[Physics] Why is Cherenkov Radiation faint blue in colour

Question

In 1934, Cherenkov discovered that electrons moving with large constant velocities through polarizable media caused a faint bluish glow. 'Why is the radiation blue in colour? How can a charged body moving with constant velocity emit an electromagnetic radiation?'

Answer 1

'Why is the radiation blue in colour?

From the wiki article

The frequency spectrum of Cherenkov radiation by a particle is given by the Frank–Tamm formula. Unlike fluorescence or emission spectra that have characteristic spectral peaks, Cherenkov radiation is continuous. Around the visible spectrum, the relative intensity per unit frequency is approximately proportional to the frequency. That is, higher frequencies (shorter wavelengths) are more intense in Cherenkov radiation. This is why visible Cherenkov radiation is observed to be brilliant blue. In fact, most Cherenkov radiation is in the ultraviolet spectrum—it is only with sufficiently accelerated charges that it even becomes visible; the sensitivity of the human eye peaks at green, and is very low in the violet portion of the spectrum.

Italics mine.

How can a charged body moving with constant velocity emit an electromagnetic radiation?'

It moves with constant velocity until it meets and interacts with the field of an atom/molecule.

From the wiki link again:

As a charged particle travels, it disrupts the local electromagnetic field in its medium. In particular, the medium becomes electrically polarized by the particle's electric field. If the particle travels slowly then the disturbance elastically relaxes back to mechanical equilibrium as the particle passes. When the particle is traveling fast enough, however, the limited response speed of the medium means that a disturbance is left in the wake of the particle, and the energy contained in this disturbance radiates as a coherent shockwave.