What would be the consequence to our night sky if the star Betelgeuse exploded in January?

Well, assuming that it went supernova about 650 years ago, we should be finding out any minute now.

right now, nothing.

NO ONE would know that Betelgeuse exploded for another 645 YEARS, because it take that long for light from Betelgeuse to get to earth.

Nobody else seems to have noticed that this is a trick question.

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Betelgeuse is 642.5 light years distant. If it detonates in January, whether this January or in the past on January 1375, Betelgeuse doesn't appear in the nighttime sky because Orion is in opposition relative to Earth, close to the Sun--it would appear in our *daytime* sky in June.

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We would not notice it for 642 years.

In about 650 years, there would be a very bright star visible in daylight for a while.

Pretty supernova that would appear as a star a little brighter than Venus. Possible auroral displays.

Cheers!

A great hole would appear in Uranus.

in about 640 years we would see a nova.

Well... we wouldn't know about it for more than 600 years, so... I'd say none.