Earth Sky News for February 24: Zodiacal light glowing pyramid after dark

Zodiacal light glowing pyramid after dark

Moonless evenings in February, March and April present the best time of year to see zodiacal light in the Northern Hemisphere evening sky. Meanwhile, from the Southern Hemisphere, the zodiacal light is best seen before dawn during these months of the year. The light appears when the evening twilight has left the sky (about 80 to 120 minutes after sunset). It looks like a hazy pyramid of light in the west after true darkness falls.

This light can be noticeable and easy to see from latitudes like those in the southern U.S. I’ve seen it many times from the latitude of southern Texas, sometimes while driving a lonely highway far from city lights, up to one hour or so after evening dusk leaves the sky. In that case, the zodiacal light can resemble the lights of a city or town just over the horizon.

Skywatchers in the northern U.S. or Canada sometimes say wistfully that they’ve never seen the zodiacal light. But on February 6, 2013 – on our Facebook page – we received the beautiful photo above from Jim Peacock in northern Wisconsin. He captured the zodiacal light over Lake Superior. Sometimes the camera will pick up faint objects that the eye can’t see. But Jim said this northern Wisconsin zodiacal light was visible to the eye. He said:

Yes, it was very visible to the eye … it reached high above the horizon. Was so cool to see over Lake Superior.

You definitely do need a dark sky location to see the zodiacal light, someplace where city lights aren’t obscuring the natural lights in the sky. Remember, the zodiacal light is a pyramid-shaped glow in the west after dark. It’s even “milkier” in appearance than the starlit trail of the summer Milky Way. It’s most visible after dusk at this time of year because (as seen from the Northern Hemisphere) theecliptic – or path of the sun, moon, and planets – stands nearly straight up with respect to the horizon after the sun sets in February and March

The zodiacal light can be seen for up to an hour after dusk. Unlike twilight dusk, though, there’s no rosy color to the zodiacal light. The reddish skies at dusk and dawn are caused by Earth’s atmosphere, and the zodiacal light originates far outside our atmosphere. When you see the zodiacal light, you are looking edgewise into the plane of our own solar system. The zodiacal light is actually sunlight reflecting off dust particles that move in the same plane as Earth and the other planets orbiting our sun.

Remember, if you live in the Southern Hemisphere, your late winter/early spring months (August, September, October) are the best time for you to see the zodiacal light in the evening. Right now (February, March, April), you should be looking for the zodiacal light before dawn.

Bottom line: From the Northern Hemisphere, on a moonless night, try to find the elusive zodiacal light. It looks like a hazy pyramid of light extending up from the place where the sun went down. Meanwhile, in the Southern Hemisphere now, the zodiacal light is best before dawn.



Deborah Byrd