Chandra looks back at the Earth

In an unusual observation, a team of scientists has scanned the northern polar region of Earth with NASA's Chandra X-ray Observatory. The results show that the aurora borealis, or "northern lights," also dance in X-ray light, creating changing bright arcs of X-ray energy above the Earth's surface.

While other satellite observations had previously detected high-energy X-rays from the Earth auroras, the latest Chandra observations reveal low-energy X-rays generated for the first time during auroral activity.

The researchers, led by Dr. Ron Elsner of NASA's Marshall Space Flight Center in Huntsville, Ala., used Chandra to observe the Earth 10 times over a four-month period in 2004. The images were created from approximately 20-minute scans during which Chandra was aimed at a fixed point in the sky and the Earth's motion carried the auroral regions through Chandra's field of view.

From the ground, the aurora are known to change dramatically over time, and this is also the case in X-ray light. The X-rays in this sample of the Chandra observations, which have been superimposed on an approximate representation of the Earth, are seen here.

Auroras are produced by solar storms that eject clouds of energetic charged particles. These particles are deflected when they encounter the Earth's magnetic field, but in the process large electric voltages are created. Electrons trapped in the Earth's magnetic field are accelerated by these voltages and spiral along the magnetic field into the polar regions. There they collide with atoms high in the atmosphere and emit X-rays. Chandra has also observed dramatic auroral activity on Jupiter.

Dr. Anil Bhardwaj is the lead author on a paper describing these results in the Journal of Atmospheric and Solar-Terrestrial Physics. Dr. Bhardwaj was a co-investigator on this project and worked with Dr. Elsner at NASA's Marshall Space Flight Center while this research was conducted.

The research team also includes Randy Gladstone, Southwest Research Institute, San Antonio, Texas; Nikolai ьstgaard, University of Bergen, Norway; Hunter Waite and Tariq Majeed, University of Michigan, Ann Arbor; Thomas Cravens, University of Kansas, Lawrence; Shen-Wu Chang, University of Alabama, Huntsville; and Albert E. Metzger, Jet Propulsion Laboratory, Pasadena, Calif.

Source: Chandra X-ray Center

Related stories:

Black holes have simple feeding habits
The biggest black holes may feed just like the smallest ones, according to data from NASA's Chandra X-ray Observatory and ground-based telescopes. This discovery supports the implication of Einstein's relativity theory that black holes of all sizes have similar properties, and will be useful for predicting the properties of a conjectured new class of black holes.
Scientists Hold Seance for Supernova
Astronomers have unearthed secrets from the grave of a star that blasted apart in a supernova explosion long ago. By decoding ghostly echoes of light traveling away from the remains of a supernova called Cassiopeia A, the scientists have pieced together what the star looked like in life, and ultimately how it met its demise.
Swift satellite catches first 'normal' supernova in the act of exploding
Thanks to a fortunate observation with NASA's Swift satellite, astronomers, for the first time, have caught a normal supernova at the moment of its birth--the first instant when an exploding star begins spewing its energy into space, transforming into a supernova that during its brief lifetime will shine brighter than billions of stars combined.
Did the solar system 'bounce' finish the dinosaurs?
The sun’s movement through the Milky Way regularly sends comets hurtling into the inner solar system – coinciding with mass life extinctions on earth, a new study claims.
Galaxies Gone Wild
Interacting galaxies are found throughout the Universe, sometimes as dramatic collisions that trigger bursts of star formation, on other occasions as stealthy mergers that result in new galaxies. A series of 59 new images of colliding galaxies has been released from the several terabytes of archived raw images from the NASA/ESA Hubble Space Telescope to mark the 18th anniversary of the telescope’s launch. This is the largest collection of Hubble images ever released to the public simultaneously.
Milky Way’s Giant Black Hole Awoke from Slumber 300 Years Ago
Using NASA, Japanese, and European X-ray satellites, a team of Japanese astronomers has discovered that our galaxy’s central black hole let loose a powerful flare three centuries ago.
Action replay of powerful stellar explosion
Astronomers have made the best ever determination of the power of a supernova explosion that was visible from Earth long ago. By observing the remnant of a supernova and a light echo from the initial outburst, they have established the validity of a powerful new method for studying supernovas.
An Oxygen Factory in a Nearby Galaxy
This Chandra X-ray Observatory image shows the debris of a massive star explosion in the Large Magellanic Cloud, a small galaxy about 160,000 light years from Earth.

News discussion:

Space & Earth science news