Earth’s atmosphere extends far beyond the Moon’s orbit

The outer layer of Earth’s atmosphere extends much farther into space than previously thought. As the results of the new study suggest, it could reach as far away as 630,000. kilometers – far beyond the Moon’s orbit.

Where our atmosphere blends into space, there is a cloud of atomsów of hydrogen loosely bound by gravity to our planet. This is the so-called geocorona. It forms part of the outermost layer of the planet’s atmosphere – exosphere.

Our planet’s gaseous envelope extends far beyond the Moon’s orbit. The latest research based on data acquired by the SOHO (Solar and Heliospheric Observatory) probe indicates that this could be as far away as 630,000 kilometersów.

One of the instrumentów of the SOHO – SWAN probe, thanks to its extremely sensitive sensors, observed traces of hydrogen and determined precisely how far the geocorona’s boundaries extend. These observations can be made only at certain times of the year, when the Earth and its geocorona appear in the field of view of SWAN.

– Moon flies through Earth’s atmosphere. We were not aware of this, dopóki we had not dusted off the observations made more than two decades ago by the SOHO probe,” said Igor Baliukin of the Russian Space Research Institute, head of theówny author of publications.

It is difficult to make measurementsóin the geocorona. Until now it was thought that its boundary reaches at a distance of about 200 thousand. kilometeróin from the Earth. Recent analysis has corrected earlier findings. It is interesting to note that orbiting wokół Lagrange point’a (L1) – approximately 1.5 million kilometersów from the Earth – SOHO probe made these observations more than two decades ago, in 1996-1998. The data during this time was in the archive waiting for someone to móhead to analyze them.

The readings were taken specifically to map the geocorona with the SWAN instrument, whichóry has sensors designed to measure ultraviolet emissions from atomicóin hydrogen, the so-called Lyman-alpha line. We can’t see it from Earth – this type of radiation is absorbed by the Earth’s atmosphere. An instrument is needed to observe itów located in space.

The first telescope placed on the Moon by an astronautóin from the Apollo 16 mission in 1972 captured a suggestive image of the geocorona surrounding the Earth, shining brightly in ultraviolet light. – Astronauts on the Moon’s surface didn’t even know that they were actually inside the geocorona, admitted Jean-Loup Bertaux, coółautor of the publication and former head of theówny scientist SWAN.

The SWAN instrument can selectively measure light from the geocorona, filtering out Lyman-alpha emissions from further away. This made it possible to develop a more accurate map of the geocorona and reveal its true sizeów. It also showed how this gaseous envelope is affected by the Sun.

Sunlight squeezes hydrogen atoms in the geocorona on the Earth’s day side and produces an area of increased density on the night side. Compressed waterór on the day side has a density of about 70 atomicóIn per cubic centimeter at an altitude of 60,000. kilometerów. It dilutes to 0.2 atomsów per cubic centimeter in the Moon’s orbit.

– On Earth we would call this prówith. This additional source ofóThe hydrogen bed is not dense enough to facilitate space exploration – said Baliukin. The good news is that these particles pose no threat to space subrógników during future manned missions orbiting wokól Moon and on the Silver Globe itself.

– There is a róalso ultraviolet radiation associated with the geocorona, because hydrogen atoms scatter sunlight in all directions, but their effect on the astronautóIn the orbit of the Moon is irrelevant in poróIn relation to the headóin a source ofóradiation sources – Sun – Jean-Loup Bertaux added.

Geocorona on the night side can affect astronomical observations made near the Moon. – Space telescopes observing the sky in the ultraviolet range to study the chemical composition of stars and galaxies would have to take this into account – noted Jean-Loup Bertaux.

Sourceósource: American Geophysical Union, fot. NASA. Pictured is the Earth’s geocorona as seen from the Moon. Photo taken in 1972 as part of the Apollo 16 mission.