Ask A Spaceman Archive
Sep 19th: Where Are All the White Holes?

Jun 6th: How Does Light Slow Down?


If light always travels at the speed of light, how does it slow down when passing through air or water? Does it matter is light is made of particles or waves? What’s the difference between phase velocity and group velocity, and how does that all play into this?

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About Our Podcast

The 365 Days of Astronomy podcast launched in 2009 as part of the International Year of Astronomy. This community podcast continues to bring you day after day of content across the years. In 2013, we evolved to add video, and in 2015 we joined the International Year of Light.

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