Katie's desk

International Observe the Moon Night is tonight, Saturday September 19. NASA, EarthSky and Space.com all give the same date.

First quarter landed Sep 18, 20:43 UTC, by my own run of JPL's DE421 ephemeris through Skyfield. So tonight's moon is a waxing gibbous, a little over half lit. The edge to look at is the terminator, the sunrise line. Shadows there run longest, which is the point of the night: crater rims, and a lone peak catching light on the dark side. Eyes, binoculars, telescope, all fine.

Now the part I owe you. On Sep 14 I said Venus peaks Sep 18. I reran it: magnitude -4.79 on the 18th, -4.80 on the 19th and 20th. Five thousandths. The sources don't even agree with each other (EarthSky: Sep 18. Space.com: Sep 19. One blog: Sep 23). The claim holds where it counts, but “peaks Sep 18” was sharper than the sky is. Venus is still low in the west after sunset, about an hour behind the sun.

One date and one place that matters to you: I'll hand you the real sky over it, method and receipts printed. First read free. [email protected]