Stonehenge an engineering marvel

loading...

Sacred monuments

Stonehenge is a concentric ring of circles encompassing far more than the main ring everyone pictures when the name is mentioned. Given the builders’ level of technological sophistication, it should be listed as one of the great engineering feats of ancient times. The outer ring is a trench several feet deep and 300 feet in diameter likely dug with deer antlers and crude stone tools. Inside is an earthen ring 6 feet high that was made from dirt excavated during the ditch digging. Next came a ring of 56 Aubrey holes named after their 17th century discoverer. Cremation remains in the holes dated to about 1850 B.C. These were followed by two more rings of holes and then the most familiar of Stonehenge’s structures, the Sarsen circle.

The Sarsen circle consisted of 30 upright stones, each about 18 feet in length, and weighing in excess of 25 tons. Their base was buried to a depth so that, when capped with lintel stones of similar shape and size, the ring was 15.5 feet high. A ring of 61 “bluestones” followed that were smaller in size, about 5 tons each, but were quarried and hauled from a site in Wales that is 130 miles from Stonehenge.

Close to the center of Stonehenge are five “trilithon” stone arches that are 25 feet high, with each stone weighing more than 50 tons. The arches are spaced so as to resemble a giant horseshoe in shape. Within this structure is a smaller horseshoe of 19 bluestones and then in the dead center of the complex is the “altar stone,” a huge flat slab that rests on stone supports. Outside of the complex is a solitary “heel stone” that is about 225 feet down an avenue from the altar stone. Astronomer Gerald Hawkins gives an estimate of 1.5 million work days of backbreaking labor to build Stonehenge. One can only look at this feat in awe and ask: Why? Next month we will look at Hawkins’ theory as to why countless people spent two millennia at this task.

Focus on the planets

Mars takes center stage in the November sky. The Red Planet will not be as big and bright again until 2018. It rises in the east at sunset and, after Venus sets, is the brightest object in the night sky after the moon. It will be at its best on Nov. 7 when it is 43 million miles from Earth, giving viewers with telescopes an excellent opportunity to see many of the Red Planet’s surface features.

Mercury makes an appearance very low on the southwestern horizon early in the month. Look for Mercury far to the lower right of Venus about a half-hour after sunset Nov. 3-9.

Venus is brilliant well up in the southwest at sunset and remains in view until about 8 p.m. Look for a thin crescent moon to the immediate lower left of Venus on the evening of Nov. 5. Viewers with a telescope will note that Venus is half in light and half in darkness around this date.

Jupiter may be found on the predawn southeastern horizon by the second week of the month. The giant planet will climb higher in the sky, growing in brightness and size, and giving better views of its satellites and surface features, as the winter months unfold.

Saturn rises in the east around 11 p.m. as November opens and by 9 p.m. at month’s end. Saturn’s ring system is prominently displayed while its four major moons will be visible through a 4-inch or better telescope. An additional feature is the Beehive Star Cluster to the west of the ringed planet.

Uranus in Aquarius and Neptune in Capricornus are found in the south as darkness falls. The greenish disk of Uranus and the bluish disk of Neptune are visible through strong binoculars or small telescope, but planet watchers may need the aid of a finder chart such as the one in the June 2005 issue of Sky & Telescope.

Pluto is not visible in November.

November events

1 Sunrise, 6:13 a.m.; sunset, 5:17 p.m.

2 New moon, 8:23 p.m.

5 Look to the southwest about a half-hour after sunset, where Venus is joined by a sliver of crescent moon. Well to their lower left is Mercury in the company of Antares.

7 Mars is at opposition, or is in the opposite direction from the sun as seen from Earth, making it one of the best times during the year to view it. Look for the orange-red planet in the east around 7 p.m.

9 Moon in first quarter, 8:57 p.m.

10 The moon is at perigee, or closest approach to Earth.

12 The Taurid meteor shower peaks around this date. This is normally a sparse display of slow-moving fireballs, but this year’s peak near the new moon may help the normally undistinguished display. Look for an occasional meteor from the vicinity of Taurus over the next several days.

13 Mars is the fiery red “star” to the lower left of the moon this evening.

16 Full moon, 7:56 p.m. The full moon of November is called the Frost Moon or Beaver Moon.

17 The Leonid meteor shower peaks tonight. Normally exhibiting a rate of up to ten meteors per hour, this years proximity to the full moon will essentially screen the meteors from view.

21 Check out Saturn near the waning moon on the northeastern horizon around 11:00 p.m.

22 The sun enters the astrological sign of Sagittarius but astronomically is still in Libra.

23 The sun enters Scorpius on the ecliptic. The moon is at apogee, or farthest distance from Earth. The moon is in its last quarter, 5:12 p.m.

28 The southeast predawn sky host of four heavenly bodies tilted in an ascending line from left to right. Starting at the bottom, these are Mercury, Jupiter, the crescent moon, and the bright star Spica.

29 The sun enters Ophiuchus on the ecliptic. Note that this not one of the twelve traditional houses of the sun or zodiac.

30 Sunrise, 6:51 a.m.; sunset, 3:57 p.m.

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