What is the difference between dusk and astronomical twilight?
Quick Answer: Dusk is the period just after sunset when the sky darkens but still has some light. Astronomical twilight is a specific phase of dusk when the sun is between 12° and 18° below the horizon, and the sky is dark enough for astronomers to observe faint stars without interference from sunlight.
Dusk is a general term for the fading light after the sun sets. It includes different stages of twilight: civil, nautical, and astronomical. Each stage is defined by how far the sun is below the horizon.
Astronomical twilight is the darkest part of dusk before true night begins. When the sun dips 18° below the horizon, the sky is fully dark and free from sunlight glow, making it ideal for astronomy.