Our Geocorona
Earth's hydrogen geocorona (credit: the AGU)
The Earth has a geocorona now imaged for the first time. The Lyman Alpha Imaging Camera on by Japan's PROCYON spacecraft accomplished the feat. According to the American Geophysical Union (AGU):
"the image shows the outermost layer of Earth’s atmosphere, the exosphere, that is almost entirely made up of hydrogen. The hydrogen atoms scatter photons, producing a luminous halo called the geocorona. Observing the geocorona will shed light on the last phase of an important process: the escape of hydrogen atoms from Earth into interplanetary space."
The geocorona image was obtained from over 9,300,000 miles away (~15 million kilometers) and shows the entire luminous halo stretching early nearly 150,000 miles (~240,000 kilometers) from the Earth. Since the 1970's Apollo missions it has been a goal to produce a photograph of the outermost reaches of Earth’s atmosphere. The photo likely shows the final extent of the Earth's prime ingredient of life, water, which has been separated into its hydrogen and oxygen atoms by the solar wind constantly hitting the top of the atmosphere from the Sun. A technically and scientifically important photograph indeed.
WHB