Category: Jupiter

Jupiter has a powerful magnetic field 20,000 times stronger than the Earth’s. It is therefore of no surprise that the highly energetic and damaging particles flying around in the Earths Van Allen Belts can be found within Jupiter’s magnetosphere too. But are the mechanisms energizing these particles the same for both planets? New research suggests that the magnetospheres of Jupiter and Earth may have more in common than previously thought…

As previously reported on Universe Today, there is a possible source to the magnetospheric “hiss” that energizes protons and electrons within the Earth’s Van Allen Belts. The discovery that low frequency “chorus” waves propagating through the upper atmosphere evolve into waves that can interact with charged particles is significant in that it helps to solve a 40 year debate as to where these waves come from. Now, the nature of Jupiter’s highly energetic particles trapped in its strong magnetic field has been brought into question.

The Galileo spacecraft (pictured) measured radio wave activity inside the magnetosphere as it orbited the gas giant over eight years. According to the scientific collaboration including researchers at the British Antarctic Survey (BAS), University of California, Los Angeles (UCLA), and the University of Iowa (UI), similar low frequency radio waves may be responsible for electron energization in the Jovian high energy particle belts as in the terrestrial Van Allen Belts.

Although details on the source of Earth’s “chorus” waves are sketchy (we know they originate outside of the plasmasphere surrounding Earth and evolve into a radio wave “hiss” inside the Van Allen Belts), the source of low frequency radio waves around Jupiter comes from the interactions between the moon Io and the Jovian magnetic field.

“On Jupiter, the waves are powered by energy from volcanoes on the moon Io, combined with the planet’s rapid rotation – once every 10 hours. Volcanic gasses are ionized and flung out away from the planet by centrifugal force. This material is replaced by an inward flow of particles that excite the waves that in turn accelerate the electrons.” – Dr Richard Horne, lead author of research, British Antarctic Survey (BAS).

The interaction of Jupiter’s moons with its atmosphere is highlighted when analysing the pattern of the polar auroral regions on the planet. As the magnetic field is so strong on Jupiter, massive regions of bright emission can be seen in the UV wavelengths (pictured top). This is emission from huge auroral displays as highly energetic particles funnel down magnetic flux and interact with Jupiter’s atmosphere (similar to Earth’s auroral displays, only much bigger). There are some strange patterns in the auroral “crown” – “footprints” of the Jovian moons, Io, Ganymede and Europa. The moons emit particles which get directed down to Jupiter by the gas giant’s magnetic field. These footprints appear as little spots in Jovian polar regions, rotating with the moons as they pass through the magnetosphere.

By far the strongest influence on Jupiter’s magnetosphere, Io is constantly erupting with material, firing it through the Jovian magnetic field. Thanks to Galileo data, it appears this fast orbiting moon generates low frequency radio waves, driving the high energy particles trapped within Jupiter’s plasmasphere through wave-particle interactions.

“For more than 30 years it was thought that the electrons are accelerated as a result of transport towards Jupiter, but now we show that gyro-resonant wave acceleration is a very important step that acts in concert.” – Dr Horne

These results will have a huge impact on space weather forecasting. As the Sun erupts during periods of heightened solar activity (i.e. during “solar maximum”), the reaction of the Earth’s plasmasphere is critical to understanding the quantities of damaging high energy particles that may influence space missions, damaging satellites and causing harm to astronauts. Looking into Jupiter’s huge magnetosphere will aid understanding of our own magnetosphere, hopefully improving solar storm predictions.

Source: British Antarctic Survey

As a giant planet, Jupiter takes everything to the extreme. Even the weather. A ferocious storm raging across the cloud tops has surprised scientists: it’s churning up material that was deeper down in the planet’s atmosphere. And there’s evidence that the planet’s jet streams are generated by its own heat, and not just from the Sun.

Even in the smallest telescope, it’s easy to see the distinct atmospheric bands that stretch around the planet, like a series of stripes. The strongest winds on the planet are at Jupiter’s northern latitudes. Here the winds can howl at 600 km per hour (370 miles per hour).

But astronomers have always wondered what drives these storms? Is it energy from the Sun, or is the planet’s own heat that gets the powerful jet streams driving winds across Jupiter.

In March 2007, several telescopes captured a rare atmospheric eruption, where two brand new storms appeared in the planet’s cloud tops.

The event was so well recorded because it coincided with the New Horizons spacecraft’s flyby with Jupiter. Many telescopes, including Hubble, NASA’s Infrared Telescope Facility, and a network of smaller telescopes around the world were making support observations of Jupiter.

An international team coordinated by Agustín Sánchez-Lavega from the Universidad del País Vasco in Spain presented their findings about this event in the January 24 issue of the journal Nature.

“Fortuitously, we captured the onset of the disturbance with Hubble, while monitoring the planet to support the New Horizons flyby observations of Jupiter in its route to Pluto. We saw the storm grow rapidly since its beginning, from about 400 kilometers [250 miles] to more than 2,000 kilometers [1,245 miles] in size in less than one day,” said Sánchez-Lavega.

With the storms, the researchers observed bright plumes of material. The newly forming storms pulled vast quantities of ammonia ice and water from deep below, and pushed it up 30 km (20 miles) above the cloud tops – higher than any other place on the planet.

By modeling the event, the researchers found that their observations supported the theory that Jupiter’s jet streams, which power the storm systems, come from much deeper inside the planet. Here on Earth, radiation from the Sun heats up the high atmosphere, and gets the jet streams going. But on Jupiter, it looks like the planet’s own heat drives these jet streams, and not the sunlight it receives.

Original Source: NASA/JPL News Release