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We analyze the Combined Pantheon Sample of Type Ia supernovae while allowingthe velocity of light to vary as a function of the scale factor $c\proptoa^{-\zeta}$, as initiated by Barrow [1]. The variation in the velocity of lightcreates an effect akin to the refraction phenomenon which occurs for a wavetraveling in a medium with varying speed of wave. We elucidate the role of thelocal scale of gravitationally-bound regions in assisting the refraction effectto manifest. The refraction effect alters the redshift formulae (Lemaitre,distance-vs-z, luminosity distance-vs-z) and warrants a new analysis of thePantheon dataset. Upon a reformulation of the distance-redshift relations, weachieve a high-quality fit of the Pantheon dataset to the variable light speedapproach; the fit is as robust as that obtained in the standard $\Lambda CDM$model. We find that the Pantheon dataset is consistent with the variable lightspeed of the functional form: $a\propto t^{\mu}$ and $c\propto a^{1-1/\mu}$with (i) the cosmic age $t_{0}\approx 13.9$ Gy as a free parameter, while $\mu$is unspecified; and (ii) a monotonic variation in the local scale forgravitationally-bound objects (applicable to the emission sources and the SolarSystem-based apparatus/observer). Due to the agent in (ii), the high-z portionof the Pantheon dataset would produce an "effective" $H_{0}$ estimate which is10 percent lower than the $H_{0}$ estimate obtained from the low-z portion ofthe dataset. We offer an alternative interpretation of the acceleratingexpansion by way of variable speed of light, and as a by-product of the agentuncovered in (ii), a tentative suggestion toward "resolving" the ongoingtension in the Hubble constant estimates.  [1] J.D. Barrow, Cosmologies with Varying Light-Speed, Phys. Rev. D 59,043515 (1999); arXiv:astro-ph/9811022

Analyzing Pantheon SNeIa data in the context of Barrow's variable speed of light