If you head outside around 8 p.m. this week and face dueeast, you'll see a brilliant, fiery-colored, non-twinkling "star"that immediately will attract your attention. It's not a star, however, but theplanet Mars.
Mars, the most Earthlike planet of all the planets, has beenabsent from our evening sky for well over a year. Now it's coming back. Here'swhy:
Earth and Mars are in an eternal dance with the two partiessometimes close, sometimes very far apart. Both worlds orbit the sun, withEarth doing so more quickly on the inner path. Every 2.1 years, Earth lapsMars, like a race car on the inside track. At that moment, the sun, Earth andMars are all lined up. Astronomers call it opposition.
During much of January we've been speeding toward Mars inour orbit by an average of 3 miles per second; so Marshas been gradually getting brighter and larger in apparent size.
Mars will pass closest to the Earth at 2:01 p.m. EST duringthe 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 visibleall night). As a bonus, on opposition night, the Moon, just hours beforeofficially turning full, will sit well off to the right of Mars as they climbthe early evening eastern sky.
An "off year" by Mars standards
This year's apparition of Mars is actually one of the poorerand more distant ones in the planet's 15-year cycle of oppositions near andfar. 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 eccentricorbit. So we will come no closer than 61,720,695 miles (99,329,830 km) to it onthis occasion. Shining with a yellow-orange hue, it will attain a peakbrightness of -1.3; just a trifle fainter than Sirius, the brightest star inthe sky. (On this scale, smaller number represent brighter objects, and thebrightest get negative rankings.)
Mars will also be almost twice as far away from Earthcompared to its historic approach to Earth back on Aug. 27, 2003. On that date thered planet made the closest approach to ours in nearly 60,000-years. Ascompared to 2003, the 2010 approach of Mars will provide telescopic viewerswith a very small disk even at high magnification. This will actually be itssecond farthest opposition; the next one, on Mar. 3, 2012 will be the farthest.
So this month's peak brilliance and very modest disk sizewill be the best that Mars achieves until Apr. 2014.
On opposition night, the season is early spring in Mars'northern hemisphere. The Martian north polarcap, tipped 12-degrees toward us, will therefore shrink noticeably in theweeks that follow.
Mars is never easy to study, and this season its smalldiameter presents special challenges. The best telescope for studying the redplanet is a large, high quality refractor or a large aperture Dobsonianreflector. But usually the limiting factor is the atmospheric seeing, which canchange literally from minute to minute. Studying the planets always meansspending a lot of time watching and waiting for elusive moments of steadyseeing. Just as important, the more you look the better trained your eye willbecome. So plan to spend lots of time behind your eyepiece.
This week Mars become just large enough to show touches ofdark surface detail and perhaps occasional white clouds or limb hazes inmedium-sized amateur telescopes at the best moments on those steady nights whenit's high up.
Speaking of high . . .
And now a positive note: this part of Mars' orbit ridesfairly high in the sky for Northern Hemisphere observers; from the southernmostparts of the United States such as south Texas and the Florida Keys, Mars willappear to climb to a point almost directly overhead. This week, the planet isin the midst of performing a backwards (retrograde) loop ? during which it'scarried closest to us ? against the faint stars of Cancer.
Moving from left to right against the background stars, Marswill pass 3-degrees north of the famous Beehive star cluster on Feb. 6, apretty sight in binoculars.
It then slows to a standstill around March 11 and moves backtoward the east. We're then leaving it behind, and henceforth it will appear totravel in a long straight line around the sky, becoming steadily farther andsmaller. It will pass the Beehive again (just 1-degree north of the cluster) onApril 16.
Then on June 6 it slides less than a degree north of thebright bluish star, Regulus, a pretty conjunction easily seen in the middle ofthe evening sky. By then, however, Mars will have shrunk to an ochre dot evenin large telescopes.
The Mars email hoax
Now for something a bit different: over the past six years,people have received an e-mailtitled "Mars Spectacular" which has circulated widely on the Internetfrom an anonymous source. In turn, this message has ended up being passed alongto others who simply couldn't resist forwarding it to their entire addressbook; a snowball rolling down a hill is a good analogy.
This e-mail declares that on Aug. 27, Mars will be closer toEarth than it has in the past 60,000 years, thereby offering spectacular viewsof the Red Planet. The commentary even proclaims, with liberal use ofexclamation marks, that Mars will appear as bright as (or as large as) the fullMoon.
The problem is that "Aug. 27" actually refers toAug. 27, 2003. As I've already noted, Mars did indeed make a historically closepass by Earth on that night. But, to the naked eye Mars merely appeared like abrilliant yellowish-orange star, certainly not anything like the full Moon!
So this Mars e-mail is totally bogus. Yet it now seems thatevery 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 youfind yourself a recipient of this dubious Mars e-mail message, I would suggestthat rather than forward it on to others, you simply hit the "Delete"button on your computer keyboard; better yet, why not forward this columnto the person who may have passed the E-mail on to you. In this way, you'll beproviding an antidote to this Mars computer virus.
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Joe Rao serves as an instructor and guest lecturer at NewYork's Hayden Planetarium. He writes about astronomy for The New York Times andother publications, and he is also an on-camera meteorologist for News 12Westchester, New York.