NASA's Juno mission page

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The Juno Mission

JUNO MISSION LOG

Infographic: Juno, Built to Withstand Intense Radiation Environments

Juno has been headed for Jupiter since 2011 to study the gas giant’s atmosphere, aurora, gravity and magnetic field.

 This infographic illustrates the radiation environments Juno has traveled through on its journey near Earth and in interplanetary space.

All of space is filled with particles, and when these particles get moving at high speeds, they’re called radiation.

 NASA studies space radiation to better protect spacecraft as they travel through space, as well as to understand how this space environment

 influences planetary evolution. After Jupiter orbit insertion on July 4, 2016, Juno will have the chance to study one of the most intense radiation 

 environments in our solar system.

Citizen-scientists Matt Brealey and Gustavo B C processed this color-enhanced image
 of a Jupiter storm using data captured on Feb. 7, 2018, by the JunoCam imager aboard NASA's Juno spacecraft.
Credit: Matt Brealey/Gustavo B C/NASA/JPL-Caltech/SwRI/MSSS

JunoCam took this image during its eleventh close flyby of Jupiter on February 7, 2018.
 Image credit: NASA / JPL / SwRI / MSSS / David Marriott.

In preparation for the imminent arrival of NASA’s Juno spacecraft in July 2016,

 astronomers used ESO’s Very Large Telescope to obtain spectacular new infrared images

 of Jupiter using the VISIR instrument. This false-colour image was created by selecting

 and combining the best images obtained from many short VISIR exposures at a wavelength of 5 micrometres.

 Image credit: ESO/L. Fletcher.

False colour images generated from VLT observations in February 2016 (left) and March 2016 (right),

showing two different faces of Jupiter. The bluer areas are cold and cloud-free, the orangey areas are warm and cloudy,

 more colourless bright regions are warm and cloud-free, and dark regions are cold and cloudy (such as the Great Red Spot 

 and the prominent ovals). The wave pattern over the North Equatorial Band shows up in orange.

 These views were created from VLT/VISIR infrared images. The orange images were obtained at 10.7 micrometres wavelength 

 and highlight the different temperatures and presence of ammonia.

 The blue images at 8.6 micrometres highlight variations in cloud opacity.

 Image credit: ESO/L. Fletcher.

This view compares a lucky imaging view of Jupiter from VISIR (left) at infrared wavelengths with a

 very sharp amateur image in visible light from about the same time (right).

 Image credit: ESO/L. Fletcher/Damian Peach.

Home/News/Juno gets the first-ever view of Jupiter's North Pole
Juno gets the first-ever view of Jupiter's North Pole
Some never-before-seen features come to light.
By Carl Engelking  |  Published: Friday, September 02, 2016

Even from afar, we always knew Jupiter was a bit of an oddball, and upon closer examination we were correct.

On Aug. 27, NASA’s Juno spacecraft, with all its instruments blazing, swooped within 2,500 miles of the Jovian surface

 and beamed back the first-ever images of its north pole. It was the first of 36 planned flybys planned for the mission,

 so there’s plenty more where this came from. Still, even from the first 6-megabyte download, Jupiter’s revealing

 why it’s unlike any other planet in our solar system.

An infrared glimpse at Jupiter’s south pole.

 (Credit: NASA/JPL-Caltech/SwRI/MSSS)

“First glimpse of Jupiter’s north pole, and it looks like nothing we have seen or imagined before,”

said Scott Bolton, principal investigator of Juno from the 

Southwest Research Institute in San Antonio in a press statement Friday September 02, 2016.

Juno probe peers below Jupiter's clouds 

This image from Juno’s JunoCam captured the south pole in visible light only. 
It’s a puzzle why the north and south poles are so similar, yet have a different number of cyclones.
 Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles 
 Credit bbc.com"

GAZE IN WONDER AT JUPITER’S MYSTERIOUS GEOMETRIC POLAR STORMS

This wondrous image of Jupiter's south pole shows the arrangement of cyclones
 that is unique in our Solar System: five circumpolar cyclones perfectly arranged 
 around a single polar cyclone.
 Image: NASA/SWRI/JPL/ASI/INAF/IAPS

This composite imageshows the central cyclone at the planet’s north pole 
and the eight cyclones that encircle it. 
Credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM.
 This is hardly the orange, white and saffron belted world we are familiar 
 with from telescope views of the lower latitudes. The scale of these storms is, 
 as you would expect with Jupiter, quite impressive. Alberto Adriani is a Juno co-investigator
 based at the Institute for Space Astrophysics and Planetology in Rome:

This image captures the swirling cloud formations around the south pole of Jupiter, 
looking up toward the equatorial region.
NASA’s Juno spacecraft took the color-enhanced image during its eleventh close flyby
 of the gas giant planet on Feb. 7, 2018 at 7:11 a.m. PST (10:11 a.m. EST). 
 At the time, the spacecraft was 74,896 miles (120,533 kilometers) from the tops of Jupiter’s clouds
 at 84.9 degrees south latitude.
Citizen scientist Gerald Eichstädt processed this image using data from the JunoCam imager.
 This image was created by reprocessing raw JunoCam data using trajectory and pointing data
 from the spacecraft. This image is one in a series of images taken in an experiment to capture
 the best results for illuminated parts of Jupiter's polar region.
To make features more visible in Jupiter’s terminator — the region where day meets night — 
the Juno team adjusted JunoCam so that it would perform like a portrait photographer
 taking multiple photos at different exposures, hoping to capture one image with the intended light balance.
 For JunoCam to collect enough light to reveal features in Jupiter’s dark twilight zone, 
 the much brighter illuminated day-side of Jupiter becomes overexposed with the higher exposure.
JunoCam's raw images are available for the 
public to peruse and process into image products at:
       
More information about Juno is at: and here

Image credits: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt

For almost 200 years humans have been watching the Great Red Spot (GRS) on Jupiter and wondering what’s behind it.
 Thanks to NASA’s Juno mission, we’ve been getting better and better looks at it. New images from JunoCam 
 reveal some of the deeper detail in our Solar System’s longest-lived storm.

Images of Jupiter’s Great Red Spot have gotten better over the decades.
 On the left is an image from the Voyager mission, middle is an image from the Galileo mission,
 and on the right is a Hubble Space Telescope Image.
 Image: NASA/ESA/Evan Gough

JunoCam image of the Great Red Spot showing:

 (A) compact cloud clusters;
 
 (B) mesoscale waves;
 (C) spiraling vortices;
 
 (D) a central turbulent nucleus;
 (E) examples of elongated thin dark gray filaments.

 Image: NASA/A. Sanchez-Lavega et. al.

The study identifies five different morphological features in the Great Red Spot.
 From top to bottom:
 

 compact cloud clusters
 mesoscale waves
 spiraling vortices
 
 the central turbulent nucleus
 and large dark thin filaments
 Image: American Astronomical Society/Sanchez-Lavega et al.

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Infographic: Juno, Built to Withstand Intense Radiation Environments -
PHOTO MONTAGE OF THE LAUNCH

Technician’s install Juno’s titanium vault. (Image Credit: NASA/JPL-Caltech/LMSS)

The JUNO ProBe on it's way to Florida

Exploded diagram of the Juno Probe

Atlas Rocket Ready to launch

Juno Mission Clearing the Lightning Rod's Towers

Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at

 Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof.

 Credit: Ken Kremer/

Juno Mission on the way!!!

Juno Mission Launch Vehicle Diagram

NASA prepares its Jupiter probe JUNO for arrival blogger-avatarby Jon Fingas July 08, 2015

It's been a long time in coming, but NASA's Juno probe is finally close to reaching Jupiter.

NASA reports that the spacecraft is "on track" to arrive on July 4th, 2016 (how American!), 

and that the ground crew is tweaking the flight plan to at once give Juno more time and complete tasks ahead of schedule.

The ship's initial orbit is splitting into two in order to test instruments before the science gathering starts.

 Also, it'll take 14 days to complete an orbit rather than the originally planned 11.

   [Image credit: NASA/JPL-Caltech]

NASA prepares its Jupiter probe JUNO for arrival blogger-avatarby Jon Fingas July 08, 2015

Since its launch five years ago, there have been three forces tugging at NASA's Juno spacecraft 

as it speeds through the solar system. The sun, Earth and Jupiter have all been influential --

 a gravitational trifecta of sorts. At times, Earth was close enough to be the frontrunner. 

 More recently, the sun has had the most clout when it comes to Juno's trajectory. 

 Today, it can be reported that Jupiter is now in the gravitational driver’s seat,

 and the basketball court-sized spacecraft is not looking back.

The Juno spacecraft will enter orbit around Jupiter on July 4, 2016,

 picking up the exploration efforts NASA's Galileo mission began 20 years ago.

Illustration of NASA’s Juno spacecraft firing its main engine
to slow down and go into orbit around Jupiter.
Lockheed Martin built the Juno spacecraft for NASA’s Jet Propulsion Laboratory.

Protecting Juno’s Heart by EVAN GOUGH on NOVEMBER 4, 2015

A computer-generated image of the Juno spacecraft. NASA/JPL-Caltech

Uploaded on Jun 28, 2011
Find out more at Here

and HERE
Juno's unique polar orbit is the key to the mission's design. What's so special about it?
Credit: NASA/JPL/SwRI Category Science & Technology License Standard YouTube License

Juno spacecraft and its science instruments. Image credit: NASA/JPL

Juno orbital graphic

This annotated color view of Jupiter and its four largest moons -- Io, Europa, Ganymede and Callisto --

 was taken by the JunoCam camera on NASA's Juno spacecraft on June 21, 2016, at a distance of

 6.8 million miles (10.9 million kilometers) from Jupiter. 

 Image credit: NASA/JPL-Caltech/MSSS

Illustration of NASA's Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter.
Lockheed Martin built the Juno spacecraft for NASA's Jet Propulsion Laboratory.
Credit: NASA/Lockheed Martin

Published on Jun 23, 2016 Secrets lie deep within Jupiter, shrouded in the solar system's strongest magnetic field
and most lethal radiation belts. On July 4, 2016, NASA's Juno spacecraft will plunge into
uncharted territory, entering orbit around the gas giant and passing closer than any spacecraft before.
Juno will see Jupiter for what it really is, but first it must pass the trial of orbit insertion.
For more information: and here Category Science & Technology License Standard YouTube License

JUNO CAPTURES A STUNNING JOVIAN ‘PEARL’ December 2016

New Juno image of Jupiter taken on Dec. 11, 2016. Processed by Damian Peach

This is the original image sent by JunoCam on Dec. 11 and features the eighth
 in a string of large storms in the planet’s southern hemisphere. 
 Credit: NASA/JPL-Caltech/SwRI/MSSS

4-frame animation spans 24 Jovian days, or about 10 Earth days. The passage of time is accelerated
 by a factor of 600,000. Some of the ovals are visible as well as a variety of jets
 – west to east and east to west.
 Credit: NASA

JUNO BUZZES JUPITER A MERE 4,300 KM’S ABOVE THE CLOUD TOPS

Illustration of NASA's Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter.
 Lockheed Martin built the Juno spacecraft for NASA's Jet Propulsion Laboratory. 
 Credit: NASA/Lockheed Martin

False color view of Jupiter’s polar haze, created by citizen scientist Gerald Eichstädt
 using data from the JunoCam instrument. 
 Credit: NASA/JPL-Caltech/SwRI/MSSS/Eric Jorgensen

To accomplish its science objectives, Juno is orbiting Jupiter’s poles and passing very close to the planet,
 avoiding the most powerful (and hazardous) radiation belts in the process. 
 Credit: NASA/JPL-Caltech

Juno’s Latest Close Flyby of Jupiter on This Week @NASA – February 3, 2017

Published on Feb 3, 2017
NASA’s Juno spacecraft made its latest close flyby of Jupiter Feb. 2 -- passing about 2,700 miles above the planet’s clouds. 
This was the fourth close flyby since Juno began orbiting Jupiter last year on July 4. During these close passes instruments
 on the spacecraft probe beneath the cloud cover to collect scientific data about the planet's structure,
 atmosphere and magnetosphere. This information could help us better understand the planetary systems being discovered around other stars.
 Also, Cassini Sees Saturn’s Rings in Greater Detail, The Most Extreme Blazars, NASA at Super Bowl Event,
 NASA at NBA Black Heritage Celebration, and
Day of Remembrance!
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JUNO WILL GET NO CLOSER TO JUPITER DUE TO ENGINE TROUBLES

Jupiter’s south pole. captured by the JunoCam on Feb. 2, 2017, from an altitude of about 62,800 miles (101,000 kilometers)
 above the cloud tops.
 Credits: NASA/JPL-Caltech/SwRI/MSSS/John Landino

This amateur-processed image was taken on Dec. 11th, 2016, at 9:27 a.m. PST (12:27 p.m. EST),
 as NASA’s Juno spacecraft performed its third close flyby of Jupiter.
 Credits: NASA/JPL-Caltech/SwRI/MSSS/Eric Jorgensen

Jupiter: Into the Unknown (NASA Juno Mission Trailer)

Published on Jun 23, 2016
Secrets lie deep within Jupiter, shrouded in the solar system's strongest magnetic field and most lethal radiation belts.
 On July 4, 2016, NASA's Juno spacecraft will plunge into uncharted territory, entering orbit around the gas giant and passing 
 closer than any spacecraft before. Juno will see Jupiter for what it really is, but first it must pass the trial of orbit insertion.
  For more information:
Category
Science & Technology
License
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Published on Feb 3, 2017
NASA’s Juno spacecraft made its latest close flyby of Jupiter Feb. 2 -- passing about 2,700 miles above the planet’s clouds. 
This was the fourth close flyby since Juno began orbiting Jupiter last year on July 4. During these close passes instruments
 on the spacecraft probe beneath the cloud cover to collect scientific data about the planet's structure, atmosphere and magnetosphere.
 This information could help us better understand the planetary systems being discovered around other stars.
 Also, Cassini Sees Saturn’s Rings in Greater Detail, The Most Extreme Blazars, 
 NASA at Super Bowl Event, NASA at NBA Black Heritage Celebration, and Day of Remembrance!
Category
Science & Technology
License
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NASA JUNO: 3-D Flyover of Jupiter’s North Pole in Infrared

Jupiter: Into the Unknown (NASA Juno Mission Trailer)

The Juice Mission

Artist concept of JUICE, an ESA concept for a Jupiter-moons orbiter mission. Credit: ESA

Jupiter-Bound Spacecraft Takes A Small Step To Seek Habitable Worlds by ELIZABETH HOWELL on DECEMBER 1, 2014

Artist?s impression of the Jupiter Icy Moons Explorer (JUICE) near Jupiter and one of its moons, Europa. Credit: ESA/AOES

It takes years of painstaking work to get a spacecraft off the ground. So when you have a spacecraft like JUICE (the Jupiter Icy Moons Explorer)

 set to launch in 2022, you need to back up about a decade to get things figured out. How will the spacecraft get there? 

 What science instruments will it carry? What will the spacecraft look like and what systems will support its work?

SPACEX's Mission Proposal

SpaceX’s newly revealed Interplanetary Transit System will make travel to Mars, and other destinations in our Solar System, possible.
 Credit: SpaceX
 

More Frank R. Paul art this time showing the inhabitants of one of Jupiter's moons.
 This time it's weird penguin/chicken people.
 

An amazingly active Io, Jupiter’s “pizza moon” shows multiple volcanoes and 
hot spots in this photo taken with Juno’s infrared camera.
 Credit: NASA / JPL-Caltech / SwRI / ASI / INAF /JIRAM / Roman Tkachenko
 

Linda Morabito spotted the puzzling plume off Io’s limb in this photo, taken on March 8, 1979, 
three days after Voyager 1’s encounter with Jupiter. It really does look like another moon poking
 out from behind Io. A second plume over the terminator (border between day and night)
 catches the rays of the rising Sun. Credit: NASA / JPL
 

This map shows thermal emission from erupting volcanoes on Io. The larger the spot, 
the larger the thermal emission.
 Credit: NASA/JPL-Caltech/Bear Fight Institute
 

This five-frame sequence (Repeating Sequence on this video) of New Horizons images captures the giant plume 
from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI)
 as the spacecraft flew past Jupiter earlier this year, this first-ever "movie" of an Io plume 
 clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) 
 above the moon's surface. Only the upper part of the plume is visible from this vantage point
 -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.
The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, 
replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion
 are still mysterious, but this movie is likely to help scientists understand their origin, 
 as well as provide unique information on the plume dynamics.
Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible 
off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume,
 possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io,
 and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki,
 likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io 
 and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.
The five images were obtained over an 8-minute span, with two minutes between frames, 
from 23.50 to 23.58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) 
from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.
The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io
 in the sequence because the moon was passing behind Jupiter's rings at the time.
 

Jupiter’s Volcanic Moon Io by Matt Williams on October 21, 2015

Global view of Jupiter’s moon Io, obtained during the tenth orbit of Jupiter by NASA’s Galileo spacecraft. Credit: NASA
 

Enhanced-color Galileo image showing a dark spot produced by a major eruption at Pillan Patera in 1997. Credit: NASA/JPL
 

False-color mosaic of the surface of Io. Large mountains appear in dark grey and black. Credit: USGS Astrogeology Science Center
 

Model of the possible interior composition of Io with various features labelled. Credit: Wikipedia Commons/Kelvinsong
 

Io's Volcanoes are in the Wrong Place

          This five-frame sequence of images from NASA?s New Horizons mission captures the giant plume

           from Io?s Tvashtar volcano in March, 2007.

          Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.


Jupiter?s moon Io features at least 400 active volcanoes, making it the most volcanically active world in our Solar System.

 However, the location of the volcanoes on Io just doesn?t match up with scientific models that predict how the moon?s interior is heated.


?Rigorous statistical analysis of the distribution of volcanoes in the new global geologic map of Io,?

 said Christopher Hamilton of the University of Maryland, College Park and the Goddard Spaceflight Center. 

 ?We found a systematic eastward offset between observed and predicted volcano locations that can?t be reconciled

 with any existing solid body tidal heating models.? 

 

LTvashtar Paterae

 Uploaded on Apr 30, 2011
A plume erupts from the Io's Tvashtar volcanic area as the moon transits Jupiter.
 Io's own shadow is visible as a dark disk on the Jupiter's cloud tops. Filaments
 (from an as yet unexplained mechanism) are visible in the plume.
The appearance of Tvashtar's plume was based on this composite of images from the
 New Horizons spacecraft: 

Rendered in real time using the VESTA engine.

    Category
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The Electrical "Volcanoes" of Jupiter's Moon Io | Space News

 Published on Apr 25, 2013

The so-called "volcanoes" on Jupiter's moon Io have long been conventionally interpreted as the effect of tidal forces acting on the moon.

 But a recent scientific paper has announced that this longstanding explanation does not fit with the actual location of the plumes.

 Is it possible that this failure of theory could cause planetary scientists to reconsider the electrical explanation first offered by

 astrophysicist Thomas Gold and later by plasma scientists Anthony Peratt and Alex Dessler?


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Pictures of Io’s auroral activity, captured by the Galileo spacecraft on October 16, 1998. Credit: NASA/JPL/University Of Arizona (PIRL)
 

Mosaic of Voyager 1 images of Io’s south polar region, which includes two of Io’s ten highest peaks –

 Euboea Montes (upper right) and Haemus Mons (left). Credit: NASA/JPL/USGS
 

Time-lapse sequence of clear-filter images of Io during the eclipse of January 1, 2001.

Credit: NASA/JPL/USGS
 

Lava Lake Loki on Jupiter's moon Io, up close
Date: May 1, 2015
Source:University of Arizona

 The LBT image of Loki Patera (orange) laid over a Voyager image of the volcanic depression. 

 The emission (in orange color) appears spread out in the north-south direction due to the telescope point-spread function;

 it is mainly localized to the southern corners of the lake.

Credit: LBTO- NASA

 

The Interior of IO

 Of Jupiter?s four large Galilean satellites, Io is the closest to the planet.

 It?s about the same size as Europa and the Earth?s Moon. It may be the strangest satellite humans have ever studied.

 Voyager photos of Io revealed erupting volcanoes. This wasn?t too surprising, because Jupiter?s intense tidal forces heat 

 the interior of the satellite, just like on Europa. But subsequent observations show that volcanoes are always erupting 

 on Io - in fact, it?s the most volcanically active world in the solar system! Material shot up by the many volcanoes

 rises high above the surface of the little satellite and then falls back in a lazy arc due to Io?s weak gravity.

 Volcanic activity adds about 10 centimeters of new material to the surface each year.

 

Animation of IO's transit of Jupiter

A Dec. 24, 2014 (EST) timelapse of Io transiting Jupiter. Credit: IKYLSP/Reddit

On Christmas Eve, as millions upon millions of people focused on wrapping gifts and getting ready for the holidays,

an amateur astronomer gave a small gift to the world. The person turned a telescope and camera to Jupiter and caught volcanic

Io going across the face of the gas giant. This happened just a few days after professional astronomers caught a rare eclipse 

involving that very same moon.

Jupiter's Moon: Io Rotation - HD Kurdistan Planetarium Kurdistan Planetarium

Published on Apr 26, 2012
Io is the innermost of the four Galilean moons of Jupiter and, with a diameter of 3,642 kilometers, the fourth-largest moon in the Solar System. 

It was named after Io, a priestess of Hera who became one of the lovers of Zeus. Nevertheless, it was simply referred to as Jupiter I, or 

The first satellite of Jupiter, until mid-20th century.

With over 400 active volcanoes, Io is the most geologically active object in the Solar System. Its surface is dotted with more than 100 mountains,

some which are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System (which have a thick coating of ice),

Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core.
Although not proven, recent data from the Galileo orbiter indicates that Io might have its own magnetic field Io has an extremely 

thin atmosphere made up mostly of sulfur dioxide (SO2). If a surface data or collection vessel were to land on Io in the future,

 it would have to be extremely tough (similar to the tank-like bodies of the Soviet Venera landers) to survive the radiation and magnetic fields 

 that originate from 

Discovered by Galileo Galilei 
Discovery date January 7, 1610 
Designations 
Alternate name Jupiter I 
Adjective Ionian 
Orbital characteristics 
Periapsis 420,000 km (0.002 807 AU) 
Apoapsis 423,400 km (0.002 830 AU) 
Mean orbit radius 421,700 km (0.002 819 AU) 
Eccentricity 0.0041 
Orbital period 1.769 137 786 d (42 h) 
Average orbital speed 17.334 km/s 
Inclination 2.21° (to the ecliptic)
0.05° (to Jupiter's equator) 
Satellite of Jupiter 
Physical characteristics 
Dimensions 3,660.0 × 3,637.4 × 3,630.6 km
Mean radius 1,821.3 km (0.286 Earths)[1] 
Surface area 41,910,000 km2 (0.082 Earths) 
Volume 2.53 × 1010 km3 (0.023 Earths) 
Mass 8.9319 × 1022 kg (0.015 Earths) 
Mean density 3.528 g/cm3 
Equatorial surface gravity 1.796 m/s2 (0.183 g) 
Escape velocity 2.558 km/s 
Rotation period synchronous 
Equatorial rotation velocity 271 km/h 
Albedo 0.63 ± 0.02 
Surface temp.
Surface min mean max 
130 K 200 K 

Apparent magnitude 5.02 (opposition)
Atmosphere 
Surface pressure trace 
Composition 90% sulfur dioxide
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Published on Apr 25, 2013
The so-called "volcanoes" on Jupiter's moon Io have long been conventionally interpreted 

as the effect of tidal forces acting on the moon. But a recent scientific paper has announced 

that this longstanding explanation does not fit with the actual location of the plumes.

 Is it possible that this failure of theory could cause planetary scientists to reconsider 

 the electrical explanation first offered by astrophysicist Thomas Gold and later by plasma scientists Anthony Peratt and Alex Dessler?

Subscribe to Thunderbolts Update weekly newsletter: http://eepurl.com/ETy41
Thunderbolts Project Home: http://www.thunderbolts.info
Facebook: http://www.facebook.com/thunderboltsp...
Picture of the Day: http://www.thunderbolts.info/wp/daily...
Electric Universe (Wal Thornhill): http://www.holoscience.com/wp/
Essential Guide to the Electric Universe: http://www.thunderbolts.info/wp/eg-co...
Category
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License
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Infrared image of the southern hemisphere of Jupiter’s moon Io taken by NASA's Juno spacecraft on Dec. 16, 2017.
 Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

Annotated image of the new heat source close to the south pole of Io,
 with a scale depicting the range of temperatures displayed in the infrared image.
 Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

Thanks to a mission extension, NASA’s Juno probe continues to orbit Jupiter, 
being only the second spacecraft in history to do so. Since it arrived around the gas giant on July 5th, 2016,
 Juno has managed to gather a great deal of information on Jupiter’s atmosphere,
 magnetic and gravity environment, and its interior structure.

Reconstructed image acquired by the JunoCam at 12:20 (UTC) on Dec. 21, 2018.
 Credit: NASA/SwRI/MSSS

Image captured by Juno’s Stellar Reference Unit (SRU) camera shortly 
after Io was eclipsed by Jupiter at 12:40:29 (UTC) Dec. 21, 2018.
 Credit: NASA/JPL-Caltech/SwRI

Image acquired by the Jovian Infrared Auroral Mapper (JIRAM) at 12:30 (UTC) on Dec. 21st, 2018.
 Credit: NASA/JPL-Caltech/SwRI/INAF

Jupiter's Moon Europa

These signals were recorded by the Voyager 1 plasma wave instrument as the spacecraft flew past Jupiter on March 5, 1979. 
 Jovian whistler waves propagate at audio frequencies along closed field lines in Jupiter's magnetosphere.
 Like Earth whistlers, the higher frequency components of the Jovian whistler propagate faster than the lower frequency 
 components, resulting in a descending whistling tone. Also like Earth whistlers, Jovian whistlers are 
 generated by lightning discharges in the atmosphere. It was the detection of these signals that provided 
 the first indirect evidence of lightning on the giant planet.
The video shows a spectrogram with time along the horizontal axis, frequency on the vertical axis,
 and color-coded amplitude with weak signals blue and strong signals red.  A moving cursor shows the time 
 of the corresponding audio.

For more information on the Voyager project:

This is a sample 
from the collection of Prof Don Gurnett's favorite space audio recordings available from:


For similar videos:

A low flyover of Jupiter's moon Europa using recently processed data from NASA's Galileo orbiter.
 Uses high resolution grayscale and low resolution color images taken between 1996 and 1998. 
Credit:
NASA/JPL-Caltech/Kevin M. Gill

Music: Kevin MacLeod via YouTube.

Image: These composite images show a suspected plume of material erupting two years apart from the same location on Jupiter’s icy moon Europa.
 The newly imaged plume, shown at right, rises about 100 kilometers above Europa’s frozen surface. The image was taken Feb. 22, 2016. 
 The plume in the image at left, observed by Hubble on March 17, 2014, originates from the same location.
 It is estimated to be about 50 kilometers high. The snapshot of Europa, superimposed on the Hubble image, was assembled from data 
 from NASA’s Galileo mission to Jupiter.
 Credit: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center.

This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 26, 2014.

 Credit: Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center

Image: These images of the surface of the Jovian moon Europa, taken by NASA’s Galileo spacecraft,
 focus on a “region of interest” on the icy moon. The image at left traces the location of the erupting plumes of material,
 observed by NASA’s Hubble Space Telescope in 2014 and again in 2016. The plumes are located inside the area surrounded by the green oval.
 The green oval also corresponds to a warm region on Europa’s surface, as identified by the temperature map at right.
 The map is based on observations by the Galileo spacecraft. The warmest area is colored bright red.
 Credit: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center.

NASA's Report on a mission to Europa.

NASA's Report on the Their Mission to Europa

This image shows two views of the trailing hemisphere of Jupiter's ice-covered satellite, Europa.

The left image shows the approximate natural color appearance of Europa. The image on the right is a false-color

composite version combining violet, green and infrared images to enhance color differences in the predominantly water-ice crust of Europa.

 This image was taken in 1996, at a range of 677,000 kilometers (417,900 miles) by the solid state imaging television camera 

 onboard the Galileo spacecraft during its second orbit around Jupiter.

 

P>

Europa REMASTERED!!!

 NASA?s ?Remastered? View of Europa is the Best Yet by MATT WILLIAMS on NOVEMBER 21, 2014 Europa.

The cracked, icy surface of Europa. The smoothness of the surface has led many scientists to conclude that oceans exist beneath it.

 Credit: NASA/JPLredit: NASA

 

The Lure of Europa - Featuring Bill Nye and special guests

Published on Aug 4, 2014
Europa is a moon of Jupiter that may have three crucial ingredients for life: liquid water, energy, and nutrients. What,

 if anything, can be found in the great oceans of Europa? Could NASA look for life? How could we explore affordably?

 Bill Nye The Science Guy, eminent NASA scientists, and prominent legislators examined just these questions in a public event 

 inside the halls of Congress. This was recorded live on July 15th, 2014.


Recorded by Tushar Dayal.

Speakers (in order of appearance):
* Casey Dreier (Director of Advocacy for The Planetary Society and event emcee)
* Rep. Lamar Smith (Chairman, House Science Committee; Texas 21st District)
* Rep. John Culberson (Texas 7th District)
* Rep. Adam Schiff (California 21st District)
* Dr. Ellen Stofan (Chief Scientist, NASA)
* Dr. Robert Pappalardo (Europa Study Scientist, JPL)
* Bill Nye, The Science Guy (CEO of The Planetary Society)

Europa: Ocean World

Published on Nov 21, 2014

Scientists believe there is an ocean hidden beneath the surface of Jupiter's moon Europa. 

NASA-JPL astrobiologist Kevin Hand explains why scientists are so excited about the potential of this ice-covered world 

to answer one of humanity's most profound questions

Published on Nov 13, 2015
Could life exist on Europa? It may sound farfetched, but this Jovian moon is the most likely place to find life 

in our solar system thanks to an enormous underground ocean positioned just beneath its icy surface.

Watch as Robert Pappalardo, Europa Project Scientist at NASA Jet Propulsion Laboratory, discusses Europa,

 its potential for life, and the upcoming mission that is being planned to visit this compelling moon.

This video was developed from a live recording at the AIAA SPACE 2015 conference in September 2015.

 To watch the full talk given at the conference click here
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Screenshot by Michelle Starr/CNET

When it comes to life, biologists have long hypothesised that its origins -- on Earth, 

at least -- were in thermal vents on the ocean floor, following a period of spontaneous metabolism before life began.

 Thermal vents are rich sites for marine life -- especially in Antarctica where, in the darkness under the ice,

 creatures proliferate in the warm, mineral-rich waters streaming from the vents.

 It's just one of several theories, but if it's correct, Jupiter's moon Europa could be a very exciting place indeed.

 Ever since plumes of vapour were discovered on Jupiter's moon in December last year, NASA has been floating theories about

 the oceans that may be sloshing away under the layer of surface ice -- its similarities to theories about the early Earth

 look like it may have the ingredients for life.

This reprojection of the official USGS basemap of Jupiter's moon Europa is centered at the estimated source region for potential water vapor plumes that might have been detected using the Hubble Space Telescope. The view is centered at -65 degrees latitude, 183 degrees longitude.

In addition to the plume source region, the image also shows the hemisphere of Europa that might be affected by plume deposits. This map is composed of images from NASA's Galileo and Voyager missions. The black region near the south pole results from gaps in imaging coverage.
Image Credit: NASA/JPL-Caltech/SETI Institute

Last Updated: May 29, 2015
Editor: Sarah Loff

NASA Gives ‘GO’ for Mission to Alien Ocean World at Jupiter Moon Europa
by KEN KREMER on JUNE 18, 2015

Artist’s concept of NASA mission streaking over ocean world of Europa. Credit: NASA/JPL

JA false color image shows Europa’s surprising surface. The inset includes regions where crustal plates appear to have broken up

 and rafted to new positions.
NASA/JPL -  See more
Europa’s heaving ice might make more heat than scientists thought
Apr 15, 2016
A new set of experiments sheds light on how much heat is created when ice is deformed,

 which could help scientists understand the possibility of a subsurface ocean on one of Jupiter’s moons
Europa’s heaving ice might make more heat than scientists thought
Apr 15, 2016
A new set of experiments sheds light on how much heat is created when ice is deformed,

 which could help scientists understand the possibility of a subsurface ocean on one of Jupiter’s moons.

Jupiter’s moon Europa is under a constant gravitational assault. As it orbits, Europa’s icy surface heaves 

and falls with the pull of Jupiter’s gravity, creating enough heat, scientists think,

 to support a global ocean beneath the moon’s solid shell.

Hubble’s Surprising Find On Europa To Be Announced By NASA Monday September 26, 2016

Published: 21 Sep , 2016
by Evan Gough

NASA will make a “surprising” announcement about Jupiter’s moon Europa on Monday, Sept. 26th, at 2:00 PM EDT.

 They haven’t said much, other than there is “surprising evidence of activity that may be related to the 

 presence of a subsurface ocean on Europa.” Europa is a prime target for the search for life because of its subsurface ocean.

Images from NASA’s Galileo spacecraft show the intricate detail of Europa’s icy surface.

 Image: NASA/JPL-Caltech/ SETI Institute

What About A Mission To Europa? 

Published on Jul 27, 2015

Europa’s water exists in a layer around the planet, encased in a layer of ice. Could there be life down there?
 Support us at:
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Team: Fraser Cain - @fcain
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Created by: Fraser Cain and Jason Harmer

This artist’s illustration shows what plumes of water vapour might look like being ejected from Europa’s south pole.

 Image: NASA, ESA, L. Roth (Southwest Research Institute, USA/University of Cologne, Germany) and M. Kornmesser.

Two models of the interior of Europa. Image: NASA/JPL.

More About Europa:

    The Search For Life On Europa Could Center On Celestial Party-Crashers
    A New Image of Europa Emerges
    Icy Hot: Europa’s Frozen Crust Could Be Warmer Than We Thought

Hubble may have caught jets of water squirting out of a potentially habitable moon
Dave Mosher,Business Insider

A plume of subsurface ocean water vapor escapes through a crack in the icy crust of Europa, a moon of Jupiter
CREDIR:.NASA/ESA/K. Retherford/SWRI) 
Jupiter's moon Europa — a giant ice ball thought to hide twice as much liquid water as there is on Earth —

 just became an even hotter target in the search for aliens.
Scientists on Monday unveiled new photographs from NASA's Hubble Space Telescope, and they likely show "fingers"

 of water vapor squirting out of Europa's hidden ocean and into space.

(Suspected plumes of water vapor spouting out of Jupiter's moon Europa.Hubble/NASA/STScI/Business Insider) 
Those blotchy "dark fingers," circled in red, are the suspected plumes.

During a press teleconference on Monday, William Sparks, an astronomer at the Space Telescope Science Institute, said 

"we are really working at the limits of Hubble's unique capabilities."
"Trying to just image Europa with the Hubble Space Telescope clearly from Earth is challenging," Pappalardo said. 

"Trying to image the [silhouette] of a plume, via the light of Jupiter, is a remarkably hard feat.

 There's essentially a lot of noise in the system."
NASA's press materials lean heavily on the word "if" as well (our emphasis added):
"These plumes, if they do indeed exist, may provide another way to sample Europa's subsurface," 

Geoff Yoder, the associate administrator for NASA's Science Mission Directorate, said in the space agency's release.
Another "if" regarded the moon's water-enriched atmosphere: "If there is a thin atmosphere around Europa,

 it has the potential to block some of the light of Jupiter, and we could see it as a silhouette," Sparks said in the release.

The next mission to Europa

(This artist's rendering shows a concept for a future NASA mission to Europa in which a spacecraft would make multiple close flybys of the icy Jovian moon,

 thought to contain a global subsurface ocean.NASA/JPL-Caltech) 

Animation - Plumes on Europa

Uploaded on Sep 26, 2016
Artist’s concept: Astronomers using NASA's Hubble Space Telescope have imaged what may be water vapor plumes erupting off the surface of Jupiter's moon Europa. If the plumes, indeed, emerge and rain down on the surface, it may be much easier to access material that was once in the ocean of Europa.
 News release:
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Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter,

 raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. 

 Credits: A. Field (STScI)

EUROPA LANDER COULD CARRY A MICROPHONE AND “LISTEN” TO THE ICE TO FIND OUT WHAT’S UNDERNEATH

Artist's rendering of a possible Europa Lander mission, which would explore the surface of the icy moon in the coming decades. 
Credit:: NASA/JPL-Caltech

Image of Europa’s ice shell, taken by the Galileo spacecraft, of fractured “chaos terrain”. 
Credit: NASA/JPL-Caltech

Europa’s “Great Lake.” Scientists speculate many more exist throughout the shallow regions of the moon’s icy shell.
 Credit: Britney Schmidt/Dead Pixel FX/Univ. of Texas at Austin.

Artist’s concept of chloride salts bubbling up from Europa’s liquid ocean and reaching the frozen surface. 
 Credit: NASA/JPL-Caltech

This animation demonstrates how deformation in the icy surface of Europa could transport subsurface ocean water
 to the moon’s surface.
This is just one of several simulated behaviors reported in a new study performed by scientists at
 NASA’s Jet Propulsion Laboratory. The study focused on linear features called “bands” and “groove lanes”
 found on Jupiter’s moons Europa and Ganymede. Scientists have used the same numerical model to solve mysteries
 about motion in Earth’s crust.
The animation is a two-dimensional simulation of a possible cross-section of a band running through Europa’s ice shell.
 At the extreme bottom is Europa’s ocean, and the thick white line across the top represents the moon’s surface ice.
 The midsection is the bulk of Europa’s ice shell, with warmer colors (red, orange, yellow) representing stronger, 
 more rigid ice. Depth is marked on the left side of the animation while numbers on the bottom measure distance 
 from the center of the band feature on Europa’s surface. Bands on Europa and Ganymede are typically tens of miles wide
 and hundreds of miles long. Numbers at the top mark the passage of time in thousands of years.
As the animation runs forward, the ice shell is deformed by gravitational interactions with Jupiter. 
The cold, brittle ice at the surface gets pulled apart. At the same time, faults in the upper ice form,
 heal, and re-form (visible as diagonal yellow, green and blue lines in the upper center of the animation).
 The churning material that quickly fills the bottom half of the view is a collection of tiny white dots
 representing bits of Europa’s ocean that have been frozen into the bottom of Europa’s ice shell 
 (i.e. where the liquid ocean is in contact with the frozen shell).
In the paper, the scientists describe it as “fossil” ocean material because the bits of ocean trapped in 
Europa’s ice shell spend many hundreds of thousands, if not millions, of years being carried to the surface. 
In other words, by the time the ocean material reaches Europa’s surface where it can be analyzed by a passing spacecraft,
 it no longer serves as a sample of Europa’s ocean as it is in the present. Instead, the spacecraft would actually
 be studying Europa’s ocean as it was a million or more years ago. Hence, it is fossil ocean material.
NASA’s Europa Clipper spacecraft is intended to launch in the early 2020s. The spacecraft will then orbit Jupiter 
and become the first spacecraft to study Europa exclusively, including the composition of the moon’s surface material.
 The mission will likely be able to test the model simulated above by using ice-penetrating radar to probe the moon’s
 bands. If Europa indeed behaves the way the simulation suggests, it might carry ocean material to the moon’s surface, 
 where Europa Clipper would analyze it remotely using the spacecraft’s infrared and ultraviolet instruments,
 among others. Scientists could then study the material’s composition to consider whether Europa’s ocean 
 might be hospitable for some form of life.

Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-6215
gretchen.p.mccartney@jpl.nasa.gov

animation credits:
 NASA/JPL-Caltech/Samuel M. Howell

Images from NASA’s Galileo spacecraft show the intricate detail of Europa’s icy surface. 
Image: NASA/JPL-Caltech

Based on new evidence from Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up
 from the icy moon's global liquid ocean and reach the frozen surface where they are bombarded
 with sulfur from volcanoes on Jupiter's innermost large moon Io. The new findings propose answers to questions
 that have been debated since the days of NASA's Voyager and Galileo missions. This illustration of Europa (foreground),
 Jupiter (right) and Io (middle) is an artist's concept.
 Credit: NASA/JPL-Caltech

LIFE ON EUROPA WOULD BE PROTECTED BY JUST A FEW CENTIMETERS OF ICE

Radiation from Jupiter can destroy molecules on Europa's surface. Material from Europa's ocean 
that ends up on the surface will be bombarded by radiation, possibly destroying any biosignatures,
 or chemical signs that could imply the presence of life.
 Credit: NASA/JPL-Caltech

Artist’s concept of chloride salts bubbling up from Europa’s liquid ocean and reaching the frozen surface. 
 Credit: NASA/JPL-Caltech

Artist’s concept of a Europa Clipper mission. Credit: NASA/JPL

A plume of subsurface ocean water vapor escapes through a crack in the icy crust of Europa, a moon of Jupiter
CREDIR:.NASA/ESA/K. Retherford/SWRI) 
Jupiter's moon Europa — a giant ice ball thought to hide twice as much liquid water as there is on Earth —

 just became an even hotter target in the search for aliens.
Scientists on Monday unveiled new photographs from NASA's Hubble Space Telescope, and they likely show "fingers"

 of water vapor squirting out of Europa's hidden ocean and into space.

The search for life has led astronomers to the icy moons in our Solar System.
 Among those moons, Europa has attracted a lot of attention. Europa is Jupiter’s 
 fourth-largest moon—and the sixth-largest in the Solar System—at 3,100 kilometres (1,900 mi)
 in diameter. Scientists think that its oceans could contain two or three times as much water
 as Earth’s oceans. The only problem is, that water is hidden under a sheet of planet-wide ice 
 that could be between 2km and 30km (1.2 miles and 18.6 miles) thick.

Two models of the interior of Europa. A tunneling robot would be able to tunnel
 through the ice and search for life.
 Image: NASA/JPL.

Reprocessed Galileo image of Europa’s frozen surface 
by Ted Stryk (NASA/JPL/Ted Stryk)

Images from NASA’s Galileo spacecraft show the intricate detail of Europa’s icy surface.
 A tunnelling robot would be just the vehicle to explore the oceans under the ice.
 Image: NASA/JPL-Caltech/ SETI Institute

Image of Europa’s ice shell, taken by the Galileo spacecraft, of fractured “chaos terrain.”
 A tunneling robot would likely be sent to this type of surface area. 
 Image Credit: NASA/JPL-Caltech

Russia's Proposed Mission to Ganymede in russian!

Ганимед: на пороге открытий

Published on Jul 29, 2016
В НПО имени Лавочкина, где создавались все отечественные межпланетные станции, а сейчас строятся аппараты 

лунной программы и орбитальные обсерватории серии «Спектр», прорабатывается проект «Лаплас». Это два аппарата,

 которые в ближайшее десятилетие планируют отправить к Юпитеру. Цель исследований - спутник Юпитера – Ганимед.

 Еще один объект изучения – Меркурий. Планета входит в т.н. «земную группу планет», но знания землян о нем – самые общие.

 Этот пробел должна восполнить миссия «БепиКоломбо». В проекте принимают участие ЕКА, Роскосмос и JAXA. 

 На аппарате, который отправится к самой маленькой планете Солнечной системы через два года, будет установлен

 российский прибор для поиска воды.
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Jupiter's Great Red Spot and Ganymede?s Shadow.(Ganymede the largest moon in the solar system) Image Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)

Halloween is just around the corner. And in what appears to be an act of cosmic convergence, Hubble captured a spooky image of Jupiter

staring back at us with a cyclops eye!

While this is merely a convenient illusion caused by the passage of Ganymede in front of Jupiter ?

 something it does on a regular basis ? the timing and appearance are perfect.

Ganymede?s Subsurface Ocean is Like a Club Sandwich by Nancy Atkinson on May 1, 2014 Read more: www.universetoday...

This image of Ganymede, one of Jupiter's moons and the largest moon in our solar system was taken by NASA's Galileo spacecraft.
Image Credit: NASA

This image of Ganymede, one of Jupiter's moons and the largest moon in our solar system was taken by NASA's Galileo spacecraft.
Image Credit: NASA

Many people think that the answer to ‘what is the largest moon in the Solar System’ is our Moon.

It is not. Our Moon is the fifth largest natural satellite. Ganymede, a moon of Jupiter, is the largest in this solar system.

 At 5,268 km at the equator
Image Credit: NASA

Montage showing New Horizons’ views of Ganymede taken by it’s infrared spectrometer and LORRI and LEISA instruments.

 Credit: NASA/Johns Hopkins University APL/SwRI

Artist’s concept for a future settlement on Ganymede. Credit: futuretimeline.net

Artist’s concept of the Jupiter Icy Moons Orbiter (JIMO), a cancelled program 

that envisioned sending a spacecraft to inspect Callisto,

Ganymede and Europa. Credit: NASA/JPL

Uploaded on Jan 6, 2010
Callisto (pronounced /kəˈlɪstoʊ/,or as Greek Καλλιστώ) is a moon of the planet Jupiter, discovered in 1610 by Galileo Galilei.

It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede.

 Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass. It is the fourth Galilean moon of Jupiter by distance,

 with an orbital radius of about 1 880 000 km. It does not form part of the orbital resonance that affects three inner Galilean satellites—Io, Europa and Ganymede—

 and thus does not experience appreciable tidal heating. Callisto rotates synchronously with its orbital period, so the same face is always turned toward Jupiter.

 Callisto's surface is less affected by Jupiter's magnetosphere than the other inner satellites because it orbits farther away.

Callisto is composed of approximately equal amounts of rock and ices, with a mean density of about 1.83 g/cm3. Compounds detected

spectrally on the surface include water ice, carbon dioxide, silicates, and organic compounds. Investigation by the Galileo spacecraft 

revealed that Callisto may have a small silicate core and possibly a subsurface ocean of liquid water at depths greater than 100 km.

The surface of Callisto is heavily cratered and extremely old. It does not show any signatures of subsurface processes such as plate tectonics,

earthquakes or volcanoes, and is thought to have evolved predominantly under the influence of impacts. Prominent surface features include multi-ring structures,

variously shaped impact craters, and chains of craters (catenae) and associated scarps, ridges and deposits. At a small scale, the surface is varied and consists of small,

 bright frost deposits at the tops of elevations, surrounded by a low-lying, smooth blanket of dark material. This is thought to result from the sublimation-driven degradation 

 of small landforms, which is supported by the general deficit of small impact craters and the presence of numerous small knobs, considered to be their remnants.The absolute ages

 of the landforms are not known.
Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide[6] and probably molecular oxygen, as well as by a rather intense ionosphere. Callisto is thought 

to have formed by slow accretion from the disk of the gas and dust that surrounded Jupiter after its formation. Its slowness and the lack of tidal heating prevented rapid differentiation.

 The slow convection in the interior of Callisto, which commenced soon after formation, led to partial differentiation and possibly to the formation of a subsurface ocean at a depth of 100150 km and a small, rocky core.

The likely presence of an ocean within Callisto indicates that it can or could harbor life. However, this is less likely than on nearby Europa. Various space probes from Pioneers 10 and 11 to Galileo and Cassini have studied the moon.

 Callisto has long been considered the most suitable place for a human base for future exploration of the system of Jupiter.

Discovered by G. Galilei
S. Marius
Discovery date January 7, 1610
Designations 
Alternate name Jupiter IV 
Adjective Callistoan, Callistian 
Orbital characteristics 
Periapsis 1 869 000 km[b] 
Apoapsis 1 897 000 km[a] 
Mean orbit radius 1 882 700 km
Eccentricity 0.007 4 
Orbital period 16.689 018 4 d
Average orbital speed 8.204 km/s 
Inclination 0.192° (to local Laplace planes)
Satellite of Jupiter 
Physical characteristics 
Mean radius 2410.3 ± 1.5 km (0.378 Earths) 
Surface area 7.30 × 107 km2 (0.143 Earths) 
Volume 5.9 × 1010 km3 (0.0541 Earths)
Mass 1.075 938 ± 0.000 137 × 1023 kg (0.018 Earths)
Mean density 1.834 4 ± 0.003 4 g/cm3[3] 
Equatorial surface gravity 1.235 m/s2 (0.126 g) 
Escape velocity 2.440 km/s
Rotation period synchronous
Axial tilt zero 
Albedo 0.22 (geometric)
Surface temp.
K[4] min mean max 
80 ± 5 134 ± 11 165 ± 5 

Apparent magnitude 5.65 (opposition)
Atmosphere 
Surface pressure 7.5 pbar 
Composition ~4 × 108 cm−3 carbon dioxide
up to 2 × 1010 cm−3 molecular oxygen
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Model of Callisto’s internal structure showing a surface ice layer, a possible liquid water layer, and an ice–rock interior.

 Credit: NASA/JPL

Interior density structures created by an outer solar system late heavy bombardment onto Ganymede (top row) and Callisto (bottom row).

 Credit: SwRI

Voyager 1 image of Valhalla, a multi-ring impact structure 3800 km in diameter. Credit: NASA/JPL

New Horizons Long Range Reconnaissance Imager (LORRI) captured these two images of Jupiter’s outermost large moon, Callisto,

 during its flyby in February 2007. Credit: NASA/JPL

Artist’s impression of a base on the icy surface of Callisto. Credit: NASA