Earth has a tail, flowing for millions of kilometres into space on its dark side

The tail of 3I/ATLAS, the third interstellar visitor observed in our solar system, has created quite a buzz - sometimes you see it, and other times you don't. This object has been classified as a comet and so developed a tail that is not quite clearly visible. However, comets are not the only cosmic bodies that have tails. Our very own planet, the one we call home, Earth, also has a tail. Recently, NASA revealed that Mercury, the closest planet to the Sun, is displaying a tail. This is nothing new, but it only becomes so at a certain time and position. Now, scientists are telling us that Earth is no exception. This tail extends for at least two million kilometres into space behind our planet, and is present on the dark side of our planet.

Mercury gets its tail from the sodium present in the planet. It starts extending outwards when it gets to its closest point to the Sun. According to NASA, scattered sunlight gives the sodium "a bright orange glow." The sodium atoms are pushed outwards due to the "radiation pressure" and strip its atmosphere, giving it a long glowing tail. In the case of Earth, it boils down to its magnetic field. Called the magnetosphere, it "dominates the behaviour of electrically charged particles in space near Earth and shields the planet from the solar wind," according to NASA.

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Plasma tail formed by solar winds

The magnetosphere also traps electrified gas, called plasma. Some of this plasma extends outwards into space, forming the tail of Earth. NASA believes it is a "return flow of plasma" that happens because of the solar wind, plasma being continuously released from the solar surface. This gives a kind of push to the magnetosphere and distorts its shape, "compressing it on the Earth's day side, like the head of a raindrop. The region is stretched on the night side, like the raindrop tail, forming a teardrop shape." This is how it also gets its name - "magnetotail".

Earth's tail possibly extends to 1,000 times Earth’s radius; however, scientists aren't sure of its exact length. According to the European Space Agency, it stretches at least two million kilometres into space on the night side of the Earth.