During August 2003, we experienced the last close approach of our planet to Mars. The hoopla reached gigantic proportions. “The best Martian apparition in 60,000 years,” screamed the NASA press release. Internet rumors suggested that Mars would be “as big as the full moon,” which was of course ridiculous. Mars is only twice the diameter of the moon, and the moon is only a quarter of a million miles away. Even at its closest, Mars is just a tad under 34 million miles away.
Even so, people wait between 13 and 17 years to get a good view of the red planet, so Perkins Observatory scheduled 10 straight nights of Mars observations. Every one of those nights was packed to the rafters.
We tried to lower expectations but to no avail. My frank appraisal of the telescopic view seemed at odds with the astronomical hype.
What folks saw was a red dot with a white polar cap flickering in and out of visibility through Earth’s turbulent atmosphere. A few greenish markings were visible on the planet’s surface.
Fifteen years have passed, and now Mars is making another close approach. The current opposition, as they are called, will peak on July 31, which just happens to be my last day as director of Perkins Observatory. On that night, Mars will be 35.8 million miles from Earth. However, it will be worth a look all through the month of August as it slowly recedes from Earth.
Mars is worth a look in a telescope because of the rarity of such close approaches. However, the simple fact is that Mars never fails to disappoint. And there are reasons why it will be even more disappointing this time around.
For one thing, Mars will be somewhat farther away than its apparition in August 2003. A million miles or so might not seem like much, but when you’re talking about a planet that is 4,000 miles wide (tiny Earth is twice its diameter), it makes a pretty big difference.
Also, this time around, from our latitude, Mars doesn’t get very far above the turbulent atmosphere close to Earth’s horizon. The image will shimmy and shake most of the time. You’ll have to stare at it for a minute or two hoping that the atmosphere settles down for a few seconds of a clear view.
And then there are the dust storms. Mars has an exceedingly thin atmosphere, but it can kick up powerful winds. Without warning, a planetwide yellow dust storm can obscure the view for weeks.
Mars is in the midst of a huge dust storm right now, so for an indeterminable period, you can forget about seeing surface features like its mysterious green markings.
If you’d like to take a look, Perkins Observatory will be doing its regular Friday night programs. They begin promptly at 9 p.m., and prearranged tickets are strongly recommended. Please call Don Stevens at 740-363-1257 for further details or to reserve tickets.
If Mars leaves you cold, we’ll also be able to show you brilliant Venus in its half Venus phase, Jupiter with its dark cloud bands and its four brightest moons, and lovely Saturn, rings no extra charge.
The program on Aug. 3 is particularly dear to my heart. It’s just a few days past opposition, and I’ll be giving my “farewell” lecture at Perkins. So come on down!
Alternatively, you can dust off that telescope, large or small, that has been languishing in your attic and feast your eyes on the red planet.
Right now, start looking low in the southeast around 11 p.m. The best time to observe Mars is around 1 AM. when it has reached its highest point in the south. Sadly, that highest point is just 26 degrees above the horizon. (For reference, straight overhead is 90 degrees above the horizon.)
By the last week in August, “Old Red” will have receded a bit to 40.5 million miles away, but it will still be worth a look. Start observing in the southeast at 10 p.m. The best views will be around 11 a.m. when Mars is again at its highest point in the south.
The first thing you’ll notice, even without a telescope, is that Mars is not particularly red. The issue is more one of contrast. Red is a difficult color to see in the low-light circumstances provided by the nighttime sky. Anything with a vaguely yellow cast looks red to the die-hard stargazer.
In a telescope, Mars looks a lot redder, courtesy of the Martian soil, which is seasoned liberally with iron oxide, also known as rust. Mars’ atmosphere is barely there at all — an exceedingly thin blanket of carbon dioxide. Any oxygen that might have helped to thicken the atmosphere a little is tied up in the soil as rust or has spun off into space.
If the Martian atmosphere is quiet, hope that our Earthly air isn’t moving around. A turbulent atmosphere above your observing location will turn Mars into a fuzzy blob. If the image of Mars is sharp at low magnification, keep increasing the power until you begin to lose surface detail.
You may see a brilliantly white Martian polar cap or two or some of its mysterious green marking. The markings aren’t really green. They only look green by contrast with the red of the Martian soil.
As telescopes got more powerful over the course of the 20th century, those green marking produced a good deal of weird speculation. More on that next week.
Tom Burns is director of the Perkins Observatory in Delaware.