A faint oval glow visible in the night sky at the antisolar point (directly opposite the Sun), caused by backscattered sunlight from interplanetary dust particles. It appears as a brightening of the zodiacal light band.
From German 'gegen' (against) and 'schein' (shine), literally meaning 'counterglow'. The term was introduced by German astronomer Theodor Brorsen in the 1850s who first systematically studied this elusive phenomenon.
The gegenschein is like seeing Earth's shadow cast on the solar system's dust! This ghostly glow occurs because dust particles directly opposite the Sun exhibit a 'backscatter surge' - the same effect that makes your shadow's head appear brighter when cast on dewy grass.
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