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AAAA News and Activities 2003

The Mars Year - 2003
Mars Day on TV - KTVT CBS Channel 11, Dallas
Welcome to Wired News
Wired News: Spending Green to See Red Planet
Annular Eclipse - May 31, 2003
Lunar Eclipse - May 15, 2003
Transit of Mercury - May 7, 2003
Mid-America Astrophysics Conference

The Mars Year - 2003
Mars Day on TV - KTVT CBS Channel 11, Dallas
Welcome to Wired News
Wired News: Spending Green to See Red Planet
Annular Eclipse - May 31, 2003
Lunar Eclipse - May 15, 2003
Transit of Mercury - May 7, 2003
Mid-America Astrophysics Conference

A List of Prominent
Martian Features

Meridiani Sinus
2 degrees

Argyre I
28 degrees

Aurorae Sinus
52 degrees

Aurorae Sinus
55 degrees

Tithonius Lacus
80 degrees

Solis Lacus
96 degrees

Phoenicis Lacus
109 degrees

117 degrees

Arsia Mons
123 degrees

Olympus Mons
136 Degrees

Mare Sirenum
150 degrees

203 degrees

230 degrees

256 degrees

Lunae Lacus
270 degrees

282 degrees

Deltoton Sinus
309 degrees

Sabaeus Sinus
335 degrees

NASA Photo Mars 2001.

Martian Features

Mars shows various features as it rotates on its axis, thus presenting a different face toward Earth over a period of time.
Click on image for Enlarged View

Viewing the Features of Mars

Of all the worlds in the solar system, Mars is most Earthlike. It has ever-changing weather, seasonal thawing of polar ice caps, clouds, vast dust storms, and four seasons. The changes are what you want to observe.

But to recognize changing features on the Martian disk, you will have to learn the dark markings and features that stay the same or change only slowly. These features will serve as your reference marks. Use the maps of Mars that accompany this article to learn these features as Mars approaches Earth this spring. During the three or four months closest to opposition you will be able to spot changing features—clouds, dust storms, the recession of the polar cap—with a skilled and practiced eye.

Astronomers have mapped Mars with a latitude and longitude grid just like the one on Earth, except that longitude runs from 0 degrees to 360 degrees continuously for Mars. The Central Meridian (CM) is the Martian longitude crossing the center of the disk of Mars.

To learn the Martian features, you need only look up the Central Meridian of Mars that’s facing Earth on a given day and hour and compare it to maps and drawings of Mars on this page to know which “face” of Mars you’re looking at.

Mars rotates once on its axis in 24 hours, 37 minutes, and 23 seconds. The Martian day, called a “sol” by space scientists, is thus a bit longer than a day on Earth. Mars turns only 351 degrees of longitude in twenty-four hours. Consequently, if you observe Mars with your telescope at the same time each night, the Martian surface features will have turned 10 degrees less far onto the visible side of the planet. (Thirty-seven minutes later, of course, Mars will be oriented exactly as it was the night before.)

The net effect is that each Martian feature can be seen best every thirty-six days by an observer at a given longitude on Earth, but someone living on the other side of Earth will see the other side of Mars.

Martian Polar Regions

The Martian polar ice caps are bright, easy to see, and undergo fascinating seasonal changes. They thaw in the spring in each Martian hemisphere and re-form each autumn in an annual cycle of the seasons. Mars’ widely varying distance from the Sun strongly affects its seasons. It receives 45% more heat from the Sun when nearest than when farthest.

The southern polar region of Mars will be tilted toward Earth during most of the 2003 apparition. The Martian northern hemisphere winter solstice occurs on September 29, just one month after closest approach to Earth. This means that the south polar cap will be the only one visible during this apparition.

Spring begins in the southern hemisphere on May 5, at which time the polar ice cap should be easily visible. It will slowly melt off during June and July. As the tilt of Mars toward Earth increases, the south polar ice cap will rapidly melt off during the Martian spring. By the time of the August opposition, the ice cap will be only the barest tiny remnant as the Martian summer approaches. Then, as the Martian summer ends as the planet recedes from Earth during our autumn months, the carbon dioxide in the Martian atmosphere in the frigid polar zone will begin to freeze again to the ground as the temperature drops. The south polar cap should remain visible into 2004 as it enlarges at the same time as the separation between Earth and Mars increases during November and December and into next year.

Clouds and Hazes

Mars has an amazingly dynamic atmosphere considering it is less than one hundredth as dense as Earth’s atmosphere. White water clouds, bluish limb hazes, and bright surface ice-fogs and frosts are regularly seen and tracked by Mars observers. Over many years astronomers have learned a lot about when and where these atmospheric features will occur; much of the knowledge is based on observations made with small telescopes.

Orographic clouds form when moist air rises over a high spot. These whitish water clouds form in spring and summer on the upper slopes of the large Martian volcanoes—Olympus Mons, Ascraeus Mons, Pavonis Mons, Arsia Mons, and Elysium Mons—and between Tharsis Tholus and Valles Marineris. Look for orographic clouds using blue and violet filters.

Limb haze appears as a bright, misty arc of light on the sunrise or sunset limb of Mars. It appears at the limb because there the observer looks through a long path in the upper Martian atmosphere, which may contain carbon dioxide crystals, fine dust, cirrus-type water clouds, or a mixture of these. Consequently the presence of limb haze is a very sensitive way to detect unusual weather activity or polar phenomena. When you see haze, note its location, color, and density, as well as the filters used to see it.

Fogs and frosts, often called bright patches, form in the chill of the Martian night, rotate with the planet, bake off in the morning sunlight, and usually disappear by local noon. You can tell them from elevated clouds by examining them with blue, blue-green, and yellow filters. High clouds look brightest with a blue filter, while low-lying fogs look brighter with a blue-green filter than they do in a blue or a yellow filter. Surface frost looks brightest in green and yellow filters and is hard to see with a blue filter. The behavior and location of bright patches also help distinguish these patches from clouds and limb haze. Fogs normally form in valleys, linear depressions, basins, and on upper slopes. Frosts are usually seen on deserts, plateaus, mountains, and floors of large craters. Pinpointing the location and seasonal occurrence is important to the study of Martian weather patterns.

Mars normally shows only a bright, featureless disk in violet light because the Martian atmosphere scatters short wavelengths. When a violet clearing occurs, the large, dark surface features can be seen through the atmosphere with a Wratten 47 filter. Although the debate over the cause of this phenomenon has raged for decades, no explanation of violet clearing is generally accepted.

Dust Storms

Observations of Mars indicate that yellow dust storms occur around the time of southern summer solstice, soon after Mars reaches perihelion. During the opposition in June 2001, dust storms broke out in the Hellas basin just after the planet’s closest approach to Earth. This dust storm quickly spread to the whole surface of Mars. This was the biggest dust storm seen on Mars in three decades. It is unlikely that two major dust storms will occur on successive apparitions. Still, because little is known about the cause of Martian dust storms and how they develop, it is impossible to predict what will happen.

AAAA Mars Card

The AAAA Mars Card is a concise way to learn the essential information about Mars during the current favorable opposition in August and September 2003. Just click on either image to down load our PDF, print it off, and make copies for yourself and to hand out at your own Mars Observing Events for friends and the general public!
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Planning for the Public

In planning any special Mars observing activities for the general public or the media, keep in mind that in late August when Mars is closest (diameter about 25 arc sec), it will only rise about 30 degrees above the horizon at midnight ... so not good for "early evening" observing. However, this situation improves through September: at end of September, Mars will still be over 20 arc sec. in diameter, but will cross the meridian (a bit more than 30 degrees high) earlier ... about 9:30PM. This placement is somewhat better for public programs.

As always, there is the danger of planet-wide dust storms at this perihelion. Storm activity on Mars will easily wipe out any surface features otherwise visible.

The Planetary Society has proclaimed August 27, 2003, the date of opposition, as "Mars Day". The Planetary Society has a goal of "half of the world's population looking at, or thinking about, Mars" on Mars day. So please circle this day on your calendar. Now is the time to start planning Mars Parties in your local area.

Oppositions of Mars 1988-2003

This chart by C.F. Chapin shows the relative positions of Mars and Earth for the years 1988 to 2003. The last great opposition of Mars was 1988. On August 28, 2003, Mars will be at its closest approach to Earth in recorded history, at a distance of only 34,646,418 miles.

Click on image for enlarged view

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