Astronomy Picture of the Day

Explanation: What's causing that unusual ray of light extending from the horizon? Dust orbiting the Sun. At certain times of the year, a band of sun-reflecting dust from the inner Solar System appears prominently after sunset or before sunrise and is called zodiacal light. The dust was emitted mostly from faint Jupiter-family comets and slowly spirals into the Sun. The featured composite image, acquired in mid-February from the Sierra Nevada National Park in Spain, captures the glowing band of zodiacal light going right in front of the bright evening planets Jupiter (upper) and Venus (lower). Emitted from well behind the zodiacal light is a dark night sky that prominently includes the Pleiades star cluster. Jupiter and Venus are slowly switching places in the evening sky, and just in the next few days nearing their closest angular approach.