Bob Moler's Ephemeris Blog

This is Bob Moler with Ephemeris for Tuesday, December 2nd. Today the Sun will be up for 9 hours and 1 minute, setting at 5:03, and it will rise tomorrow at 8:02. The Moon, 2 days before full, will set at 6:32 tomorrow morning.

I have a story about another comet ATLAS. This one is not the famous 3I/ATLAS, the interstellar interloper that is cruising through the inner solar system right now. It is another Comet ATLAS C/2025 K1, discovered in May, a little over a month before the famous one was. What we’re finding is that with comets, breaking up is not hard to do. It’s nucleus, the solid part of a comet, has broken into at least three separate pieces which are slowly separating. A comet’s nucleus is only a few miles in diameter. It is not tightly packed like a planet would be. One might think of them as kind of fluffy, especially this one, which is probably having it’s first go round close to the Sun. It appears to be an Oort cloud comet, who’s orbital period is thousands of years long.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum

Comets are named for the person or organization that discovered it. ATLAS is the Asteroid Terrestrial-Impact Last Alert System (ATLAS) search program. There’s a lot of comet ATLASes running around out there.