At top: mysterious zodiacal light shining behind the Faulkes Telescope North on Maui, via Rob Ratkowksi/UH High Altitude Observatory.
Now that the moon has left the early evening sky, the next several weeks present an excellent time for those in the Northern Hemisphere to look for the mysterious zodiacal light. You’ll want a rural location, and you’ll want to look west, around the time evening twilight has just faded, as full darkness falls. About 80 to 120 minutes after sunset should be about right.
From the Northern Hemisphere, the weeks around the March equinox are the best time of all to catch the zodiacal light in the evening. From the Southern Hemisphere, it’s your best time of year to see the zodiacal light in the morning, in the east just before dawn. A bright moon is up before dawn in late March. If you’re in the Southern Hemisphere, you might need to wait until early April 2019 – when the moon has waned to a thin crescent or left the morning sky entirely – to look for the zodiacal light before dawn.
This observation is not for city dwellers. But if you find yourself beneath a dark country sky – or perhaps driving along a country road after dusk – look for this eerie light.
The zodiacal light is caused by sunlight reflecting off interplanetary dust particles that orbit the sun within the inner solar system.
People at mid-northern latitudes can see the zodiacal light after dusk at present because the ecliptic – the approximate plane of the solar system – is nearly perpendicular to the horizon on March/April evenings.
At this time of year, evening watchers see the zodiacal light jutting upward from the western horizon and toward the constellation Taurus the Bull. Taurus can be identified by its two most prominent signposts, the star Aldebaran and the Pleiades star cluster.
So for the elusive zodiacal light – pointing upwards into Taurus – look in the western sky, as dusk gives way to nightfall, these next few weeks.
Bottom line: The zodiacal light is a pyramid-shaped light. It’s west after true darkness falls for the Northern Hemisphere (east before dawn for the Southern Hemisphere) around the March equinox.