At this time of year, a mysterious pyramid of light – the zodiacal light – is best seen in the west after sunset from Earth’s Northern Hemisphere. It’s best in the east before dawn from Earth’s Southern Hemisphere. Northerners … watch for the bright planet Venus, and some famous landmark stars and star clusters in the constellation Taurus the Bull, behind the zodiacal light in the evening now. Southerners, you have 3 planets to watch for – Jupiter, Saturn and Mars – near the zodiacal light before dawn.
We haven’t received a photo from 2020 yet that shows the zodiacal light with respect to the three morning planets, as viewed from Earth’s Southern Hemisphere. But here’s a nice shot of the planets as seen from Tucson, Arizona, earlier this week. If you’re in the Southern Hemisphere, the zodiacal light will be near this little arc of three worlds.
Since the March equinox is the Southern Hemipshere’s autumn equinox, right now is the best time for southerners to spot the zodical light in the eastern sky, before the first traces of dawn begin to light it.
Since the recent March equinox is the Northern Hemisphere’s spring equinox, right now is the right time for northerners to spot the zodiacal light in the western sky after all traces of evening twilight have disappeared. Look westward, in the direction of sunset, some 80 to 120 minutes after sundown.
From the Southern Hemisphere … your best chance to spot the zodiacal light is in the morning sky now. Look for it in the east before sunup if you live at southerly temperate latitudes – or better yet, wait until around April 14-16, 2020, when the moon will have waned a bit and will be passing the planets before sunup. The zodiacal light and the moon near Saturn, Mars and Jupiter in 2020 … that would be a nice photo is you could catch it!
Back to the Northern Hemisphere’s evening view … Taurus is a constellation of the zodiac, so during a Northern Hemisphere spring, northerners can use Taurus’ two most prominent signposts – the star Aldebaran and the Pleiades star cluster – to help guide you to the zodiacal light in the western sky. And this year, in 2020, we can use the dazzling planet Venus to locate the constellation Taurus! Because the zodiacal light juts upward from the horizon and streams through the constellations of the zodiac, Taurus serves as your faithful guide to this elusive, glowing pyramid during a Northern Hemisphere spring.
Zodiacal light is visible to our eye because it is composed of interplanetary dust particles that reflect the light of the sun. Because these dust particles circle the sun in nearly the same plane that Earth does, the zodiacal light is always seen running astride the ecliptic – Earth’s orbital plane projected onto the constellations of the zodiac.
Bottom line: For some weeks before and after the March equinox, the glowing pyramid of light known as the zodiacal light is best seen in the west after sunset from the Northern Hemisphere, and the east before dawn from the Southern Hemisphere.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.