When a meteor enters the Earth’s upper atmosphere it excites the air molecules, producing a streak of light and leaving a trail of ionization (an elongated paraboloid) behind it tens of kilometers long. This ionized trail may persist for less than 1 second up to several minutes, occasionally. Occurring at heights of about 85 to 105 km (50-65 miles), this trail is capable of reflecting radio waves from transmitters located on the ground, similar to light reflecting from a mirrored surface. Meteor radio wave reflections are also called meteor echoes, or pings.