Are there comets without tails? Why do comets look like a hazy disk far from the Sun and Earth?

At large distances from the Sun, any comet looks like a hazy speck, that is, it has no tail. When approaching the Sun, the comet nucleus heats up and gas and dust are released from it, which, under the influence of the pressure of solar radiation and solar wind, form a tail. In addition, at large distances from the Sun, the phase angle of the comet is very small and the comet is observed from the Earth, as it were, in full face.

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