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An artist's depiction shows the rings of planet J1407b. Its rings are eclipsing a star.
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(CNN)In
1610, after he built his telescope, Galileo Galilei first spotted
enormous Saturn's gigantic rings. More than 400 years later, astronomers
have in a sense dwarfed that discovery with a similar first.
Using powerful optics, they have found a much larger planet-like body, J1407b, with rings 200 times the size of Saturn's, U.S. and Dutch astronomers said.
It lies some 400 light-years away from Earth.
For
decades, scientists have believed that many moons around large planets
formed out of such ring systems. But this is the first one astronomers
have observed aside from Saturn's, they said.
It was discovered in 2012, but a detailed analysis of its data was recently completed and published.
Dominating the sky
If J1407b were in our solar system, it would dominate Earth's nightly sky.
"If
we could replace Saturn's rings with the rings around J1407b, they
would be easily visible at night and be many times larger than the full
moon," said Matthew Kenworthy from the Netherlands' Leiden Observatory.
Unlike Galileo peering a relatively short
distance through his simple telescope, today's astronomers can't eyeball
the rings hundreds of light-years away.
But
using two very powerful optical devices with eight cameras each, they
can observe the effect the rings have as they pass across nearby star
J1407 -- written without a 'b' at the end.
It is similar to our sun. The rings of planet J1407b eclipse its light.
56-day eclipse
With the enormous size of the rings, the eclipse the astronomers observed lasted 56 days.
But
the star did not go completely dark for nearly two months. Some of
J1407b's 30 rings are denser, blocking more light, and some of them are
less dense, letting more light through.
And
there are gaps between the rings, leading the scientists to theorize
that "exomoons" have formed and cut clean orbits through the debris,
like the moons around Saturn.
Our own solar system's ringed giant has at least 60 moons, according to NASA.
Bigger than a planet
Like
its system of rings, planet J1407b is also much larger than Saturn,
said astrophysicist Eric Mamajek, whose team at the University of
Rochester discovered the object. "You could think of it as kind of a
super Saturn."
It is called a brown dwarf, a size classification somewhere between a planet and a star, according to the California Institute of Technology.
Brown dwarfs are hot but don't burst into nuclear fusion the way stars do, so they don't give off light.
The
scientists are calling on amateur astronomers to keep an eye on star
J1407 in hopes they may observe the rings eclipsing it again and report
the results to the American Association of Variable Star Observers, which collects astronomical data on "stars that change in brightness."
And astronomers will also search for more such ringed systems.
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