As regular readers of SPACE.com may already know, this summer Mars will come closer to Earth than at any time in tens of thousands of years. The planet will arrive at opposition to the Sun on Aug. 28, when it will rise at sunset and set at sunrise, as seen from Earth. This opposition occurs less than two days before Mars passes through the perihelion point of its orbit, when it is closest to the Sun.

The minimum distance of Mars from Earth will be less than 34.65 million miles (55.76 million kilometers) at 5:51 a.m. EDT on Aug. 27, when the planets apparent disk diameter will be as great as 25.1 arc seconds, the absolute maximum possible.

While this may seem small, keep in mind that it is an atypically large size for Mars. In fact, For more than two months, from July 23 until September 29, Mars apparent size will exceed 20.8 arc seconds, larger than it has appeared at any time since late October of 1988.

Mars usually grows to such an unusual size at 15- to 17-year intervals, though it will not be approach the Earth more closely until Aug. 28, 2287.

From Aug. 22 through Sept. 3, Mars will blaze at magnitude 2.9, a bit brighter than Jupiter can become at its best, but still inferior to Venus. Mars will then be positioned well to the south within the constellation of Aquarius, the Water Carrier, at a declination of 15.8 degrees.

(Declination is the number of degrees that Mars is located to the south of the celestial equator; on a celestial globe the lines of declination are similar to the lines of latitude found on a terrestrial globe).

When it reaches its highest point in the sky at around 1 a.m. local daylight time, its altitude will be only 27 degrees at Seattle and just 40 degrees at Los Angeles. (A clenched fist held at arm's length represents about 10 degrees on the sky.)

For observers in the far northern United States and southern Canada, Mars will be so low in the sky that atmospheric turbulence will hamper telescopic viewing more than usual, because light from the planet must travel through more of Earth's atmosphere.

On the other hand, amateur and professional astronomers in South America, South Africa and Australia will have an exceptional opportunity, for the planet will pass directly, or very nearly overhead.

Mars has seasons like those of Earth, but they average almost twice as long since Mars takes longer to go around the Sun. This year spring equinox in the Martian southern hemisphere occurred on May 5, and the summer solstice falls on Sept. 29.

Because the Martian South Pole has been tilted toward the Earth since the end of February and will continue that way through the rest of 2003, weve had an excellent view of the south polar cap. The cap appeared at its largest a few months ago, and its subsequent shrinkage has made for interesting viewing ever since.

During June, a residual hood of winter polar cloudiness is in its final process of dissipating. This ultimately will leave the entire south cap shining brilliantly and will allow us to see it undergo noticeable changes during the spring thaw.

Scientists say the polar caps are composed of a mixture of regular snow and ice as well as frozen carbon dioxide, commonly called dry ice.

Around the time that Mars is closest, amateurs with telescopes as small as 4-inches and magnifying above 130-power should be able to make out some dusky markings on the small yellow-orange disk, as well as the bright white of the polar cap.

Those who carry out careful, systematic observations can contribute some useful knowledge about Martian weather and surface conditions. If you carefully observe Mars, you may find it rewarding to sketch what you see, both to create a permanent record and help train your eye to detect elusive detail.

But a bit of caution: Even a large telescope will show neophyte observers little when they first look at Mars.

Even at its closest, the red planet will likely prove to be a challenging object: The disk is relatively tiny and more often than not it will usually be blurred slightly by the Earths atmospheric turbulence, a factor astronomers call "seeing."

If you inspect the planet night after night, however, your eye will gradually become accustomed to the low contrasts and soft boundaries of the disk mottlings. The dark surface markings were once thought by some astronomers to be some sort of vegetation, but flybys of Mars by the Mariner space probes in the 1970s revealed the markings to be nothing more than vast expanses of rock and dust. Windstorms can sometimes shift the dust, resulting in both seasonal and long-term changes.

The most prominent area on Mars is a dark wedge known as Syrtis Major. Its eastern side tends to shrink during the Southern Hemisphere spring, then widens again during autumn.

You soon might also grow familiar with the Martian rotation of 24 hours 37 minutes. As a result, a particular feature comes to Mars central meridian about 40 minutes later than it came the night before. So, it would take a little over a month for a particular feature to come back to the middle of Mars disk if you were viewing it at precisely the same time every night.

The reported Martian canals from the late 19th and early 20th century observations of astronomers such as Giovanni Schiaparelli and Percival Lowell are now known to be unrelated dark spots which were put together as continuous features by the observers eye and mind.

Something certainly got lost in the translation when it came to initially describing the canals.

Schiaparelli was the first to observe the strange lineations on the surface in 1877 and termed them canali, which in Italian meant, "channels." He was misinterpreted, though, and the lines became widely known as canals, a term which suggested that rather a natural phenomenon, that they were constructed by intelligent beings.

Later, Lowell unfortunately took it upon himself to take the matter one step further, expressing an open belief that the canals were constructed by an advanced race of beings who dug them with the intention to bring fresh water down from the poles.

Yellow dust storms tend to begin every Martian year soon after the summer solstice in Mars southern hemisphere. The dust storm season this year should start sometime in early or mid October, though this is far from certain.

A dust storm typically appears quite suddenly as a bright, albeit small, yellow cloud which over a span of days and weeks may ultimately obscure all of Mars for many months at a time, giving the planet the appearance of a blank orange disk.

One of these storms brought great disappointment to many observers at the last favorable Mars opposition in June 2001. Only days after the planets closest approach to Earth, a tremendous dust storm suddenly and unexpectedly broke out, well ahead of schedule, and eventually hid more than 80 percent of the Martian surface for many months. Not since 1971 had such a widespread storm been observed.

Will another such storm develop this year? Well just have to wait and see, as we watch the red disk grow bigger and brighter during the summer of Mars.