When a year with 365 days starts on a Sunday, like 2023, it's inevitable Friday the 13th will occur twice. In 2023 Friday the 13th comes in January and October.
Cassiopeia and Perseus are neighbors in the fall sky. Use Cassiopeia's distinctive W or M shape to locate the dimmer Perseus on autumn and winter evenings.
The Andromeda galaxy is the closest big galaxy to our Milky Way. At 2.5 million light-years, it's the most distant thing you can see with the eye alone.
Bruce McClure served as lead writer for EarthSky's popular Tonight pages from 2004 to 2021, when he opted for a much-deserved retirement. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also wrote and hosted public astronomy programs and planetarium programs in and around his home in upstate New York.