Sacred monuments

The moon exhibits seasonal positioning to the sun as does the Earth. In midsummer, the moon rises in the southeast and sets in the southwest while riding low in the sky. In midwinter, it rises in the northeast and passes high overhead to set in the northwest. The moon’s orbit is also inclined at a small angle to that of the Earth. This results in a period of 18.6 years for the moon to complete one eclipse cycle and a period three times that, nearly 56 years, to return to the exact same point in its orbit. One result is an exaggerated seasonal motion of the moon called a “major standstill.”

At Callanish in Scotland’s Outer Hebrides there is a Neolithic stone circle that is 41 feet in diameter. It has a row of stones running north and another south marking the true meridional direction. The ancient Gaelic name for the structure was “Cailleach na Mointeach” or the “Old Woman of the Moors.” Archaeoastronomer Margaret Ponting discovered that, at the southerly “major standstill,” the moon skims the stone lines of Callanish. Thus it was that the inhabitants of these barren islands nearly 4,500 years ago recognized and marked the cycles of the moon.

Focus on the planets

Mercury is located low on the western horizon for about a half-hour after sunset as the month opens. Look for the innermost planet to the lower right of Jupiter from the 1st to the 9th of the month.

Venus dominates the eastern horizon at dawn where, as the brightest point of light in the sky, it cannot be mistaken for anything else.

Mars is nearly invisible except with binoculars as it lies as far from the sun in space as it ever gets. Mars lies to the right of Mercury as August begins and may be found close to the much brighter Regulus on the 9th of the month. After that, it sinks out of sight with Mercury.

Jupiter remains on the western horizon about two hours after sunset as August opens but sets soon after the sun at month’s end. Although Jupiter remains in view only a short time after sunset, the movements of its four major moons are still easy to follow by telescope.

Saturn lies in the east-northeast an hour before sunrise with Venus to the ringed planet’s upper right. If you squint real hard, you can see Saturn being orbited by the Cassini spacecraft – just joking! Not a joke is the spectacular and extremely close conjunction of Saturn and Venus on the 31st of the month.

Uranus spends the month among the stars of Aquarius. Your best bet for spotting Uranus is on the 1st of the month when the nearly full moon passes just below it. Use a telescope or powerful binoculars to look for a blue-green disc about five degrees to the north of the moon. Uranus makes its closest approach to Earth, which isn’t saying much, on Aug. 27 where binoculars will show it as a green dot.

Neptune remains among the stars of Capricornus where it may be tracked with a strong telescope and a finder’s chart. The latter may be found in the April issue of Sky & Telescope.

August events

1 Sunrise, 5:21 a.m.; sunset, 8:02 p.m. Lammas, or “loaf Mass,” a cross-quarter day marking the midpoint between the summer solstice and autumn equinox. Watch for Jupiter with Mercury to the lower right in the west a half-hour after sunset. Regulus is the bright star to the right of Mercury and very faint Mars farther still to the right.

7 Moon in last quarter, 6:01 p.m.

9 Use binoculars to try to spot Mars very near Regulus very low on the western horizon about a half-hour after sunset.

10 The sun enters Leo on the ecliptic.

11 The moon is at apogee, or greatest distance from Earth. Venus shines on the northeast predawn horizon with Saturn to the lower left. The two bright stars to Saturn’s left are Castor and Pollux.

12 Tonight will be the peak night for the Perseid meteor shower derived from comet Swift-Tuttle. They originate in the northeast from the constellation of Perseus. This should be a good year with the new moon only a few days away. They speed into the Earth’s atmosphere at 37 miles per second and leave bright, persistent streaks. An average 60 meteors per hour is expected.

16 New moon, 9:23 p.m.

17 Note the thin crescent moon to the right of Jupiter about an hour after sunset.

22 The sun enters the astrological sign of Virgo but, astronomically, is still in Leo.

23 Moon in first quarter, 6:12 a.m. Antares lies close to the first-quarter moon.

27 Moon at perigee, or closest approach to the Earth, today.

30 Full moon, 10:21 p.m. The full moon of August is called the Green Corn Moon or the Grain Moon.

31 Look to the east about an hour before sunrise for an extremely close pairing or conjunction of Saturn and Venus. Sunrise, 5:56 a.m.; sunset, 7:15 p.m.

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