An aurora is a natural light display in Earth's upper atmosphere caused by charged particles from the Sun colliding with atoms in the atmosphere. These collisions excite oxygen and nitrogen, which the
Earth's night-side upper atmosphere appears from the bottom as bands of afterglow illuminating the troposphere in orange with silhouettes of clouds at the top, and the stratosphere in white and blue at the top of the middle. Next, the mesosphere (pink area) extends to the orange and faintly green line of the lowest airglow, at about one hundred kilometres at the edge of space and the lower edge of the thermosphere (invisible). Continuing with green and red bands of auroras stretching over several hundred kilometres.