Skylights: March 2022

March is said to come “in like a lion, out like a lamb,” as this familiar phrase indicates the position of the zodiacal constellations as they appear in the evening sky, which undergoes some fairly significant changes over the course of the month. 

At the start of March, we see Leo, one of the few constellations that resembles its namesake, fully risen in the east.

At the conclusion of March, with twilight extending well into the 8 o’clock hour, Aries, the Ram, which can also be classified as a lamb, descends towards the western horizon, giving us “out like a lamb.”

And with Aries goes our only planet in the evening sky, Uranus. Easily visible with binoculars even under bright sky conditions, Uranus can be found about midway between the stars Hamal (Alpha Arietis) and Menkar (Alpha Ceti), although it has moved slightly east of the line connecting the two 2nd magnitude stars. The waxing crescent Moon is within 4 degrees, just below Uranus, on the 8th.

Jupiter, which has been the beacon of the evening sky for the past several months, reaches conjunction on the 5th, and returns as a morning planet thereafter, becoming visible low in morning twilight by the end of the month.

The remainder of the planets can all be seen in the morning sky.

Mercury is a morning planet during March, though it approaches inferior conjunction on April 2, so it is best observed early in the month. There are two notable planetary conjunctions involving Mercury. Mercury passes just 3/4° from Saturn on the 3rd, and a more challenging pass 1° from Jupiter on the 21st through bright twilight.

Venus and Mars, which have been moving in parallel through Sagittarius over the past month,  continue their eastward motion together through the early part of the month, with Mars crossing into Capricornus on the 5th, followed by Venus on the 6th.

As Venus approaches its greatest elongation, 46° west of the Sun on the 20th, Mars appears to pull away from Venus. Note that due to the geometry of the Sun-Venus-Earth angle, the times of maximum elongation of Venus (and Mercury) coincide with the time that the planet is 50% illuminated, appearing as a “quarter Moon” phase.

By mid-month, Saturn becomes visible slightly before the onset of twilight, and on the 24th, Venus forms the apex of an 8-degree-wide isosceles triangle with Saturn and Mars. The three planets tighten a bit over the final days of the Month, with Saturn between Venus and Mars on the 31st. The best grouping occurs on the 28th, when the waning crescent Moon passes a few degrees below the planetary triplet. 

Neptune reaches conjunction on March 13, and is not in favorable viewing position at any time in March.

With the shift to Daylight Saving Time (UTC-4) occurring on the 13th, post 7pm sunsets begin on the 22nd. The Sun will not set earlier than 7pm again until September 12. This also shifts sunrise an hour later, and we will have one sunrise later than 7am, on the 13th, before the lengthening daylight extends it back to the 6am hour the following day. By the end of the month, sunrise will occur just a few seconds after 6:30am.

The Sun passes north of the celestial equator at 11:33 EDT on the 20th, marking the equinox and the start of northern hemisphere spring.

The lunar cycle tracks closely with the dates this month, with new Moon occurring on the 2nd, beginning Lunation Number 1227. With the ecliptic angle having the highest inclination over the western horizon during March evenings, this is the best time of year for observing the waxing crescent Moon with its Earthshine. 

First quarter Moon occurs within the Winter Hexagon on March 8.

At 7:53pm on the 15th, the dark limb of the 11-day gibbous Moon occults 3rd magnitude Eta Leonis. The star reappears from behind the bright limb near Mare Crisium 76 minutes later.

The Full Worm Moon occurs on the 18th, which is unfavorable timing as mid-March is the ideal time for running the annual Messier Marathon, when all 110 objects of Messier’s catalog of deep sky objects can be observed in a single night.

Last quarter Moon occurs on the 25th, inside of the teapot asterism of Sagittarius.

Dwarf planet Ceres, in Taurus, passes the Davis’ Dog asterism as it progresses eastward. At magnitude 9, Ceres should still be easy to track with binoculars or a small telescope.

 Asteroid 16 Psyche reaches opposition this week, in Leo. This is the target asteroid of the NASA Psyche mission, which launches on August 1 and will arrive at 16 Psyche in 2026. The 226km iron-rich asteroid is 2.23 AU away, and shines at magnitude 10.4, so a small telescope is best to spot it.

Comet 19P/Borrelly, at an estimated 9th magnitude, is located just a few degrees west of the Pleiades, and passes within 3° of Bharani (41 Arietis) on the 4th, ½ ° from HD 20644 on the 12th, and ½ ° from Atik (omicron Persei) on the 19th & 20th.

Looking to the stars beyond, early March is notable as one of the four times of the year when the  position of the pointer stars of the Big Dipper align with our clock. At midnight, the pointer stars are aligned directly above Polaris, and although they are partially hidden by twilight, at 6pm they are due east, and at 6am they are due west. If we could see their noontime position, they would be directly below Polaris, just above the northern horizon.