A basic principal of electromagnetics is that when a conductor moves through a magnetic field, an electric charge is induced, No scientifically literate person denies this.
Spectrograph analysis of comets prove they contain electrically conductive materials.

Since they are moving through a magnetic field [the interplanetary magnetic field of the Sun], they are inducing an electric charge. Since they are traveling at considerable rates of speed through a magnetic field in a vacuum, it makes the comet an almost perfect capacitor, and the only opportunity it has to discharge is by interactions with the solar wind and close encounters with objects of differing electrical potential. The theory that the tails of comets are made of material blown away from the comet by the solar wind is totally incorrect.

The double tail of many comets is a result of two different phenomenon occurring simultaneously, one is caused by the exact same principal behind florescent lights to, and is explained by the electric universe theory.