Wednesday, September 22, 2010

Looming Disappointment: Jupiter is Big, but it’s Not a Big Deal

Is it a bird?  A plane? A star? No, it’s a distant gas giant.

If you’re watching the night sky this month, you’ll see a bright spot rising in the east as the sun sets in the west.  It’s the planet Jupiter, and it’s making its usual pass by Earth at closer-than-usual distance, drawing much attention from the media.  Mention it to astronomers, however, and you be subject to bored stares.  

A Google search for “Jupiter” brings up over 400 articles for the month of September, many with phrases like “celestial treat” and “rare phenomenon.”  All the major news institutions have covered it, including the New York Times and National Geographic. predicts, “It should be a stunning sight.”  

Professor Tom Bania of Boston University’s Department of Astronomy doesn’t see what the fuss is about.  His office sits just below the Judson B. Coit Observatory, where he’d have access to views of this “celestial treat,” if he’d bother.  The Earth comes relatively close to Jupiter every year, and although this year is a bit closer than most, Bania’s not expecting anything spectacular:

“Are we going to learn the secrets of the universe?  No.  Are astronomers throwing Jupiter-parties?  No. It’s a media hype thing.”  

Jupiter is the fifth planet from our sun, an enormous, whirling gas giant that has at least 63 moons, four of which were originally discovered by Galileo in 1610.  It is best known for its huge red spot, a centuries-old storm on its southern end that is physically larger than the planet Earth.  

(Artistic rendering.  The green ones are moons.)  

Once a year, the Earth lies right in the middle of a straight shot between the sun and Jupiter, and this is called Jupiter in “opposition.”  This year’s opposition happens to occur when Jupiter is orbiting closer to the sun, and thus closer to Earth than any year since 1963, but the difference is minuscule in planetary terms.  During last year’s opposition, Jupiter was 374,426,315 miles away, and this year it’s 367,547,580 miles away.  Ultimately, it’s less than a two percent difference.    

Professor John Clarke of the Center for Space Physics at the university compares the opposition event to a birthday.  “It’s significant as a historical marker, but nothing’s changed from the day before and nothing’s going to change the day after.”

While Clarke has focused much of his research on Jupiter, he’s far more interested in Jupiter’s ability to protect the Earth from interstellar asteroids, thanks to its much greater gravitational pull that draws objects toward it and away from us.   Scientifically, he says, this year’s opposition just isn’t a big deal.  

Bania worries that this type of hype draws attention away from new and important findings.  “We’re in a genuine age of discovery,” he says, but he’s afraid that real breakthroughs might get lost in the media cloud.

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