On February 28, 2007, NASA's New Horizons spacecraft made its closest approach to Jupiter on its ultimate journey to Pluto. This flyby gave scientists a unique opportunity to study Jupiter using the package of instruments available on New Horizons, while coordinating observations from both space- and ground-based telescopes including NASA's Chandra X-ray Observatory.

In preparation for New Horizon's approach of Jupiter, Chandra took 5-hour exposures of Jupiter on February 8, 10, and 24th. In this new composite image, data from those separate Chandra's observations were combined, and then superimposed on the latest image of Jupiter from the Hubble Space Telescope.

The purpose of the Chandra observations is to study the powerful X-ray auroras observed near the poles of Jupiter. These are thought to be caused by the interaction of sulfur and oxygen ions in the outer regions of the Jovian magnetic field with particles flowing away from the Sun in the so-called solar wind. Scientists would like to better understand the details of this process, which produces auroras up to a thousand times more powerful than similar auroras seen on Earth.

Following closest approach on the 28th, Chandra will continue to observe Jupiter over the next few weeks. New Horizons will take an unusual trajectory past Jupiter that takes it directly down the so-called magnetic tail of the planet, a region where no spacecraft has gone before. The sulfur and oxygen particles that dominate Jupiter's magnetosphere and originate in Io's volcanoes are eventually lost down this magnetic tail. One goal of the Chandra observations is to see if any of the X-ray auroral emissions are related to this process.

By combining Chandra observations with the New Horizons data, plus ultraviolet information from NASA's Hubble Space Telescope and FUSE satellite, and optical data from ground-based telescopes, astronomers hope to get a more complete picture of Jupiter's complicated system of particles and magnetic fields and energetic particles. In the weeks and months to come, astronomers will undertake detailed analysis of this bounty of data.

SOURCE: Chandra Harvard

The blue aurora that is constantly glowing on the giant planet Jupiter.
Credit: NASA/ESA/John Clarke (University of Michigan)

Big Auroras on Jupiter

March 29, 2007: So you thought Northern Lights were big in Alaska? "That's nothing," says Randy Gladstone of the Southwest Research Institute in San Antonio, Texas. "Jupiter has auroras bigger than our entire planet."
Last month, Gladstone and colleagues used NASA's Chandra X-ray Observatory to capture this picture: (See above)

The purple ring traces Jupiter's X-ray auroras. Gladstone calls them "Northern Lights on steroids. They're hundreds of times more energetic than auroras on Earth."

Chandra has observed Jupiter's auroras many times before, but this recent dataset is exceptional both in length and quality. Gladstone hopes it will help him solve some mysteries lingering for almost 30 years.

Jupiter's auroras were discovered by the Voyager 1 spacecraft in 1979. A thin ring of light on Jupiter's nightside looked like a stretched-out version of our own auroras on Earth. But those early photos merely hinted at the power involved. The real action, astronomers soon learned, was taking place at high-energy wavelengths invisible to the human eye. In the 1990s, ultraviolet cameras on the Hubble Space Telescope photographed raging lights thousands of times more intense than anything ever seen on Earth, while X-ray observatories saw auroral bands and curtains bigger than Earth itself.

Jupiter's hyper-auroras never stop. "We see them every time we look," says Gladstone. You don't see auroras in Alaska every time you look, yet on Jupiter the Northern Lights always seem to be "on."
The purple ring traces Jupiter's X-ray auroras. Gladstone calls them "Northern Lights on steroids. They're hundreds of times more energetic than auroras on Earth."

Chandra has observed Jupiter's auroras many times before, but this recent dataset is exceptional both in length and quality. Gladstone hopes it will help him solve some mysteries lingering for almost 30 years.

Jupiter's auroras were discovered by the Voyager 1 spacecraft in 1979. A thin ring of light on Jupiter's nightside looked like a stretched-out version of our own auroras on Earth. But those early photos merely hinted at the power involved. The real action, astronomers soon learned, was taking place at high-energy wavelengths invisible to the human eye. In the 1990s, ultraviolet cameras on the Hubble Space Telescope photographed raging lights thousands of times more intense than anything ever seen on Earth, while X-ray observatories saw auroral bands and curtains bigger than Earth itself.

Jupiter's hyper-auroras never stop. "We see them every time we look," says Gladstone. You don't see auroras in Alaska every time you look, yet on Jupiter the Northern Lights always seem to be "on."

Gladstone explains the difference: On Earth, the most intense auroras are caused by solar storms. An explosion on the sun hurls a billion-ton cloud of gas in our direction, and a few days later, it hits. Charged particles rain down on the upper atmosphere, causing the air to glow red, green and purple. On Jupiter, however, the sun is not required. "Jupiter is able to generate its own lights," says Gladstone.

The process begins with Jupiter's spin: The giant planet turns on it axis once every 10 hours and drags its planetary magnetic field around with it. As any science hobbyist knows, spinning a magnet is a great way to generate a few volts—it's the basic principle of DC motors. Jupiter's spin produces 10 million volts around its poles.

"Jupiter's polar regions are crackling with electricity," says Gladstone, "and this sets the stage for non-stop auroras."

The polar electric fields grab any charged particles they can find and slam them into the atmosphere. Particles for slamming can come from the sun, but Jupiter has another, more abundant source nearby: the volcanic moon Io, which spews oxygen and sulfur ions (O+ and S+) into Jupiter's spinning magnetic field.
 

Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

SOURCE: NASA Space Weather

Related Links:

• Aurora Flare-ups on Jupiter Caused by Volcanic Moon Io
• Chandra Harvard

May 5, 2006

For the past few months, astronomers have tracked an emerging second red spot on Jupiter, at left, a growing rival about one-half the diameter of the planet's trademark Great Red Spot. The Hubble Space Telescope has now snapped the first detailed pictures of what some observers are calling Red Spot Jr.