Bob Moler's Ephemeris Blog

This is Bob Moler with Ephemeris for Thursday, April 27th. Today the Sun will be up for 14 hours and 3 minutes, setting at 8:42, and it will rise tomorrow at 6:37. The Moon, at first quarter today, will set at 3:59 tomorrow morning.

It is the latter part of April or first part of May that the spring celebration of International Astronomy Day occurs. It’s generally the Saturday closest to first quarter moon. That puts it to this Saturday, two days hence. This year, the Grand Traverse Astronomical Society will celebrate the event with a Sun and Star Party at the Sleeping Bear Dunes National Lakeshore, more specifically at the Dune Climb. More on the schedule tomorrow, but only if weather permits. The time around first quarter is the best time to view the Moon, if you aren’t out to view a specific lunar feature. The rugged highlands to the south and the smooth maria or seas to the north are seen at their best near the sunrise line, we call the terminator, due to the long shadows that are cast.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –4 hours). They may be different for your location.

Addendum

The Moon for Astronomy Day, 2023, two days after first quarter or 9 days old. Some of the more prominent features labeled. Created using Virtual Moon Atlas, GIMP and LibreOffice Draw.

Translations of some lunar feature names according to Virtual Moon Atlas

Lacus Somniorum – Lake of Dreams
Mare Crisium – Sea of Crises
Mare Frigoris – Sea of Cold
Mare Humorum – Sea of Moisture
Mare Imbrium – Sea of Showers
Mare Nubium – Sea of Clouds
Mare Serenitatis – Sea of Serenity
Mare Tranquillitatis – Sea of Tranquility
Mare Vaporum – Sea of Vapors
Montes Alpes – Alps Mountains
Montes Apenninus – Apennines Mountains
Oceanus Procellarum – Ocean of Storms
Sinus Asperitatis – Golfe des Asperites
Sinus Iridium – Bay of Rainbows
Sinus Medii – Central Bay