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Earth Aurora: Chandra Looks Back At Earth
A team of scientists observed Earth’s north polar region ten times
during a four-month period in 2004. As the bright arcs in this sample
of images show, they discovered low-energy (0.1 - 10 kilo electron
volts) X-rays generated during auroral activity. Other satellite
observatories had previously detected high-energy X-rays from Earth’s
auroras.
The images – seen here superimposed on a simulated image of the Earth –
are from approximately 20-minute scans during which Chandra was pointed
at a fixed point in the sky while the Earth’s motion carried the
auroral region through the field of view. The color code of the X-ray
arcs represents the brightness of the X-rays, with maximum brightness
shown in red.
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 (see the accompanying illustration).
| Fast Facts for Earth Aurora: |
| Credit |
NASA/MSFC/CXC/A.Bhardwaj & R.Elsner, et al.; Earth model: NASA/GSFC/L.Perkins & G.Shirah |
| Scale |
Distance from the North pole to the black circle is 3,340 km (2,075 miles) |
| Category |
Solar System |
| Observation Dates |
10 pointings between 16 December 2003 - 13 April 2004
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| Observation Time |
3 hours |
| Obs. IDs |
100039-100048
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| Color Code |
Intensity |
| Instrument |
HRC |
| References | Anil Bhardwaj et al. 2005, Journal of Atmospheric and Solar-Terrestrial Physics (in press) |
| Distance of Chandra from Earth at time of observation |
About 120,000 km |
| Release Date |
December 28, 2005 |
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