A total lunar eclipse is one of the night sky’s most photogenic sights, as Scientific American readers have proved. We asked readers to send in photos of last night’s eclipse, which happened to coincide with Mars’s closest approach to Earth, making for an extra-picturesque scene. Although cloud cover prevented a view of the moon in some areas, photographers responded from Tasmania, Canada and other locales, which offered impressive views of the scarlet moon and the crimson planet.
The April 15 eclipse was one of two total lunar eclipses on the calendar this year. The next is set for October 8. That one, however, will be best viewed from the Pacific Ocean, whereas the recent sight was timed for prime viewing in North and South America.
Total lunar eclipses occur when the sun, Earth and the full moon align in a row, with Earth in the middle. When the moon passes directly through Earth’s shadow, sunlight cannot reach it directly, so it doesn’t shine as usual. The moon doesn’t disappear, either, however, because some of the sun’s light reaches it indirectly, after being bent around the edges of Earth through our planet’s atmosphere. This effect causes the moon to glow a coppery red, for the same reason that sunsets are crimson-hued: When light travels through the thickest part of Earth’s atmosphere, blue light is scattered but red shines through.