Two new moons for Jupiter

Feb 10, 2012 By Lillian Oritz, Universe Today
Above are the discovery images for one of Jupiter's newest moons S/2011 J2. This object is faint and doesn't have much visual information, but the moon was discovered using the optical telescope Magellan on Sept. 27, 2011. You can see the motion of the satellite over 40 minutes between the two exposures while the background stars and galaxies do not move. Jupiter is about 0.5 degrees away from the bottom of these images. Credit: Scott Sheppard

Advances in technology have lead to the discovery of new planets outside of our Solar System, and now even new moons in our own backyard.

Last September, two satellites – the smallest ever discovered – were found orbiting Jupiter.

That brings the number of Jovian moons to a whopping 66.  The moons – each about 1 km in size – are very distant from Jupiter. It takes the tiny satellites 580 and 726 days to orbit the gas giant.

The discovery could lead us one step closer to understanding the formation and evolution of our solar system. At least that’s the hope of Scott Sheppard, who works at the the Department of Terrestrial Magnetism at the Carnegie Institution of Science in Washington, D.C. It was Sheppard who, with the help of the massive Magellan telescope at Las Campanas, Chile, initially observed the moons.

“The new satellites are part of the outer retrograde swarm of objects around Jupiter. It is likely there are about 100 satellites of this size around Jupiter,” Sheppard said, explaining that Magellan has made it easier to detect objects further away from Earth. “Up until the last decade, the technology wasn’t there to discover these things because they are very small and very faint.”

Credit: NASA/ESA/E. Karkoschka (U. Arizona)

The two tiny, irregular moons are called S/2011 J1 and S/2011 J2. Thankfully, those names aren’t expected to stick. Once officially confirmed (Sheppard expects it to happen this year), he will have the opportunity to name each. But, Sheppard can’t pick just any moniker. The names, according to the International Astronomical Union, must be related to Jupiter or Zeus, the Roman and Greek mythological figures who served as king of the gods.

Maybe that’s why Sheppard hasn’t yet thought of any names for the soon-to-be members of the Jovian list. Are there any names that haven’t already been chosen? Europa, Thebe, Io, Callisto, Sinope, Ganymede …

Naming requirements will definitely need to change because, as Sheppard explains, there are a lot more moons to discover around some of our other gas – and ice – giants.

“There are a similar amount of objects orbiting Saturn and Neptune, which are more distant from the Sun,” Sheppard said, citing a survey of the sky conducted by the Carnegie Institution of Washington in the early 2000s. “If larger telescopes are built in the future, we’ll be able to discover more of these objects and find out what the objects are like,” Sheppard said.

And finding more of these smaller, distant, irregular satellites is a key to understanding our past.

Here’s why: Irregular satellites are believed to have been captured by their respective planets because the moons typically orbit in the opposite direction of the planet’s rotation, and, they also have eccentric and highly inclined orbits.

Those types of moons differ from regular satellites, which are believed to have formed from the same materials that comprise the planet. That’s because the moons tend to have nearly circular orbits, and, they orbit their respective planets in the same direction that the planet rotates.

A planet can temporarily capture an object, i.e. Shoemaker-Levy 9, but in the present time, “a planet has no known efficient mechanism to permanently capture satellites. Thus, outer capture must have occurred near the time of planet formation when the Solar System was not as organized as it is now,” Sheppard said.

“The orbital history of a satellite can be very complex ... but understanding where a satellite came from can tell us about the formation and evolution of our .”

Explore further: NASA team lays plans to observe new worlds

More information: Click here to learn more about the Carnegie Institution’s Department of Terrestrial Magnetism. For more information about Jovian moons, go to Scott Sheppard’s Jupiter Satellite Page.

add to favorites email to friend print save as pdf

Related Stories

Exomoons could be excellent incubators

Jun 20, 2011

With the arrival of the Cassini–Huygens mission in 2004 to Saturn’s satellite Titan, we terrestrials became acutely aware that similar moons could be orbiting similarly large planets in other solar ...

How many moons does Earth have?

Jan 10, 2012

Look up in a clear night sky. How many moons do you see? Chances are, you’re only going to count to one. Admittedly, if you count any higher and you’re not alone, you may get some funny looks cast ...

'Hot Jupiter' planets unlikely to have moons

Aug 23, 2010

(PhysOrg.com) -- Planets of the major type so far found outside our solar system are unlikely to have moons, according to new research reported in the August 20 issue of The Astrophysical Journal Letters.

Exomoons? Kepler‘s on the hunt

Jan 09, 2012

Recently, I posted an article on the feasibility of detecting moons around extrasolar planets. It was determined that exceptionally large moons (roughly Earth mass moons or more), may well be detectable wit ...

Series of bumps sent Uranus into its sideways spin

Oct 07, 2011

(PhysOrg.com) -- Uranus’s highly tilted axis makes it something of an oddball in our Solar System. The accepted wisdom is that Uranus was knocked on its side by a single large impact, but new research ...

Recommended for you

Video: A dizzying view of the Earth from space

10 hours ago

We've got vertigo watching this video, but in a good way! This is a sped-up view of Earth from the International Space Station from the Cupola, a wraparound window that is usually used for cargo ship berthings ...

NEOWISE spots a comet that looked like an asteroid

10 hours ago

Comet C/2013 UQ4 (Catalina) has been observed by NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft just one day after passing through its closest approach to the sun. The comet ...

What the UK Space Agency can teach Australia

10 hours ago

Australia has had an active civil space program since 1947 but has much to learn if it is to capture a bigger share of growing billion dollar global space industry. ...

Discover the "X-factor" of NASA's Webb telescope

11 hours ago

NASA's James Webb Space Telescope and Chandra X-ray observatory have something in common: a huge test chamber used to simulate the hazards of space and the distant glow of starlight. Viewers can learn about ...

User comments : 7

Adjust slider to filter visible comments by rank

Display comments: newest first

Lurker2358
1.7 / 5 (6) Feb 10, 2012
Still can't explain Uranus.
antialias_physorg
3.7 / 5 (6) Feb 10, 2012
Still can't explain Uranus

What's your problem with Uranus?

And FYI: This is an article about Jupiter and its moons. Not Uranus.
k_m
1 / 5 (2) Feb 10, 2012
Uranus axis of rotation is nearly parallel to the orbital plane, it has retrograde rotation and it's magnetic poles are 40-50 degrees offset from it's geographic poles.

antialias_physorg
5 / 5 (2) Feb 10, 2012
So? Some moons (and Venus) have retrograde rotation. All planets and moons have some deviation of the axis from perpendicular to the plane of orbit. Even on Earth the magnetic poles aren't at the same position as the geographic poles (and have shown signs of wandering/switching throughout history)

None of these features of Uranus particularly unique. Maybe by quantity - but not by quality.
GreyLensman
not rated yet Feb 10, 2012
What's your problem with Uranus?
And FYI: This is an article about Jupiter and its moons. Not Uranus.
Sorry - didn't mean to land that one star on you - bad click skills
Ober
not rated yet Feb 10, 2012
Isn't retrograde orbits, and or highly tilted worlds due to collisions????
Sonhouse
5 / 5 (1) Feb 10, 2012
Yeah but you shoulda seen the other guy....