Mar 16, 2021
NASA’s Juno Reveals Dark Origins of One of Jupiter’s Grand Light Shows
This illustration depicts ultraviolet polar aurorae on Jupiter and Earth. While the diameter of the Jovian world is 10 times larger than that of Earth, both planets have markedly similar aurora.Credits: NASA/JPL-Caltech/SwRI/UVS/STScI/MODIS/WIC/IMAGE/ULiège
The gas-giant orbiter is illuminating the provenance of Jovian polar light shows.
New results from the Ultraviolet Spectrograph instrument on NASA’s Juno mission reveal for the first time the birth of auroral dawn storms – the early morning brightening unique to Jupiter’s spectacular aurorae. These immense, transient displays of light occur at both Jovian poles and had previously been observed only by ground-based and Earth-orbiting observatories, notably NASA’s Hubble Space Telescope. Results of this study were published March 16 in the journal AGU Advances.
First discovered by Hubble’s Faint Object Camera in 1994, dawn storms consist of short-lived but intense brightening and broadening of Jupiter’s main auroral oval – an oblong curtain of light that surrounds both poles – near where the atmosphere emerges from darkness in the early morning region. Before Juno, observations of Jovian ultraviolet aurora had offered only side views, hiding everything happening on the nightside of the planet.
“Observing Jupiter’s aurora from Earth does not allow you to see beyond the limb, into the nightside of Jupiter’s poles. Explorations by other spacecraft – Voyager, Galileo, Cassini – happened from relatively large distances and did not fly over the poles, so they could not see the complete picture,” said Bertrand Bonfond, a researcher from the University of Liège in Belgium and lead author of the study. “That’s why the Juno data is a real game changer, allowing us a better understanding what is happening on the nightside, where the dawn storms are born.”
Researchers found dawn storms are born on the nightside of the gas giant. As the planet rotates, the soon-to-be dawn storm rotates with it into the dayside, where these complex and intensely bright auroral features grow even more luminous, emitting anywhere from hundreds to thousands of gigawatts of ultraviolet light into space. The jump in brightness implies that dawn storms are dumping at least 10 times more energy into Jupiter’s upper atmosphere than typical aurora.
“When we looked at the whole dawn storm sequence, we couldn’t help but notice that they are very similar to a type of terrestrial auroras called substorms,” said Zhonghua Yao, co-author of the study at the University of Liège.”
Substorms result from brief disturbances in the Earth’s magnetosphere – the region of space controlled by the planet’s magnetic field – that release energy high into the planet’s ionosphere. The similarity between terrestrial and Jovian substorms is surprising because the magnetospheres of Jupiter and Earth are radically different. On Earth, the magnetosphere is essentially controlled by the interaction of the solar wind – the stream of charged particles flowing from the Sun – with Earth’s magnetic field. Jupiter’s magnetosphere is mostly populated by particles escaping from the volcanic moon Io, which then get ionized and trapped around the gas giant via its magnetic field.
These new findings will allow scientists to further study the differences and similarities driving the formation of aurora, providing a better understanding how these most beautiful of planetary phenomena occur on worlds both within our solar system and beyond.
“The power that Jupiter possesses is amazing. The energy in these dawn aurorae is yet another example of how powerful this giant planet really is,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “The dawn storm revelations are another surprise from the Juno mission, which is constantly rewriting the book on how giant planet’s work. With NASA’s recent mission extension, we’re looking forward to many more new insights and discoveries.”
More About the Mission
JPL, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott J. Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spacecraft.
More information about Juno is available at:
https://www.missionjuno.swri.edu
Follow the mission on Facebook and Twitter at:
https://www.facebook.com/NASASolarSystem
A major factor not mentioned in this Jovian-Earth comparison is Jupiter’s obliquity is 3.1 degrees, while Earth’s is currently 23.44 deg. The effect of this obliquity difference is quite clear when you examine where the terminator is relative to the aurora oval in the photo of both provided above.
The photos are of opposite poles, northern pole of Earth, so rotating CCW. Southern pole for Jupiter , so rotating CW in the views shown. It might be interesting to see if Jupiter’s dark side character of the aurora shifts as Io orbits the Jovian planet every 1.7 earth day. One Jupiter rotation is 9.9 hrs, so very fast compared to our 24 hrs.
Joel makes an interesting point here. With the Earth tilted at 23.44 degrees to the ecliptic, near the summer solstice, the entire polar area remains in sunlight, and near the winter solstice, the entire polar area remains in darkness. The only times that a “dawn storm” could occur is at times near the equinoxes, when part of the polar area can shift from darkness to sunlight every day. This is further complicated by the fact that the magnetic poles on Earth are in different locations than the poles of rotation (the magnetic north pole is in Canada).
Not any longer.
It was there until 1997 on the near zero elevation , since than it is in Siberia.
There are two location of peaks in the NH of the total field, one in Canada (as you mentioned) at 58.5 microTesla and the stronger one in the Central Siberia north of the lake Baikal) at 61.5 microTesla. Compass will average out and point somewhere in the Arctic ocean in between geographic north pole and Siberian coast, but this location is in continuous drift towards the Central Siberia. Similarly at the ToA (100 km+) cosmic rays and solar wind will see the average of two.
In contrast the SP, the strongest of all is just of Antarctic (on the Australian side), it has strength just over 66 microTesla.
https://www.ngdc.noaa.gov/geomag/WMM/data/WMM2020/WMM2020_F_BoZ_MILL.pdf
Magnetic peaks strength chronology
(Note Canadian peak coincided with Maunder Minimum.
Great addition to our understanding of amazing natural effects. Also, it appears that Jupiter’s magnetic poles are offset from the geographic poles, the same as here on earth. Does this tell us something about the core of Jupiter? The common statement about the core of Jupiter is that it is mostly “liquid metallic hydrogen”, which obviously supports the magnetosphere dynamo.
Jupiter actually has three magnetic poles.
I saw a tv program about Jupiter the other day and they showed a third magnetic pole on Jupiter located near the equator.
Uranus has magnetic field at 59 degrees offset due to it displacement of rotation axis.
View of Jupiter in relation to the sun as seen from the Earth’s direction
Tom, if they find two more poles we can refer to Jupiter as LGBTQ.
There has been speculation that there might exist Earth-sized planets orbiting around gas giants like Jupiter that might be habitable, but it seems to me like the radiation environment would be too harsh for a habitable, Earth-like planet to exist around a gas giant planet.
An Earth-sized planet orbiting around Jupiter would be much too cold to be habitable, due to the distance from the sun. Such a planet would have a strong enough gravity to hold an atmosphere (probably of mostly methane), but any water present would likely be frozen. There is information that one of Jupiter’s moons (Europa) seems to be covered in ice, but it is much smaller than Earth (radius = 970 miles).
If the water hasn’t gone you’d think there would be underground rivers on Mars but any cave entrance is probably filled now with sandy stuff. Still, tracking surface water courses might indicate where to look.
A marvelous revelation! More, Please!