Comet McNaught C/2009 R1 streaks across the sky in 2009 (file photo); Image courtesy Michael Jäger
for National Geographic News
Published June 15, 2010
A bright green comet is streaking across early morning skies this week, experts say.
Comet McNaught C/2009 R1 has been steadily gaining brightness and will be most brilliant through June 16, during its closest approach to Earth at about 105 million miles (170 million kilometers) away.
Some predictions say the comet—best seen from the Northern Hemisphere—could be at least as bright as the stars that make up the familiar Big Dipper constellation.
C/2009 R1, already visible to the naked eye as a faint, fuzzy ball low in the northeastern sky, is best seen in the hour before the sun rises, said Anthony Cook, an astronomical observer at Los Angeles’s Griffith Observatory.
"Because it has a hazy outline, it should be observed from as far away from light pollution as possible," Cook said.
(Read about a green, two-tailed comet seen in 2009.)
"Between now and the 24th of June, it’s visible in a moon-free sky, but after the 26th it will be too close to the sun to see."
Comet McNaught’s Superlong Tail Promises Flashy Show
The intensity of brightness seen in comet McNaught C/2009 R1—named after the Australian astronomer Robert McNaught who first spotted it in September 2009—only occurs once every four years or so, Cook said. (Learn about the “age of comets.”)
Another comet also named by the astronomer, McNaught C/2006 P1, put on a spectacular show in 2007. It was later discovered to be one of the biggest and brightest known comets.
As C/2009 R1 nears the sun, its ice melts, releasing gas and dust that stream away into space. (Explore an asteroids and comets interactive.)
This reaction forms a distinctive blue tail of ionized carbon monoxide stretching a million miles (about 1.6 million kilometers) long. Through binoculars, the tail appears about the same length as the width of the full moon in the sky.
Meanwhile, the comet’s nucleus is only a few miles across, with a surrounding glowing greenish cloud of gas that is about 250,000 miles (400,000 kilometers) across—roughly the distance from Earth to the moon.
Cook predicts the especially bright C/2009 R1 will put on a worthy show for the unaided eye.
for National Geographic News
Published June 10, 2010
They’re not the most aww-inspiring baby pictures, but new infrared images prove the youngest known planet outside our solar system does in fact exist—and that planets can grow up fast—a new study says.
Probably only a few million years young, Beta Pictoris b is already fully formed, despite standard models that say such a planet should take ten million years to reach “adulthood,” researchers say. The planet breaks the record once held by the planet BD 20 1790b, which clocked in at 35 million years old.
The new planet is also nearer to its parent star than any other known planet outside our solar system—about as close as Saturn is to our sun.
Located about 63.4 light-years from Earth, that star, named simply Beta Pictoris, is similar to our own star. And like Beta Pictoris b, Beta Pictoris is relatively young—about 12 million years old, compared with the sun’s 4.5 billion years.
(Related: “Newborn Planet Is Youngest Ever Found" .)
First Direct Evidence of Youngest Planet
Previous pictures—including Hubble Space Telescope images released in 2006—had revealed that an orbiting disk of dusty debris, likely created by the collisions of young asteroids and planets, surrounds Beta Pictoris.
A gap in the disk, which resulted in a ring around the star, had suggested that a Jupiter-like “gas giant” planet was sweeping through. But the existence of the planet wasn’t confirmed until the European Southern Observatory’s Very Large Telescope captured the new pictures in 2009.
Crucially, The 2009 images show the young planet at a different point in its orbit than in a cryptic 2003 picture of the same star system (see above right). As such, the images seem to prove that the 2003 picture did in fact capture a planet and not, say, a background star.
(Read about an 2006 report suggesting Beta Pictoris could spawn carbon-rich planets.)
The infrared pictures make clear that Beta Pictoris b, which is about nine times more massive than Jupiter, is not only a real exoplanet—a planet outside our solar system—but a fully formed one (see an interactive graphic showing the known exoplanets and how they’re found).
"It’s the first time we have direct proof of the time scale to form a planet—the first proof to say a planet can form rapidly," said study leader Anne-Marie Lagrange of the Astrophysics Laboratory of Grenoble in France.
(Related: “New Planets Found; Have Backward Orbits.”)
Beta Pictoris a Boon to Planet Hunters?
Lagrange believes that stars with debris rings make “nice places to look for planets.”
She’s not convinced, though, that all rings around stars are proof of planets. By gravitationally yanking out masses of debris from a disk, a flyby from a nearby star could also create rings, she said. (Get more facts about the universe.)
Separating planet-neighboring rings from the other types of rings should get easier after 2012, when the Atacama Large Millimeter Array (ALMA) radio telescopes—more sensitive than current arrays—are scheduled to go online in Chile.
When it comes to planet hunting, Lagrange added, the pace of technology has been impressive.
"We are just now starting to be able to make direct images of exoplanets," she said. "We get very different information now, and in a few years’ time we may even be able to look inside the atmospheres of these planets."