Journal Highlights

Iron ions discovered in the Earth’s magnetosphere

Editor’s Highlight—

 

Apparently the Earth's magnetosphere is iron-fortified, just like your breakfast cereal. Not only does this paper present the discovery of singly-charged iron ions but also tests three possible sources for these ions, concluding that they originate from the Earth’s ionosphere. The count rates are very small, but the instrument on Geotail is capable of distinguishing them, and approximately 21 years of Geotail data provide a large timeline of statistics about their characteristics. The counts for other charge states of iron is inconsistent with a solar source, and comparison with the flyby of Cassini/CHEMS, a nearly identical instrument, shows the values to be inconsistent with an interplanetary dust source. The variation of the Fe+ count rate with solar extreme ultraviolet radiation photon flux is dramatic and supports the claim that they come from the Earth’s upper atmosphere.