APOD: 2024 December 27 - Planet Earth at Twilight

Good morning, Rallypoint. Welcome to the Astronomy Picture of the Day (APOD) for December 27, 2024.

Today's photo is one from the APOD archives...all the way back to Expedition 2 (2001). We see here the 'terminator' between light (the Sun is to the right) and dark. The colors between the two are due to the diffraction of sunlight by the atmosphere. If you've fiddled with photography to any extent, you've probably heard the terms 'golden hour' (hour after/before sunrise/sunset) and 'blue hour' (hour after/before sunset/sunrise). That's the visual evidence of the terminator on the Earth's surface.

At the equator, the terminator is hard to keep up with (it moves at about 1,070 miles per hour). But at either pole, you can walk faster that the terminator moves...one of the little oddities of this place we call home.