The Moon releases a stream of neutral sodium atoms that forms a long tail extending over 500,000 kilometers in the anti-solar direction. This feature cannot be seen with unaided vision from Earth. Sodium is freed from the lunar surface by micrometeoroid impacts and by photons that dislodge atoms from the regolith. Once released, sunlight pushes these atoms away from the Moon through radiation pressure.
The average density in this tail is about one atom per cubic centimeter, which makes measurements challenging. Because the Moon lacks a global magnetic field, solar wind plasma reaches the surface without substantial shielding. The sodium tail itself is neutral and therefore not guided by Earth’s magnetic field. Instead, Earth’s gravity focuses sodium atoms into a brighter region on the night side, sometimes called the sodium spot.
The tail varies in form and intensity depending on viewing geometry, the Moon’s position in orbit, and the direction of sunlight. These factors influence how radiation pressure accelerates the sodium atoms and how Earth’s gravity shapes their distribution.
iGadgetPro
The Moon releases a stream of neutral sodium atoms that forms a long tail extending over 500,000 kilometers in the anti-solar direction. This feature cannot be seen with unaided vision from Earth. Sodium is freed from the lunar surface by micrometeoroid impacts and by photons that dislodge atoms from the regolith. Once released, sunlight pushes these atoms away from the Moon through radiation pressure.
The average density in this tail is about one atom per cubic centimeter, which makes measurements challenging. Because the Moon lacks a global magnetic field, solar wind plasma reaches the surface without substantial shielding. The sodium tail itself is neutral and therefore not guided by Earth’s magnetic field. Instead, Earth’s gravity focuses sodium atoms into a brighter region on the night side, sometimes called the sodium spot.
The tail varies in form and intensity depending on viewing geometry, the Moon’s position in orbit, and the direction of sunlight. These factors influence how radiation pressure accelerates the sodium atoms and how Earth’s gravity shapes their distribution.
Visualisation of Earth's Moon — by iGadgetPro
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