Observations

• Comets lose a considerable amount of material during its perihelion.
  • Do we really know how much material is actually lost? Not all of the material in the coma necessarily came from the comet itself. If we were to add up the mass of the vapor trails left by jets flying at high altitude, we'd conclude that they lost more mass than they took off with, when really, the vapor trails are condensation of water vapor that was already in the air. Similarly, comas might be effects that the comets had on the interplanetary medium, and do not speak directly to mass loss of the comet itself.
  • Related to this would be an estimate of how much friction comets encounter. CLC is contending that the comets build up a charged double-layer that insulates them from their surroundings, which is known as a detached bow shock for atmospheric meteroids. (See Meteoric Airbursts / General Principles.) This is consistent with the presence of dust on the surface of comets — if the solar wind directly impacted the comets, they would be swept quite clean. Only if the surface is shielded from the solar wind by a boundary layer could this be possible. But if we knew how much friction the comet encounters, and compare that with how much friction the comet should encounter just by the principles of aerodynamics, we'd know for sure, because a detached bow shock greatly reduces the friction.
  • Along these lines, here is a quote from Wikipedia. Note that they felt obligated to phrase the whole thing in terms of the magnetic field as a fluid, but this can easily be mapped to a more mechanical understanding.

    Because the relative orbital speed of the comet and the solar wind is supersonic, a bow shock is formed upstream of the comet in the flow direction of the solar wind. In this bow shock, large concentrations of cometary ions (called "pick-up ions") congregate and act to "load" the solar magnetic field with plasma, such that the field lines "drape" around the comet forming the ion tail.^[55]

  • Comets can flare up when they pass through a CME.

    If the ion tail loading is sufficient, then the magnetic field lines are squeezed together to the point where, at some distance along the ion tail, magnetic reconnection occurs. This leads to a "tail disconnection event".^[55] This has been observed on a number of occasions, one notable event being recorded on April 20, 2007, when the ion tail of Encke's Comet was completely severed while the comet passed through a coronal mass ejection. This event was observed by the STEREO space probe.^[56]

• There is evidence that comets are negatively charged (at least at their surfaces).
  • This would make sense if they are surrounded by a positively charged boundary layer.
  • But this does not mean that they have a net charge — this would just be a layer of charge induced by the positive sheath, and would be restricted to the surface.
• Comets emit jets of gas from their interiors.
  • If frictional charging has created a positively charged sheath, and a negatively charged cometary surface, this would leave the interior positively charged, and it might be the Coulomb force that motivates the jets.
  • The fact that the jets show no effects of the onslaught of the supersonic solar wind (i.e., 400+ km/s) proves that they are being emitted into a stagnant sheath, which is only possible with frictional charging.
• The coma always points away from the Sun.
  • This necessitates that the solar wind speed be great compared to the comet speed. Halley's Comet has a maximum speed at perihelion (0.57 AU) of 54 km/s. (See Halley's Comet) The solar wind typically has a speed of at least 400 km/s.
• The coma can be striated.
  • Fluids dynamics can't explain this.