Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2004 August 25
See Explanation.  Rolling mouse over image will bring up 
an annotated version.  Clicking on the image will bring up the
highest resolution version available.
Zodiacal Light and the False Dawn
Credit & Copyright: Stefan Seip

Explanation: An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles. The triangle is clearly visible in the left frame taken in Namibia in May. Rolling the cursor over the image will bring up labels. Bright zodiacal light can be seen nearly every clear moonless morning over the next few months on images taken by the Mauna Kea, Hawaii fisheye CONCAM of the Night Sky Live project. Zodiacal dust orbits the Sun predominantly in the same plane as the planets: the ecliptic. Zodiacal light is so bright this time of year because the dust band is oriented nearly vertical at sunrise, so that the thick air near the horizon does not block out relatively bright reflecting dust. Zodiacal light is also bright for people in Earth's northern hemisphere in March and April just after sunset.

Tomorrow's picture: Cas A

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