www.starrynight.com | 1December 2007 | Mars Special Feature

A Special Event

At 10 p.m. EST on the night of December 23, the full Moon will pass just north of Mars. In fact, in some partsof the world, the Moon will pass right in front of Mars: northwestern Canada, Alaska, Arctic regions, northernRussia, eastern Europe, and the northeastern British Isles. This will emphasize just how tiny Mars is in comparisonto the Moon, in contrast to the internet hoax which circulates every August about Mars being as big as theMoon!

Now is the Time to ObserveThis December, Mars will be in the same position in the sky as itwas during the legendary apparition of December 1960, whennorthern observers experienced some of the best views of Marsever seen.

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Finding Mars

Where you will find Mars in the sky depends onyour location, the current date, and the time ofnight you’re looking. But there’s an easy, accurateway of finding the Red Planet: use a program likeStarry Night®. It is as simple as telling Starry Night®

your observing location. It will show the sky for thepresent time and date. If you won’t be observinguntil later, change the time accordingly.

Starry Night® will then show you the present positionof Mars, assuming it’s above the horizon. This yearMars is surrounded by a huge ring of the brighteststars in the sky, so it should be easy to spot, evenin a light-polluted city sky.

Mars takes a little more than twice as long as theEarth to make one orbit around the Sun—bothplanets come close to each other once every 26months.

www.starrynight.com | 2December 2007 | Mars Special Feature

Mars rising above the southeastern horizon on the night of closest approach (December 19th) as seen at 11 p.m. EST from mid-northernlatitudes. Even with the naked eye, Mars will be a spectacular sight, ringed by first magnitude stars on all sides, but shining morebrightly than any of them.

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Mars was about as close as it can be to Earth onAugust 2003, about 34.6 million miles (55.7 million km).Twenty-six months later it wasn’t quite as close:43.6 million miles (70.2 million km) on October 29th.This year, Mars will be even farther away: 54.8 millionmiles (88.2 million km).

Is this bad news for Mars observers? Not really: inAugust 2003, Mars was located in Aquarius, reallylow in the sky for northern observers. This year itwill be located in Gemini, almost overhead, and abovemost of the atmospheric turbulence. So, even thoughMars is farther away, and hence smaller in size, itshould actually be easier to see more detail this yearthan in recent years because of steadier images.

Just to clear up a possible point of confusion, the date when Mars is closest to the Earth isDecember 19, but the actual date of opposition(when the Sun, Earth and Mars line up exactly) is 5 days later, on December 24. This difference isbecause Mars’ orbit around the Sun is ellipticalrather than circular, so that it’s a tiny bit closer afew days before opposition.

What to Look For

Like Earth, Mars is tilted relative to its orbital plane,and so it has seasons. Its pole however, points in adifferent direction than the Earth’s, so the seasonson Mars are one season “out of phase” from thoseon Earth. In December 2007, it will be winter inEarth’s northern hemisphere, and so it will be spring

in Mars’ northern hemisphere (and alsoautumn on Mars’ southern hemisphere).

This means that the mists of Mars’North Polar Hood will be dissipating,revealing its bright white North PolarCap underneath, as its northern

hemisphere tilts towards the Sun.

The many space voyages to Mars have shown usthat it is a planet of spectacular topography, fromthe heights of Olympus Mons, the tallest shieldvolcano in the solar system, to the depths of theValles Marineris, a chasm which dwarfs the GrandCanyon. However, seen from the Earth, these featuresvanish because, like our view of the full Moon, thelighting comes from directly overhead, so there areno defining shadows. What we do see is a patternof light and dark, a mosaic of darker bare highlandsand lighter sand-covered lowlands. Most of thesedarker regions are concentrated on Mars’ southernhemisphere.

The most prominent dark markingon Mars is Syrtis Major, located atMartian longitude 290° (map onnext page). It is usually seen as atriangular wedge shape, sometimeswith a curved tip. Between it and thesouth pole is a large bright areacalled Hellas. Extending westwardfrom Syrtis Major is a narrow darkband, Sabaeus Sinus, ending in a forked blob,Meridiani Sinus, so named because it defines the zeromeridian in the Martian longitude system. This isthe area that the Mars Rover Opportunity is currentlyexploring. Further west, at longitude 90°, is SolisLacus, sometimes called “the eye of Mars” becauseof its resemblance to a gigantic eye. West of this iswhat Mars observers often call “the boring side ofMars” because of its lack of dark markings. Studiesof Mars from orbiting space probes reveal otherwise,since this vast plain is the location of Mars’ giganticshield volcanoes. The dark markings begin again ataround longitude 140° with the broad streak of theMare Sirenum. This lies south of the crater Gusev,where the second Mars Rover, Spirit, is on the groundexploring. Mare Sirenum extends westward into MareCimmerium (longitude 230°) and then Syrtis Majorcomes into view again.

www.starrynight.com | 3December 2007 | Mars Special Feature

NASA Jet PropulsionLaboratory (NASA-JPL)

www.starrynight.com | 4December 2007 | Mars Special Feature

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Observing Tips

Mars looks so big and bright to the naked eye, that the view through an amateur telescope mightdisappoint at first. Jupiter has its belts and moons,Saturn has its rings, but Mars looks like nothingmore than a tiny orange dot at first glance. Thereare several secrets to getting Mars to reveal itssights to you.

The first secret is often the hardest to manage: youneed a good telescope. Mars is just about the mostdemanding telescopic object out there, and requiresgood optics. A telescope you pick up at the localmall or off eBay is very unlikely to come close towhat’s needed. Unfortunately many people fall intothis trap and end up with nothing more than a plastictoy. Sad to say, the same amount of money, spentat a store specializing in telescopes, would yield amuch more worthy telescope capable of a lifetime ofsatisfying observing. Since most of us aren’t likelyto find a telescope store at the local mall, you willprobably need to seek out telescope stores online,and one of the oldest and most reliable is OrionTelescopes and Binoculars. The advantage ofany telescope dealer, local or Internet, is that youcan actually talk to them about what you want, andget good solid advice. They want you as a long-termcustomer, and have a vested interest in makingyour first purchase a happy one.

For satisfying views of Mars, a telescope of 4 inches aperture is about the minimum we wouldrecommend. With Mars, as with other astronomicalobjects, aperture rules, and any increase in aperturewill pay real benefits in the quality of the view.

Because of the tiny size of Mars’disk, even at its closest, magnifi-cation is paramount. 200 power isthe minimum with which to see thesurface detail on Mars, and 300power is even better. Good qualityeyepieces are important, andoften a Barlow lens is essentialto get the necessary boost.

Filters are probably more useful for Mars than for anyother planet. Our favorite is the #21 orange or #23Alight red. This tends toenhance the contrast ofMars’ detail and also tocut some of the glarefrom its bright surface. A #80A or #82A mediumblue filter is very useful for enhancing the highclouds that appear above the poles and along thelimb of the planet. Recently several companies,including Orion, have developed special Mars inter-ference filters using the same principles as nebulafilters. These enhance the most interesting featuresof Mars, the dark markings and the clouds, whilereducing the overall glare.

www.starrynight.com | 5December 2007 | Mars Special Feature

Orion’s new Mars Observation Filter Setincludes the three most popular filters forviewing Mars: #21, #82A, and special Marsinterference filter.

Welcome to MarsTraining Camp!

You can have the finest hardware in the store, andyet still have a disappointing first experience withMars. The reason is that your eye and brain needto be trained in order to tease out faint detail at thelimits of visibility. The best way of doing this is tomake drawings of the planet at every opportunity.

“Oh, no,” I hear you cry, “I’m not an artist!” Artisticskill is not a requirement. What you are doing is

attempting to copy, as accurately as you can,what you see on the disk of Mars. At first youwon’t see much, but as you concentrate, you’llsoon be seeing more and more. As with deepsky observing, it sometimes helps to use avertedvision, looking slightly off to one side of the planet.

While an ordinary HB pencil will do, you mayget better results from a softer lead, such as a 2B. An “artist’s stump” very useful. This is atight roll of blotting paper sharpened at bothends, available from any artist’s supply store.You use this to “smudge” the pencil lines, so thatthey take on a more realistic smooth shading.Finally an eraser with a sharp point is useful for removing shading to depict white areas.Ordinary paper will do, but you can organize

your observations better if you use a standardform, such as this one designed by Carlos Hernandez (PDF).

Start your drawing with a circle 40 mm in diameterto represent the disk of Mars. Except when veryclose to opposition, Mars shows a slight phasebecause the sunlight is coming from one side orthe other; draw this in first. Then draw in the areas that change little as Mars rotates, namely the polar

regions. Finally, draw in the darker shadings towardsthe center of the disk, and note the time. This isimportant because Mars is rotating on its axis, andthe apparent positions of surface features changefairly rapidly.

Your first sketches will be rough, but you’ll find thatthey improve with each one you attempt. For eachsketch, record at least the date and time; theobserving form suggests a lot more data that canbe recorded.

If you want to document your observation morethoroughly, use the blanks on the observing form.There are three circles for drawings: the left andright ones are for normal sketches, perhaps withand without a filter, while the middle one is for adiagram using numbers to indicate the darkness offeatures on a scale of 0 to 10. In order to compareobservations around the world, dates and times arerecorded in Universal Time (UT) which is a 24-hourclock based on the prime meridian in Greenwich,England. For example, if you made your drawing at11:30 p.m. EST on December 5th 2007, you wouldconvert this to 04:30 on December 6th in UniversalTime (5 hours later). “Seeing” measures the steadinessof the image, usually with one of scales devised byPickering or Antoniadi:

www.starrynight.com | 6December 2007 | Mars Special Feature

Mars sketches as it appeared in an 8" scope during opposition in 2005, M. Gatto

I Perfect seeing, without a quiver

II Slight quivering of the image with moments of calm lasting several seconds

III Moderate seeing with larger air tremors that blur the image

IV Poor seeing, Constant troublesome undulations of the image

V Very bad seeing, hardly stable enough to allow a rough sketch to be made

Tip: Starry Night® Pro and Pro Plus users canuse the logbook feature in Starry Night® to addobserving notes for Mars. You can also scan yoursketches and add them to your logbook entries.

As the Planet Turns

One final step is needed in order to compare yourdrawing to published maps. You need to knowwhat longitude on Mars was central on the disk at the time you made your drawing. You can dothis easily using the Arkansas Sky Observatory’sMars Physical Ephemeris Calculator. For example,for the drawing mentioned above, enter 12 06 2007and 04h 30m in the ASO calculator, and you get acentral meridian of 94.3°. You can then compareyour drawing to the features visible at that longitudeon the map.

However, for a quick and easy picture of what Marslooked like at the time you made your drawing, checkout a magnified view of Mars in Starry Night® at thetime of your drawing, since the program does all thecalculations for you automatically.

You should only compare your drawing to a mapafter you finish the observation, so as not to beinfluenced by what the map shows. At first, you willprobably see nothing but vague smudges, but aftera week or two of “training,” you should be seeingmuch more detail. Some nights you may see noth-ing at all, and that may in fact be what is reallythere. The problem is with atmospheres: theatmosphere of Earth being unsteady and smearingthe image of Mars, and the atmosphere of Marssometimes carrying widespread dust storms whichblock our view of the surface. An online group likeMarsObservers will keep you abreast of theweather and dust storms on Mars. The finest Marsobservers on Earth post their images and drawingsthere every day, and there’s always lively discussionof current events on the red planet.

A day on Mars, known as a “sol,” is 39 minuteslonger than a day on Earth. This means that if youobserve Mars at the same time each night, the features on Mars will appear to drift in longitudebecause of Mars’ slightly slower rotation rate. Infact it takes about 37 days before you will seeexactly the same face of Mars at the same time.

www.starrynight.com | 7December 2007 | Mars Special Feature

I II III IV V

Mars imaged in June 26, 2001 then again in Sept. 4, 2001while engulfed in a global dust storm. NASA, James Bell (Cornell Univ.), Michael Wolff (SpaceScience Inst.), and the Hubble Heritage Team (STScI-AURA)

Image of a focussed star

Images of Mars

Taking good clear pictures of Mars has long been amajor challenge to both professional and amateurastronomers alike. Making an exposure at the preciseinstant when the atmosphere is absolutely steadyhas been next to impossible. In recent years thishas changed thanks to modern computer technology,and superb images of Mars are being taken regularlyby a large number of amateur astronomers aroundthe world. Their secret weapon is the lowly webcam.Using a webcam, you can make many exposuresof Mars in rapid succession. Some will be good,some will be bad. If you discard the bad ones andcombine the good ones in a computer processcalled stacking, you can produce an image that ismuch sharper than any of the images that wentinto it. Then programs like Adobe Photoshop allowyou to further enhance the contrast and sharpness.The result is images which exceed the quality ofanything that even the pros could manage more thana decade ago; some even come close to imagestaken with the Hubble Space Telescope.

If a simple webcam works well, what happens whenyou redesign a webcam specifically for planetaryimaging? You can find out by using one of several suchdedicated planetary cameras, for example the Orion StarShoot Solar System Color Imager II.

Don’t Give Up!

Although Mars is a challenging object for the amateur astronomer, it is ultimately very rewarding.It is the only planet whose surface we can observedirectly, and it is the planet that most closelyresembles the Earth.

Geoff Gaherty

Geoff has been a life-long telescope addict, and is active inmany areas of visual observation; he is a moderator of theYahoo “Talking Telescopes” and “Marsobservers” groups.

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www.starrynight.com | 8December 2007 | Mars Special Feature

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