Astronomers have found the most conclusive evidence yet that a large watery ocean lies beneath the surface of Jupiter’s moon Ganymede…With the discovery, Ganymede joins Enceladus and Europa as another moon in the solar system with a confirmed subterranean ocean.
“The solar system is now looking like a pretty soggy place,” said Jim Green, director of planetary science at NASA. “The more we look at individual moons, the more we see that water is really in enormous abundance.”
And where there’s water, there’s a chance of life.
Scientists have suspected for decades that a subterranean ocean might slosh between the rocky mantle and icy crust of Ganymede, the largest moon in our solar system, but they had not been able to prove it definitively until now.
Using the Hubble Telescope, a team of researchers has detected slight fluctuations in two bands of glowing aurorae in Ganymede’s atmosphere that they say could occur only if the moon contained a salty body of water…
Saur figured that…regular shifts in Jupiter’s magnetic field would affect the position of the aurorae in Ganymede’s atmosphere differently depending on whether or not the moon has a subsurface ocean.
Computer models show that if Ganymede did not have a subsurface ocean, the changes in Jupiter’s magnetic field should cause the bands of hot, electrically charged gas to rock six degrees over a 10-hour period. However, if the moon contained a salty ocean, it would reduce the rocking of the auroras to just two degrees.
The reason for the difference is that a saltwater ocean is electrically conductive and creates a secondary magnetic field that would suppress the effects of Jupiter’s magnetic field.
Saur looked at measurements taken by the Hubble Telescope in 2010 and 2011 of auroras over both the north and south poles of Ganymede and saw that the auroras only moved two degrees over a seven-hour period…
As astronomers continue their search for life elsewhere, this technique could help them to identify what other bodies might harbor water and, perhaps, life forms beyond Earth.
Interesting stuff. Yes, I’d love to be in on the trip to Ganymede for a walkabout. See if we can find some subsurface beachfront property.
Firing off a string of snapshots like a sports photographer at a NASCAR race, NASA’s Hubble Space Telescope captured a rare look at three of Jupiter’s largest moons parading across the banded face of the gas-giant planet: Europa, Callisto, and Io.
These so-called Galilean satellites (named after the 17th century scientist Galileo Galilei, who discovered them with a telescope) complete orbits around Jupiter ranging from 2 days to 17 days in duration. They can commonly be seen transiting the face of Jupiter and casting shadows onto its cloud tops. However, seeing three moons transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade…
Missing from the sequence is the moon Ganymede, which was outside Hubble’s field of view and too far from Jupiter in angular separation to be considered part of the conjunction.
For the first time in almost a decade, sky-watchers this week will be able to see all five naked-eye planets over the course of one night for several nights in a row.
The classical naked-eye planets—Mercury, Venus, Mars, Jupiter, and Saturn—can be seen easily without optical aids and so have been known since ancient times. But the quintet hasn’t appeared together during a single night since 2004.
What’s more, this week’s parade of planets will be joined in the nighttime skies by the waxing crescent to waxing gibbous moon and the superbright stars Sirius and Canopus…
Although the moon and the seven bright objects will all be visible in one night, they won’t all appear at the same time or in the same region of the sky.
The best time to catch sight of the cosmic parade will be between February 28 and March 7. This is when the more elusive planets Mercury and Mars will be at their brightest in the evening sky for 2012, and when the moon will be above the horizon for many hours before setting…
“The moon, of course, is our closest cosmic neighbor and the only one we can really study as a world with the naked eye or even simple binoculars…However these other points of light are all really bright objects in the sky too, so to get the full experience, take your time and let your eyes adapt to the darkness and enjoy..” said Geza Gyuk, an astronomer with the Adler Planetarium in Chicago.
RTFA for suggestions in where to look and when. Enjoy. I hope you live somewhere with little light or no pollution.
Sorry, Northern Hemisphere only. :)
NASA’s Dawn spacecraft has returned the first close-up image after beginning its orbit around the giant asteroid Vesta. On Friday, July 15, Dawn became the first probe to enter orbit around an object in the main asteroid belt between Mars and Jupiter.
The image taken for navigation purposes shows Vesta in greater detail than ever before. When Vesta captured Dawn into its orbit, there were approximately 16,000 kilometers between the spacecraft and asteroid. Engineers estimate the orbit capture took place at 10 p.m. PDT Friday, July 15.
Vesta is 530 kilometers in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes have obtained images of Vesta for about two centuries, but they have not been able to see much detail on its surface.
“We are beginning the study of arguably the oldest extant primordial surface in the solar system,” said Dawn principal investigator Christopher Russell from the University of California, Los Angeles. “This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta’s history, as well as logging the onslaught that Vesta has suffered in the intervening eons…”
Although orbit capture is complete, the approach phase will continue for about three weeks. During approach, the Dawn team will continue a search for possible moons around the asteroid; obtain more images for navigation; observe Vesta’s physical properties; and obtain calibration data…
Rock on, folks! Keep us ordinary folks up with what we need to keep our space curiosity bump happy.
A vast cosmic collision that left a dark scar the size of the Earth on the surface of Jupiter has been discovered by an amateur astronomer using a home-made telescope.
Anthony Wesley spotted the extraordinary impact on Sunday night while watching Jupiter from the backyard of his rural home in Murrumbateman, near Canberra, Australia. He nearly missed it because he was also watching the final rounds of the Open Championship on television.
Mr Wesley, 44, an IT consultant who designed his telescope himself, told The Times how he saw a strange black blob creep across the planet’s surface.
“About 11pm I went inside to have a break and watch the golf, and by the time I came back out at about 1am the impact point had rotated around into view,” he said. “I couldn’t believe it. I thought, ‘That wasn’t there before’, and then I realised Jupiter had actually been hit by something.”
Mr Wesley immediately set about alerting professional astronomers to his discovery, some of whom trained more powerful telescopes on Jupiter after seeing his e-mailed images.
Scientists at Nasa confirmed that his observations were of an impact rather than a storm. It is thought to have been caused by a small comet or cometary fragment, about 1km in diameter, which would have struck the planet at a speed of about 60km per second (about 135,000mph)…
Were an object of similar size to strike the Earth, it would cause devastation, though not quite over so large an area. Jupiter’s greater gravity will have magnified the effects.
Ian Crawford, lecturer in planetary sciences at Birkbeck, London, said: “Even if the impact would not have been quite so bad on Earth, it underscores the danger to us of such impacts. We wouldn’t want to be hit by a 1km fragment: it would be devastating. You’d expect it to excavate a crater 20km across…”
Mr Wesley, an IT consultant, said that he spends at least 20 hours a week looking at Jupiter — his “main passion” in the sky.
When asked to explain the appeal of Jupiter, the fifth planet from the Sun and the largest in the solar system, Mr Wesley said: “It’s just such a dynamic planet.
“Even when there are no earth-shattering events happening it just changes day to day and has so many patterns it is fascinating to watch.”
Bravo! Good for you, dude.
Hmm. That’s about how much time I spend each week – online.
Venus and Jupiter, the two brightest planets, have been marching toward each other for more than a month in the southwestern sky at dusk. As they’ve drawn closer together, the sight has been catching more people’s eyes, and now the show is reaching its climax.
This evening, weather permitting, you will see Venus and Jupiter blazing about a finger’s width apart at arm’s length. Look early enough and, far to their lower right, you can find the crescent moon just above the horizon…
Monday night brings the peak of the show. The two planets will remain as close as ever, and the moon will form a compact, extraordinary triangle with them.
The moon is currently 1.4 light-seconds distant, Venus is 8.4 light-minutes distant, and Jupiter is 42 light-minutes away. That’s how long the light from each has been traveling through space before it hits your eye.
The last paragraph is for folks with a 2-dimensional brain.