Bob Moler's Ephemeris Blog

This is Ephemeris for Friday, July 17th. Today the Sun will be up for 15 hours and 9 minutes, setting at 9:23, and it will rise tomorrow at 6:14. The Moon, 3 days before new, will rise at 4:01 tomorrow morning.

With Comet NEOWISE visible low in the northwest around 11 pm, one might wonder just what a comet is. Comets in general scared the crap out of the peoples of Eurasia. Comets gate crashed the perfect order of the cosmos they had thought up and supposedly caused all sorts of mayhem. As far as I’m concerned this comet is the one bright spot so far this year. A comet is mostly nothing. NEOWISE has a solid nucleus which is perhaps 3 miles (5 km) in diameter and a tail of many million of miles (km) long. If that nucleus was rock instead of frozen gasses, water and pebbles one would need a good sized telescope to spot it. Instead the gasses evaporate creating a giant head that rivals Jupiter in size and a tail all considered pretty good vacuum by earthly standards.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

An animation showing the position of Comet NEOWISE at 11 pm (or approximately an hour and a half after sunset if you’re not from Northern Michigan) for Friday, Saturday and Sunday evenings July 17-19, 2020. Created using Stellarium.

Update

Comet NEOWISE from backyard over tall shrubbery 11:18 pm July 16, 2020. I didn’t have time to focus properly which actually accentuates the stars.