Earthsky Interviews
Private: Twilight
10-25-2004 - Space
JB: And I’m Joel Block for Earth and Sky. Around sunrise or sunset, look around. It’s good to watch the play of light in the sky and on the ground. But, you know, if you were an astronaut orbiting Earth, you’d see the sun rise and set every 45 minutes. You’d look down on a line of color above that part of Earth where twilight is taking place. That line of twilight would be curved to match the curve of the round Earth. You’d see it in contrast to the awesome blackness of outer space.
DB: Or think about witnessing an earthly twilight from the moon. You could do that anytime from the moon’s near side, where Earth is nearly always visible hanging in space. The line of twilight is what separates Earth’s sunlit side from its night side. A belt of twilight wraps all the way around the globe.
JB: Every world orbiting a star has its own zone of twilight – its own encircling belt where night meets day. Earth’s moon doesn’t have an atmosphere, so its twilight isn’t very colorful. But imagine the dramatic colors you might see above the dense cloud tops of Jupiter – or colorful twilights from the surface of Mars.
DB: The atmosphere of Mars is thin – and the sun looks smaller from there than here. But twilight would be beautiful, thanks to wind-swept dust suspended in the Martian air. That’s our show for today. We’re Block and Byrd for Earth and Sky.