Elusive Mercury puts on greatest display in March

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Sacred monuments

Near the town of Oldcastle, Ireland, a series of stone cairns, dating to around 3500 B.C., lay scattered over three hills known as the Loughcrew complex. The largest of these, Cairn T, is 120 feet in diameter, rises 900 feet above sea level and at one time was covered with white quartz. It has a passageway that leads into a central chamber containing several carved stones with the most ornate one, called the ‘equinox stone,’ situated against the back wall facing the entrance.

The stone gets its name from the fact that the Sun’s rays, on the date of the two equinoxes, shine down the passage and illuminate the stone. The rays illuminate a carving of eight rays coming from the Sun that are thought to represent the two equinoxes, two solstices, and four cross-quarter days of the ancient Celtic calendar that was divided into eight primary divisions. Between 1986 and 1990, a local researcher noticed that the rays at the solstice matched vertical markings on the “equinox stone” and that the cairn makers were able to measure solar motion with sufficient accuracy to identify leap years. Legend has it that a side chamber of Cairn T is the resting place of Ollamh Fodhla, Ireland’s first lawgiver, who died about 1277 B.C.

Focus on the planets

Oddly enough, normally elusive Mercury puts on the best planetary display in March as it makes its best evening appearance of the year.

Mercury starts the month relatively low on the western horizon about a half hour after sunset. The planet climbs a little higher each evening until it is at maximum height on March 12. There are no stars in the area to confuse with the planet and, on March 11, the thin crescent moon is just to its upper left.

Venus is lost in the Sun’s glare all month as it moves towards superior conjunction, on the far side of the Sun as viewed from Earth on March 31.

Mars may be found on the southeastern horizon about an hour before sunrise. Mars is nestled among the stars of Sagittarius and will appear tiny even through a telescope but its reddish hue should distinguish it from its surroundings,

Jupiter comes up in the southeast around 8:30 p.m. as March opens and shortly after sunset by month’s end. Jupiter will be the brightest point of light in the sky and viewers will get a special treat on the nights of March 16-17, when its moon Io passes across the face of the planet.

Saturn is very high in the south at dusk and will remain in view all evening. The ring system is tilted so that details such as gaps between them will be visible. The pair of bright stars directly above Saturn are Castor and Pollux of Gemini.

Neptune and Uranus rise along with the Sun and will not be visible in March.

March events

1 Sunrise, 6:14 a.m.; sunset, 5:22 p.m.

3 Moon in last quarter, 12:37 p.m.

5 The moon is nestled among the stars of Sagittarius about an hour before dawn.

6 Look for Mars immediately above the crescent moon an hour before sunrise.

8 The moon is at perigee, or closest approach to the Earth, tonight.

10 New moon, 4:12 a.m.

11 The thin crescent moon is to the immediate upper left of Mercury about 45 minutes after sunset. The Sun enters the constellation Pisces on the ecliptic.

15 The Ides of March. Not a good day for Julius Caesar. The term Ides in the ancient Roman calendar simply meant the 15th day of March, May, July, and October, and the 13th day of all others.

17. St. Patrick’s Day – time to plant peas according to the Almanac. Moon in first quarter, 2:18 p.m.

19 Moon at apogee, or furthest distance from the Earth, today. Look high in the south around 8:00 p.m. to see the moon forming a line with Castor and Pollux. The bright “star” to the moon’s lower right is Saturn.

20 Spring or vernal equinox, 7:33 a.m. This is the point at which the Sun appears to cross the celestial equator into the northern hemisphere. The Sun enters the astrological sign of Aries but astronomically is still in Pisces.

25 Full moon, 3:59 p.m. The full moon of March is called the Sap Moon, Crow Moon, or Lenten Moon.

27 Easter. There is a formula to determine the date of Easter but, in practice, it is the first Sunday after the first full moon following the spring equinox.

31 Venus is at superior conjunction, on the far side of the Sun as viewed from Earth, and passes into the evening sky for the spring and summer months. Sunrise, 5:19 a.m.; sunset, 6:01 p.m.

Note: The old adage that “March comes in like a lion and goes out like a lamb” likely comes from the fact that Aries is setting in the west as Leo approaches the zenith. Check this on the star chart.

Clair Wood taught physics and chemistry for more than a decade at Eastern Maine Technical College in Bangor.