EarthSky | See 1st new images of Ganymede in over 20 years

New images of Ganymede, moon-like body with rayed crater and bright and dark patches.
View larger. | Wow! Beautiful new view of Jupiter’s largest moon Ganymede, from the flyby on June 7, 2021. Picture through NASA/ JPL/ SwRI/ MSSS/ Kevin Gill/ Twitter.

The final time we noticed Jupiter’s largest moon Ganymede up shut was over 20 years in the past. Now NASA has released new closeups of the moon, taken on June 7, 2021, by the Juno orbiter. The gorgeous pictures reveal Ganymede’s icy floor in putting element. They present the moon’s craters, vivid and darkish terrain and lengthy linear options which may be just like tectonic faults on Earth.

First flyby of Ganymede in over 20 years

That is the closest that any spacecraft has come to the enormous moon for the reason that Galileo spacecraft’s shut flyby on Might 20, 2000. Juno flew previous Ganymede on Monday, June 7, at 1:35 p.m. EDT (10:35 a.m. PDT). It got here inside 645 miles (1,038 km) of the floor at closest method. Scott Bolton of the Southwest Analysis Institute (SwRI) and Juno Principal Investigator mentioned in a statement:

That is the closest any spacecraft has come to this mammoth moon in a era. We’re going to take our time earlier than we draw any scientific conclusions, however till then we will merely marvel at this celestial surprise.

Moon-like body with craters, bright and dark patches, and lines.
One other nice view of Ganymede’s advanced floor. Picture through NASA/ JPL-Caltech/ SwRI/ MSSS.

New pictures of Ganymede and its icy floor

The pictures present our first good glimpse of this mysterious world in over 20 years. One picture was taken by Juno’s JunoCam imager and the opposite is from the Stellar Reference Unit (SRU) star digicam.

Juno was in a position to seize nearly a whole facet of Ganymede with JunoCam, with a decision of 0.6 miles (1 km) per pixel. Proper now many of the pictures are in black-and-white, however different pending images will probably be in colour.

The SRU digicam checked out Ganymede’s darkish facet, illuminated solely by dim daylight reflecting off Jupiter. The decision in that picture is 0.37 to 0.56 miles (600 to 900 meters) per pixel. In line with Heidi Becker, Juno’s radiation monitoring lead at JPL:

The circumstances wherein we collected the darkish facet picture of Ganymede have been excellent for a low-light digicam like our Stellar Reference Unit. So it is a completely different a part of the floor than seen by JunoCam in direct daylight. Will probably be enjoyable to see what the 2 groups can collectively.

Orangish moon-like body with craters and bright and dark patches.
View larger. | Shade-enhanced view of Ganymede. Picture through NASA/ JPL/ SwRI/ MSSS/ Gerald Eichstädt.
Closeup of gray moon-like surface with craters and long cracks.
A better view of Ganymede’s floor, exhibiting craters and lengthy linear options which may be tectonic in origin. Picture through NASA/ JPL-Caltech/ SwRI.

Juno, Jupiter and Ganymede

Juno’s main mission has been to review Jupiter itself, analyzing its clouds, storms, and deep inside. However the spacecraft can also be well-equipped to take a look at a few of its moons as effectively. As Bolton defined:

Juno carries a set of delicate devices able to seeing Ganymede in methods by no means earlier than potential. By flying so shut, we’ll convey the exploration of Ganymede into the 21st century, each complementing future missions with our distinctive sensors and serving to together for the following era of missions to the Jovian system: NASA’s Europa Clipper and ESA’s [European Space Agency’s] JUpiter ICy moons Explorer [JUICE] mission.

The probe additionally used different devices to review Ganymede, together with the Ultraviolet Spectrograph (UVS) and Jovian Infrared Auroral Mapper (JIRAM). The Radiometer (MWR) instrument may higher decide the composition and temperature of Ganymede’s water-ice crust.

Man talking into microphone with his name on board in front of him.
Scott Bolton on the Southwest Analysis Institute (SwRI) is the Principal Investigator of the Juno mission. Picture through TechCrunch.

Largest moon within the photo voltaic system

Ganymede will not be solely Jupiter’s largest moon, it’s the largest pure satellite tv for pc in the complete photo voltaic system. It’s even bigger than the planet Mercury. It’s also the one moon to have its personal magnetosphere. A magnetosphere is a bubble-shaped area of charged particle round a physique resembling a planet or moon.

Like Jupiter’s different giant moons Callisto and Europa, Ganymede has an icy floor and outer ice shell. That floor options craters, uncommon gentle and darkish areas and lengthy cracks just like tectonic faults on Earth. These are proof of lively geology on the moon previously, and maybe nonetheless on-going. Bolton mentioned:

Ganymede’s ice shell has some gentle and darkish areas, suggesting that some areas could also be pure ice whereas different areas comprise soiled ice. MWR will present the primary in-depth investigation of how the composition and construction of the ice varies with depth, resulting in a greater understanding of how the ice shell types and the continuing processes that resurface the ice over time.

An ocean on Ganymede?

Ganymede has three foremost layers: a metallic iron core, a rocky mantle and an outer shell of ice about 500 miles (800 km) thick. In 2015, NASA’s Hubble Space Telescope additionally discovered proof for a subsurface ocean of water on Ganymede. The ocean, beneath the ice crust, is estimated to be 60 miles (100 kilometers) deep, 10 occasions deeper than Earth’s oceans. John Grunsfeld, former affiliate administrator of NASA’s Science Mission Directorate, mentioned:

This discovery marks a milestone, highlighting what solely Hubble can accomplish. In its 25 years , Hubble has made many scientific discoveries in our personal photo voltaic system. A deep ocean underneath the icy crust of Ganymede opens up additional thrilling potentialities for all times past Earth.


If confirmed, Ganymede’s ocean could be considered one of a number of now identified to exist on icy moons within the outer photo voltaic system. Europa and Enceladus are the 2 most well-known of those worlds. Might it’s liveable? Nobody is aware of but, till extra information is obtained.

Juno will ship again extra pictures from the flyby over the approaching days, so keep tuned! Raw images can be found on the JunoCam web site.

The spacecraft has been orbiting Jupiter since 2016, finding out the enormous planet’s deep ambiance, clouds, storms, auroras and hidden inside. It additionally beforehand captured some stunning pictures of lively on the moon Io.

Backside line: NASA’s Juno spacecraft has despatched again the primary new closeup pictures of Jupiter’s largest moon Ganymede in over 20 years.



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