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Sent primarily to investigate the origin and evolution of Jupiter, Juno has been able to take in bonus observations of the planet's four major moons - Callisto, Ganymede, Europa and now Io. It performed its close flyby of Ganymede in 2021, and of Europa earlier this year. These passes produced some novel insights from Juno's microwave radiometer. Intended to look deep into the clouds of Jupiter, this instrument has also been able to see down through the ice layers of Ganymede and Europa for tens of kilometres. These two moons are of particular interest because they're both thought to hide...

One of Jupiter's tenuous rings can be seen in this infrared image. (NASA/ESA/CSA/STScI/Judy Schmidt) Given its similarities to its neighbor, Saturn, it seems natural to ask why Jupiter doesn't also have a magnificent, extensive system of visible rings. Alas, it's not the reality. While Jupiter does have rings, they're thin, tenuous, flimsy things of dust, visible only when back-lit by the Sun. According to new research, these discount rings lack bling because Jupiter's posse of chonky Galilean moons keep discs of rock and dust from accumulating the way they do around Saturn. "It's long bothered me why Jupiter doesn't have...

Saturn's rings, Titan and the much smaller moon Enceladus. (NASA/JPL/Space Science Institute) ===================================================================== On human timescales, things in the Solar System seem to be pretty set in place. Over cosmic timescales, it's all gradually falling apart. The planets are very, very slowly moving away from the Sun; and most of the moons are slowly moving away from their planets in a process called tidal acceleration. The fact that Titan is slowly moving away from its planet - Saturn - is therefore not at all unusual. But astronomers have found something really surprising: Titan's outward migration is faster than expected -...

NASA has a message for space lovers this month: Look up. The largest planet in the solar system, Jupiter, will be clearly visible June 10 — and to see its biggest moons you'll only need to grab a pair of binoculars. NASA said the gas giant is at its "biggest and brightest this month" and will be visible all night. The planet will reach opposition, the annual occurrence when the Jupiter, Earth and the Sun are arranged in a straight line, with Earth in the center. So, mark your calendars for Monday, as it will be the best time of...

NASA’s Galileo spacecraft surprised scientists when it revealed that Jupiter’s moon Ganymede generated its own magnetic field. But new research shows Ganymede also creates incredibly powerful waves that rocket particles to enormous energies. Scientists revealed these huge electromagnetic waves while studying old data from Galileo, which orbited Jupiter from 1995 to 2003. The observations show another wild way that a moon can interact with the magnetic field of its planet. Jupiter’s radius is around 11 times that of Earth, but it is perhaps 20,000 times more magnetic. This generates an intense radiation environment around the planet. Typically, these waves around...

Within the Jupiter system, there are 67 confirmed moons of varying size, shape and composition. In honor of Jupiter’s namesake, they are sometimes collectively referred to as the Jovians. Of these, the four largest – Io, Europa, Ganymede and Callisto – are known as the Galileans (in honor of their founder, Galileo Galilei). These four moons are among the largest in the Solar System, with Ganymede being the largest of them all, and even larger than the planet Mercury. In addition, three of these moons – Europa, Ganymede and Callisto – are all believed or known to have interior oceans...

Explanation: Some of the Solar System's largest moons rose together on February 23. On that night, a twilight pairing of a waning gibbous Moon and Jupiter was captured in this sharp telescopic field of view. The composite of short and long exposures reveals the familiar face of our fair planet's own large natural satellite, along with a line up of the ruling gas giant's four Galilean moons. Left to right, the tiny pinpricks of light are Callisto, Io, Ganymede, [Jupiter], and Europa. Closer and brighter, our own natural satellite appears to loom large. But Callisto, Io, and Ganymede are actually...

Disgraced Planned Parenthood official Deborah Nucatola’s shocking personal work history is coming to light. Records reveal that Nucatola was employed by a former White House staffer at the time that she was selling aborted baby fetus parts. A staunch political advocate, Nucatola railed against the “right-wing” Bush administration. What’s more, she so enjoyed her work in the abortion industry that she touted a T-shirt celebrating a drug used in the practice. Let’s break it down: Works for a White House staffer Nucatola is currently employed at Sexual Health Innovations, founded by former Obama White House staffer Jessica Ladd. Senior Obama...

Explanation: On June 30, Venus and Jupiter were close in western skies at dusk. Near the culmination of this year's gorgeous conjunction, the two bright evening planets are captured in the same telescopic field of view in this image taken after sunset from Bejing, China. As the two bright planets set together in the west, a nearly Full Moon rose above the horizon to the south and east. Imaged that night with the same telescope and camera, the rising Moon from the opposite part of the sky is compared with the planetary conjunction for scale in the digitally composited image....

Explanation: Our solar system's ruling giant planet Jupiter and 3 of its 4 large Galilean moons are captured in this single Hubble snapshot from January 24. Crossing in front of Jupiter's banded cloud tops Europa, Callisto, and Io are framed from lower left to upper right in a rare triple-moon conjunction. Distinguishable by colors alone icy Europa is almost white, Callisto's ancient cratered surface looks dark brown, and volcanic Io appears yellowish. The transiting moons and moon shadows can be identified by sliding your cursor over the image, or following this link. Remarkably, two small, inner Jovian moons, Amalthea and...

Angelenos will get their chance Friday to witness a rare celestial event when the shadows of three of Jupiter’s largest moons will fall upon Jupiter at the same time. Griffith Observatory will stay open one hour later than normal to allow visitors who are already at the park to watch the triple-shadow transit as Jupiter’s three moons – Io, Europa, and Callisto – will cross the planet’s disk throughout the evening. Three moon shadows will not appear simultaneously on Jupiter again, from Los Angeles, until 2032, according to the Observatory. As if the triple shadow transit weren’t enough, there will...

Explanation: A 24 minute sequence from top to bottom, this intriguing series of telescopic frames tracks the occultation of Io by Callisto, two of Jupiter's Galilean moons, from San Pietro Polesine, Italy, planet Earth. A challenging observational project using a small telescope, the two contrasting Jovian worlds are both slightly larger than Earth's Moon. In fact, bright, volcanic Io and dark, cratered Callisto are about 3,640 and 4,820 kilometers in diameter respectively. With Earth itself now crossing near the orbital plane of Jupiter's moons, astronomers are enjoying a season of Galilean moon mutual events ranging from eclipses to occultations. The...

Scientists have long wondered why Jupiter's once-twin moons, Ganymede and Callisto, came to be so different. Ganymede, the larger of the two, has a rocky core and scars from geologic trauma spread across its face. Callisto's center is a mix of ice and rock. Its ancient surface is heavily pocked with impact craters. What happened? Comets, says Southwest Research Institute's Amy Barr, lead author of a paper published in this week's Nature Geoscience that shows how differences in the frequency and strength of comet impacts explains the moons' distinctive histories... Ganymede, located about 500,000 miles closer to giant Jupiter than...

The plume is seen as an umbrella-shaped feature in the long exposure image to the right Nasa's New Horizons spacecraft has sent back images of a huge volcanic eruption on Jupiter's moon Io.A massive dust plume, estimated to be 150m (490ft) high, can be seen erupting from the Tvashtar volcano on Io. On Wednesday, the US probe flew by Jupiter, using the planet's gravity to boost its speed, reducing the travel time to its ultimate target of Pluto. New Horizons also took photos of the icy moons Europa and Ganymede in the run-up to its encounter with Jupiter. Turning...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2003 February 27 When Moons and Shadows Dance Credit & Copyright: Wes Higgins Explanation: It's no wonder Jupiter is a favorite target for even modest earthbound telescopes. The most massive planet in the solar system with four of the largest moons also boasts the famous Great Red Spot, a giant hurricane-like storm system over three hundred years old. Recorded on December 15, 2002 between 7:19 and 8:40 UT,...