phi (totient) wrote,
phi
totient

transit of venus

Sounds like a cross between a cynical classicism and an Anais Nin title, doesn't it?

This coming Tuesday morning (for those of you in EDT), Venus will transit the sun. The ingress and most of the transit itself will happen before sunrise here, but the egress will be visible. Contact III is at 7:05 AM and Contact IV is at 7:25, and the half-hour starting around 7 is the most interesting visible part of the transit. Starting shortly before Contact III, expect to see some amazing phenomena: first, the Black Drop effect, which is due to the fact that the human eye can't see the Sun's edge brightness gradation because it's past saturation, and later, a halo effect observed by Lomonosov in 1761 (the last-but-one such transit) which is due to refraction in Venus' dense atmosphere.

There's a fun map showing where the transit will be visible. Notice the grey areas in Nunavut and off the coast of Antarctica; those are where night and day (respectively) will occur entirely within the duration of the transit.
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