Watch for the zodiacal light in March

Glenn K.
Glenn K. Roberts
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Though spring officially arrives this month (March 20), a viewing session out under the night sky in March still calls for lots of warm clothes. One advantage, though, is the clarity of the atmosphere at this time of the year, making any viewing endeavour a rewarding one.

As twilight falls, Jupiter is radiant high in the eastern part of the sky. This is the best time to view this magnificent planet and its four largest moons, as we are viewing it through less atmosphere, and the image will be crisper and steadier. Shining at mag. -2.3 this month, Jupiter will be visible in the night sky until the early, pre-dawn hours.

Mars rises in the east around 9:30 p.m. as March opens and is visible during twilight by the end of the month. Though never a really bright or impressive planet for casual viewing with small scopes or binoculars, Mars puts on a bit of a show every two years. March is the month when Mars (heading towards its peak apparition in April) begins to become worthwhile to look at. It will double in brightness, from mag. -0.5 to mag. -1.3, and will increase in apparent size by 25 per cent. It is best viewed around 3 a.m. when it is at its highest point, about halfway up the sky above the southern horizon.

Saturn, always a spectacular planet to look at, rises in the east about two hours after Mars. Shining at mag. 0.4, Saturn reaches its highest altitude in the pre-dawn hours. Saturn’s magnificent ring system is tilted a full 23 degrees towards Earth this month. Heading for its May 10 opposition (opposite the sun in the sky), Saturn will continue to grow brighter and bigger in the coming months.

Venus, our “morning star”, rises about two hours before the sun this month. At mag. -4.5, it is clearly the brightest object in the eastern sky; twice as bright as Jupiter. Look for a thin, crescent moon just north of Venus on the morning of March 27.

You will need a clear, unobstructed view of the eastern horizon to have any hope of seeing Mercury this month. Mercury reaches its greatest western elongation from the sun just before dawn on March 14 and, even then, will appear a scant 5 degrees (about two fingers width) above the eastern horizon., with brilliant Venus to its upper right. Binoculars will help spot the mag. 0.1 planet in the pre-sunrise haze.

During the latter half of March, if you are out in the dark countryside just after sunset, you may have an opportunity to view one of nature’s most impressive displays. Looking to the west, you may spot the zodiacal light, a pyramid-shaped haze of light extending up from the western horizon. This celestial phenomenon is caused by sunlight reflecting off countless myriads of dust particles in the plane (ecliptic) of the solar system. In the early spring (and again in the early autumn), the ecliptic is tilted at a steep angle relative to the western horizon, enabling us to catch a glimpse of the zodiacal light. This year, the best time to start looking for the light will be after March 18, when the moon is absent from the sky.

A new PANSTARRS comet has recently been discovered, which could be worth looking at later this summer. Right now, Comet K1 is a dim 10th magnitude object in Hercules – the Strongman in the pre-dawn sky. You would need a four-inch or larger telescope to spot it. More about Comet K1 in the months to follow.

March’s full moon is often referred to as the “sap moon,” as this is the month when the sap begins running in the trees, signalling the arrival of spring and new life.

The official start of spring, the vernal equinox, for us here in the northern hemisphere is on March 20. On P.E.I., it officially commences at 1:57 p.m.

Until next month, clear skies.



March 8 - First quarter moon; 9:27 a.m.

March11 - Moon at apogee (furthest from Earth); 403,010 kms.; 4:47 p.m.

March16 - Full (“sap”) moon; 2:08 p.m.

March 20 - Vernal equinox (start of spring); 1:57 p.m.

March 23 - Last quarter moon; 10:46 p.m.

March 27 - Moon at perigee (closest to Earth); 363, 581 kms.; 3:34 p.m.

March 30 - New moon; 3:45 p.m.


Glenn K. Roberts is a member of the Charlottetown Centre of the Royal Astronomical Society of Canada (RASC). His column appears in The Guardian once a month. He welcomes comments from readers. Anyone who would like to comment on his column is encouraged to email him at

Organizations: Royal Astronomical Society of Canada, Charlottetown Centre

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