If you head outside around 8 p.m. this week and face due east, you'll see a brilliant, fiery-colored, non-twinkling "star" that immediately will attract your attention. It's not a star, however, but the planet Mars.
Mars, the most Earthlike planet of all the planets, has been absent from our evening sky for well over a year. Now it's coming back. Here's why:
Earth and Mars are in an eternal dance with the two parties sometimes close, sometimes very far apart. Both worlds orbit the sun, with Earth doing so more quickly on the inner path. Every 2.1 years, Earth laps Mars, like a race car on the inside track. At that moment, the sun, Earth and Mars are all lined up. Astronomers call it opposition.
During much of January we've been speeding toward Mars in our orbit by an average of 3 miles per second; so Mars has been gradually getting brighter and larger in apparent size.
Mars will pass closest to the Earth at 2:01 p.m. EST during the American afternoon of Jan. 27, just two days before its Jan. 29 opposition, (when it will appear to rise at sunset and set at sunrise and will be visible all night). As a bonus, on opposition night, the Moon, just hours before officially turning full, will sit well off to the right of Mars as they climb the early evening eastern sky.
An "off year" by Mars standards
This year's apparition of Mars is actually one of the poorer and more distant ones in the planet's 15-year cycle of oppositions near and far. This is due chiefly to the fact that just over two months after opposition, Mars will arrive at aphelion (its farthest point from the sun) in its eccentric orbit. So we will come no closer than 61,720,695 miles (99,329,830 km) to it on this occasion. Shining with a yellow-orange hue, it will attain a peak brightness of -1.3; just a trifle fainter than Sirius, the brightest star in the sky. (On this scale, smaller number represent brighter objects, and the brightest get negative rankings.)
Mars will also be almost twice as far away from Earth compared to its historic approach to Earth back on Aug. 27, 2003. On that date the red planet made the closest approach to ours in nearly 60,000-years. As compared to 2003, the 2010 approach of Mars will provide telescopic viewers with a very small disk even at high magnification. This will actually be its second farthest opposition; the next one, on Mar. 3, 2012 will be the farthest.
So this month's peak brilliance and very modest disk size will be the best that Mars achieves until Apr. 2014.
On opposition night, the season is early spring in Mars' northern hemisphere. The Martian north polar cap, tipped 12-degrees toward us, will therefore shrink noticeably in the weeks that follow.
Mars is never easy to study, and this season its small diameter presents special challenges. The best telescope for studying the red planet is a large, high quality refractor or a large aperture Dobsonian reflector. But usually the limiting factor is the atmospheric seeing, which can change literally from minute to minute. Studying the planets always means spending a lot of time watching and waiting for elusive moments of steady seeing. Just as important, the more you look the better trained your eye will become. So plan to spend lots of time behind your eyepiece.
This week Mars become just large enough to show touches of dark surface detail and perhaps occasional white clouds or limb hazes in medium-sized amateur telescopes at the best moments on those steady nights when it's high up.
Speaking of high . . .
And now a positive note: this part of Mars' orbit rides fairly high in the sky for Northern Hemisphere observers; from the southernmost parts of the United States such as south Texas and the Florida Keys, Mars will appear to climb to a point almost directly overhead. This week, the planet is in the midst of performing a backwards (retrograde) loop ? during which it's carried closest to us ? against the faint stars of Cancer.
Moving from left to right against the background stars, Mars will pass 3-degrees north of the famous Beehive star cluster on Feb. 6, a pretty sight in binoculars.
It then slows to a standstill around March 11 and moves back toward the east. We're then leaving it behind, and henceforth it will appear to travel in a long straight line around the sky, becoming steadily farther and smaller. It will pass the Beehive again (just 1-degree north of the cluster) on April 16.
Then on June 6 it slides less than a degree north of the bright bluish star, Regulus, a pretty conjunction easily seen in the middle of the evening sky. By then, however, Mars will have shrunk to an ochre dot even in large telescopes.
The Mars email hoax
Now for something a bit different: over the past six years, people have received an e-mail titled "Mars Spectacular" which has circulated widely on the Internet from an anonymous source. In turn, this message has ended up being passed along to others who simply couldn't resist forwarding it to their entire address book; a snowball rolling down a hill is a good analogy.
This e-mail declares that on Aug. 27, Mars will be closer to Earth than it has in the past 60,000 years, thereby offering spectacular views of the Red Planet. The commentary even proclaims, with liberal use of exclamation marks, that Mars will appear as bright as (or as large as) the full Moon.
The problem is that "Aug. 27" actually refers to Aug. 27, 2003. As I've already noted, Mars did indeed make a historically close pass by Earth on that night. But, to the naked eye Mars merely appeared like a brilliant yellowish-orange star, certainly not anything like the full Moon!
So this Mars e-mail is totally bogus. Yet it now seems that every year in the late spring or summer, this "Mars chain letter" gets revived.
So . . . I would like to make a request: If later this year you find yourself a recipient of this dubious Mars e-mail message, I would suggest that rather than forward it on to others, you simply hit the "Delete" button on your computer keyboard; better yet, why not forward this column to the person who may have passed the E-mail on to you. In this way, you'll be providing an antidote to this Mars computer virus.
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Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.