for this brief period before, during and after opposition the Red Planet will appear to move backwards toward the western sky in the Virgo. The Red Planet will enter into Libra on August 10, 2014, then Scorpius on September 13th, into Ophiuchus on September 25 and into Sagittarius on October 21th. By December 04, 2014 Mars will be in Capricornus. 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 C.F. Capen and modified by J.D. Beish.


2014 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 2014 Mars apparition is considered Aphelic because the orbital longitude at opposition will be only 44° from the aphelion longitude of 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 nearly 12 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 and a half weeks after  retrogression begins. Opposition will occur at 2057 UT on April 08, 2014 (113.7° Ls) with an apparent planetary disk diameter of 15.1 arcsec. Mars will remain visible for more than twelve months after opposition and then become lost in the glare of the Sun around April 30, 2015 as it approaches the next conjunction (June 14, 2015). The cycle is complete in 780 Earth days.

Closest approach occurs at 1254 UT on April 14, 2014 (116.4° Ls) with an apparent planetary disk diameter of 15.2’’ at a distance of 0.617565503 astronomical units (AU) or 57,406,300 miles (92,386,484 km).  During closest approach in 2014 the apparent diameter of Mars will be more than 1.3 arcsec larger than it was at the same period in 2012;  however, it will be nearly 15 degrees lower in the sky – not quite as good 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 2057 UT on April 08, 2014 (113.7° Ls, CM 25.8°)


The observable disk diameter of Mars will be greater than 6 arcsec from December 11, 2013 [1.1° d ] (61.1° Ls) and will not fall below this value until October 08, 2014 (210.1° Ls), lasting 9 months and 27 days or 149 degrees Ls.  Imaging by CCD devices may begin with a disk diameter of 4 arcsec or less, commencing on August 19, 2013.  

The Sub-Earth (De) and Sub-Solar (Ds) points are graphically represented in Figures 4 and 5. The 2013 and 2014 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 December 11, 2013 to a maximum diameter on April 14, 2014, and then shrink as it moves away.  Closest approach occurs on April 14, 2014 (Opposition April 08, 2014).  From January 2014 through Octobber 2014 are the prime observing months. Images shown at 0h UT.


Figure 5. Graphic Ephemeris of Mars during the 2013-2014 apparition from December 12, 2013 through October 06, 2014.   Opposition and 6 arcsec apparent diameter range arc indicated.  Plot illustrates the Declination (black line),   the latitude of the Sub-Earth point (De) or the apparent tilt ( brown line ) in areocentric degrees, and the latitude of the Sub-Solar point ( green 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 December 12, 2013 through October 06, 2014.  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 an excellent view of the prominent north polar cap during most of the 2014 apparition because it will be tilted earthward during the last half of 2013 and through mid-October 2014 when it reaches 0° De. On July 26, 2011 the Martian North Polar Region (NPR) will begin to tilt towards the Earth and will remain so for the remainder of the apparition.  By the second week in September 2013 (20° Ls), the NPC should be free of its hood completely sunlit; however, Mars will be too small to begin micrometer measurements until mid-December. 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 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.


TELESCOPE RESOLUTION TEST

A good time to test for those wishing to see craters on Mars from this planet may want to read about details comparing 1915 apparition with the 2014 apparition go here: Telescope Resolution



CATCH THE PROFILE OF OLYMPUS MONS IN MARS' TERMINATOR

Can you see the outline or profile of the sunlit slope of Olympus Mons as it bisects the phase terminator of Mars during the 2014 apparition. In the mid-1970's the esteemed ALPO Lunar Recorder, John Westfall, published a paper in The Strolling Astronomer challenging observers to measure the illuminated portion of the volcano as it bisects the terminator of Mars [Westfall, 1975, 1976]. John's hypnosis is that the huge volcano should be visible as a relief feature using amateur sized telescopes and during the 2014 apparition this would be a good time to test your telescope, visual observing abilities and electronic digital camera system to detect this volcano as it traverses the terminator of Mars. This author did not believe that this could be accomplished visually; however, using the advanced technology of CCD and/or webcam cameras this would be more likely.

Below is a table of Universal Dates and Times, the phase (i) defect and central meridians (CM) in degrees of the visible portion of Mars from 2014-03-23 until opposition on 2104-04-08.

Table 2. OLYMPUS MONS BISECTING TERMINATOR

References

Westfall, John, (1975), "Observing Olympus Mons in 1975," The Strolling Astronomer (J.A.L.P.O.), Vol. 25, No. 7-8, June 1975, p129-130.
Westfall, John, (1976), "Observing Olympus Mons , Continued, " The Strolling Astronomer (J.A.L.P.O.), Vol. 25, No. 11-12, January 1976, p217.



Table 3. CALENDAR OF EVENTS -- MARS, 2013-2014

DATE PHYSICAL REMARKS
2013 Apr 18 Ls 303° Conjunction. Mars is behind the Sun ~2.431 AU.
2013 Aug 01 Ls 0° 
De 0.0° 
Ds -0.1° 
RA 06:54 
Dec  23.61° 
A.Dia 3.9’’
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.")
2013 Dec 11 Ls 61.1° 
De  24.0° 
Ds 21.5° 
RA 12:08 
Dec 1.1° 
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. 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 ~42° ±4°). 
2014 Jan 01 Ls 70.2° 
De 23.1° 
Ds 23.7° 
RA 12:46
Dec -2.6° 
A. Dia 6.9’’
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 ~33° ±5°
2014 Jan 20 Ls 78.5° 
De 21.4° 
Ds 24.7° 
RA 13:14
Dec -5.3°
A. Dia  8’’
NPC in rapid retreat? Are limb arcs increasing in frequency, iintensity? Antarctic hazes/hood. Cloud activity increases. "Aphelic Chill" in NPR should be ended. (NPC Width ~28° ±4°).

2014 Feb 15 Ls 90° 
De 19.5° 
Ds 25.3° 
RA 13:41
Dec -7.6°
A.Dia 10.1’’
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 ~20° ±4°.
2014 Mar 01 Ls 96.1°
De 19.0°
Ds 25.1°
RA 11:40
Dec 6.1°
A.Dia 11.6’’
Retrogression Begins. Mars begins retrogression, or retrograde motion against the background stars nearly 317 days after conjunction, when it appears to move backwards toward the west for a brief period before, during and after opposition. Watch for dust clouds and possible dust storms. (NPC Width ~19° ±3°).
2014 Apr 08 Ls 113.3°
De 21.4° 
Ds 23.1° 
RA 13:15
Dec -5.3°
A.Dia 15.1’’
Mars at Opposition.  NPC in rapid retreat? 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 ~15° ±2°
2014 Apr 14 Ls 116.1°
De 22.0° 
Ds 22.5° 
RA 13:06
Dec -04.6° 
A.Dia 15.1’’
Mars at Closest Approach. 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° ±2°
2014 May 20 Ls 133.1°
De 24.8°
Ds 18.1° 
RA 12:34
Dec -2.8°
A.Dia 12.9’’
Retrogression Ends. Mars begins westward motion against the background stars. White clouds and ice-fogs frequent. Syrtis Major and Mare Acidalium broad and dark?  Orographic cloud over Olympus Mons.  NPC width ~13° ±1°

2014 Jun 23 Ls 150.1°
De 24.9° 
Ds 12.3° 
RA 12:56
Dec -06.3° 
A.Dia 10’’
Mid-summer. Northern clouds frequent. Syrtis Major maximum width. Are both polar hoods visible?
2014 Jul 29 Ls 169.6° 
De 21.7° 
Ds 4.9° 
RA 12:56
Dec -6.3°
A.Dia 8’’
Late southern winter. Edge of NPH should be visible and the SPH should begin to clear. Hellas frost covered? Are W-clouds present?
2014 Aug 18 Ls 180° 
De 18.0° 
Ds  -0.1° 
RA 14:40
Dec -16.9° 
A.Dia 7.3’’
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" ?
2014 Oct 08 Ls 210.1°
De 4.3°
Ds  -12.4° 
RA 17:01
Dec -24.3° 
A.Dia 6’’
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?  SPC width ~ 49° ±3°
2014 Dec 11 Ls 250.2° 
De -16.1°
Ds -23.7°
RA 20:29
Dec -20.5° 
A.Dia 5’’
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°
2015 Jun 14 Ls 358° Conjunction. Mars is behind the Sun ~2.57AU.