September 21, 2017

Astro-Event: The Rise of Mars & Opposition of 2012.

Mars during the 2003 opposition, nearly twice as large as this years!

(Photo by Author).

After a wintertime drought of evening planets, March and the beginning of northern hemisphere spring sees the return of the classical naked eye-planets to the PM skies, not the least of which is Mars. Currently rising low in the east at sunset in the constellation Leo, Mars reaches opposition this weekend on March 3rd at 20:00UT/15:00EST at a distance of 0.6741 Astronomical Units (A.U.s) or 62,661,510 miles from Earth. This coming month will be the best time to view the Red Planet, and this week we’re giving you the low down on “all things Martian”.

First, the bad news; Mars just passed aphelion, or its farthest point on its markedly elliptical orbit on February 15th, only 17 days prior to opposition. To top it off, we passed just the opposite point in our orbit, or Earthly perihelion in early January. This means that the opposition of 2012 will be particularly unfavorable. At its closest, Mars doesn’t quite break an apparent size of 14” (13.9” to be precise), the worst since 1995 (at 0.676 A.U.s distant) and farthest “near-point” until 2027 at 0.678 A.U.s away. This isn’t far off from farthest possible opposition of 0.683 A.U.s that could occur with Earth at perihelion and Mars at aphelion;

Mars Oppositions from 2001-2029 (Graphic by Author).

Year Angular Diameter
2001 20.8″
2003 25.1″
2005 20.2″
2007 15.9″
2010 14.1″
2012 13.9″
2014 15.2″
2016 18.6″
2018 24.3″
2020 22.6″
2022 17.2″
2025 14.6″
2027 13.8″
2029 14.5″

You’ll note, however, that in the current epoch, the perihelion points of the two planets aren’t lined up precisely, though apsidal precession (an ingredient in the Milankovitch cycles) would cause this to occasionally occur over long timescales.

Now, a strike in favor of the good guys; Mars is at a northern declination of +10° degrees during opposition; the last time that an opposition occurs with a higher northern declination is 2022 with a declination of +25°. This means that Mars will ride high overhead and be visible the entire night, great for imaging and viewing from northern latitudes.

One minor point to clear up about opposition this year; March 3rd isn’t quite Mars’s nearest approach to Earth, although many unenlightened news agencies who have just axed their science departments will tout it as such. That occurs about 45 hours later on March 5th at 17:00UT/12:00 EST at a slightly closer distance of 0.6737 A.U.s or 62,624,327 miles distant. Why the 37,182 mile difference? Well, keep in mind that Mars just passed aphelion and is now moving towards perihelion on January 24th, 2013. Meanwhile, we’re moving towards Mars after passing perihelion in January towards aphelion in summer. Mars takes 1.88 years to make one orbit, and we “catch up” to it racing around the inside track about every 2.13 years. Also remember Kepler’s 2nd Law; planets move faster near perihelion, that’s why consecutive oppositions are only on average 2.13 years apart! The last opposition occurred on January 2010 in the constellation Cancer, and the next won’t occur until April 8th, 2014. Note that oppositions move eastward through about 1/7th of the sky from one to the next, and come roughly back to the same place in right ascension on a 15 year cycle. For example, the 1997 opposition occurred just across the Leo border into Virgo, very near this year’s, and the 2027 one 15 years from now will be very near the bright star Regulus (Alpha Leonis). Note that Mars oppositions will also get steadily better from 2012, with an excellent opposition on July 27th, 2018 that’s nearly as favorable as the 2003 opposition… will the “Mars Hoax Email” also make a dreaded comeback?

So, what can YOU expect to see during the opposition of 2012? Well, one of the simplest observations that you can make is with the naked eye; what color does Mars appear to you? Although its often touted as the “Red Planet,” Mars can actually run the gamut from yellow-to-orange with perhaps reddish tints, depending on the amount of dust suspended in its atmosphere. It is currently northern summer on Mars (in fact, the northern summer solstice for the planet also occurs this month) and the planet experiences harsher and longer southern hemisphere winters, as explained in this excellent video on Martian seasons from the Planetary Societies’ Emily Lakdawalla;

It isn’t at all likely that a northern hemisphere dust storm will occur at opposition this year, but its often worth noting if Mars looks a little “sickly yellow…” as occurred during the excellent 2003 opposition, when Mars dazzled at magnitude -2.9, about 5 times brighter than this year. I typically see a dust-free Mars as “pumpkin orange”… others have described it as “candy apple red” or “sherbet yellow.” Feel free to insert your own favorite-tasting descriptor. A painter’s color wheel may even help to compare and  discern the “true shades of Mars”.

The Moon & Mars in 2011 (Photo by Author).

Through binoculars, Mars just begins to show a tiny dot of a disk. A fun project to try near opposition would be to spot the planet in the daytime with the Moon nearby as occurs on March 7th. I once accomplished this feat during the opposition of 2003, about 10 minutes prior to local sunset. (True story: I’ve planned vacations and time off around oppositions of Mars!) Can you pick out Mars with binoculars? How ‘bout with the naked eye?

A shrinking Mars. (Created by the author with Starry Night).

Even at low power, some details on the Martian surface can be seen. The disk of Mars will again fall below 10” by May 1st, so March-April is the best time to observe the planet. For an animation of how Mars “shrinks” in 2012, click here. In fact, observational astronomers throughout history typically only turned their attention to the Red Planet around opposition. Percival Lowell, the famous “canal-hunter of Mars” made his final series of observations of Mars from the Lowell observatory in Flagstaff, Arizona during the 1916 aphelic opposition that had very similar circumstances to this year’s showing.

The first thing any observer will note is the large northern polar cap. Unlike the southern cap typically tilted towards us during perihelic oppositions, the northern cap won’t shrink to near invisibility and should remain visible throughout the season. Alternating areas of dark and light patches are also apparent at higher power; don’t be afraid to “crank up the magnification” on Mars as it approaches the celestial meridian offering its best views through local midnite. Keep in mind that the Martian “day” is about 39 minutes longer than our own. This means that if you observe Mars at the same time every evening, its globe has only rotated only 1/37th, or not quite 10° degrees. Mars Previewer II is an excellent, simple program to discern just what region you are currently seeing.

A page from the Astroguyz “Mars sketch log”.

Sketching can be an excellent way to get to know the Red Planet. In addition to following in the foot-steps of those astronomers of yore, sketching is a great way to train your eye to pick out minute detail and serves as a fun diary. In addition to visual observation, many backyard observers use modified webcams to take images that would have been the envy of many observatories only decades ago. Another fun project for those with large light buckets is our ongoing hunt for the elusive Martian moons discovered by Asaph Hall from the United States Naval Observatory during the favorable (0.377 A.U.) opposition of 1877.

It’s no coincidence that the rover Mars Curiosity is currently headed towards the Red Planet at this time. Launched in November 2011 to the fanfare of a #NASATweetup, an Earth departure a few months prior to opposition assures a quick, minimal energy trajectory. Thus, roughly every 2+ years, Earth “invades Mars”. Sadly, the failed Russian Phobos-Grunt mission didn’t make the trip. Although every Mars mission to date has been an “opposition class” mission, some interesting proposals have been made for a longer (1,000 days+!) Douglas class “solar conjunction” manned mission… we’re going through the trouble, why not stay for awhile?

RAD in the laboratory… (Credit: NASA/JPL).

But Curiosity hasn’t been idle enroute to Mars; its Radiation Assessment Detector (RAD) has been sampling the radiation environment that a Mars-bound astronaut would be exposed to on an interplanetary journey. In fact, a large solar flare swept over Curiosity just last week and this is just the sort of stuff we need to know if humans are to ever set foot on Mars. All eyes will be on Curiosity as it makes its spectacular sky-hook-style landing on August 5th-6th 2012.

WASH ME… an Opportunity self portrait. (Credit: NASA/JPL).

In other Mars news, the Mars rover Opportunity is looking a bit dusty as it heads into southern hemisphere winter at Meridiani. Opportunity is 2,788 Sols “past warranty” as of this writing and is still relaying data concerning the Martian rotation and the planet’s interior from its stationary “winter over” site on the Cape York/Endeavour Crater rim. Keep Opportunity in mind this opposition season; we have an active embassary “up there,” and are about to add one more!

Need some Martian Sci-Fi to make opposition season complete? How about the classic H.G. Wells War of the Worlds broadcast? Some of our faves are Tim Burton’s tribute to corny Sci-Fi with Mars Attacks! And Arthur C. Clarke’s Report on Planet Three, a short story where Martian scientists argue against the possibility of life… on Earth! Good hunting, and let us hear of your Mars-spotting adventures!

 

Comments

  1. Andrew Symes says:

    I’m going to be coming back to this again & again – so much info here. Thanks for posting!

  2. Ed Kotapish says:

    Agreed Andrew!

    Dave always presents opportunities to view and explore the interesting, rare, and challenging aspects of the hobby. Keep ‘em coming Dave.

  3. I look forward to watching more of your videos. I’d never seen images of clouds on Mars. fascinating.

Trackbacks

  1. [...] 3rd: Mars reaches opposition, an unfavorable one in the constellation Leo due to the fact that aphelion for the Red Planet [...]

  2. [...] Mars is currently tiny, at only 5.7” arc seconds across and about 90% illumination, a far cry from opposition earlier this year. Conventional wisdom is that Mars generally doesn’t show much surface detail in a [...]

  3. [...] it’s worth noting that after a series of bad oppositions in 2010 and 2012, oppositions in 2014 and 2016 are trending towards more favorable. In fact, the Mars opposition of [...]

  4. [...] it’s worth noting that after a series of bad oppositions in 2010 and 2012, oppositions in 2014 and 2016 are trending towards more favorable. In fact, the Mars opposition of [...]

  5. [...] shine at magnitude -1.5 and present a 15.2” disk, only slightly larger than the near minimum apparition of 2012, when it appeared 13.9” across. This is a far cry from the historic 2003 appearance, when Mars [...]

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