APOD: 2020 August 24 – Crescent Moon HDR

Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Crescent Moon in HDR." Ever heard of The da Vinci Glow (no, it's not a book by Dan Brown)? How about earthshine? For thousands of years, humans marveled at the beauty of this "ashen glow," or "the old Moon in the new Moon's arms." But what was it? No one knew until the 16th century when Leonardo da Vinci figured it out.

We can see earthshine clearly when using a photographic technique called high-dynamic-range (HDR) imaging. HDR is created by capturing and then combining several different, narrower range, exposures of the same subject matter. A total of 29 exposures (15 of the crescent and 14 of the dimmer side) were used here to create today's image of the crescent Moon. Earthshine - sunlight reflected off the Earth to the Moon and back to Earth - becomes much easier to discern. But "The da Vinci Glow" sounds better.