Sacred monuments

In the Mayan city of Uxmal in Mexico are the ruins of an observatory dating to about A.D. 600. It was used to plot the synodic period of Venus, the time between two appearances of the planet at the exact same point in the sky. They used the southernmost rising point of Venus as their marker but what is remarkable is how often they used this event and other celestial happenings in the construction of calendars.

The Mayans had no less than six calendars. There was one now called “tzolkin” that divided 260 days into 13 months of 20 days each. This was used for determining the time for various ceremonies and sacrifices. They had an annual calendar of 365 days divided into 18 months of 20 days each plus 5 days left over. These were considered extremely ominous and were used to appease the gods, fast and sacrifice.

The Mayans also had a lunar calendar based on the phases of the moon. The synodic period of Venus, 584 days, was the basis of a fourth calendar which, because the Mayans associated Venus with war, was used to determine when to attack enemies. A fifth calendar correlated the annual calendar with the Venus calendar and contained 2,290 days. This figure was 8 x 365 days or 5 x 584 days, linking the two together. Finally a “great cycle” contained 37,960 days or 104 years and incorporates the tzolkin, annual and Venus calendar periods. With all of these to contend with, being an astrologer for the Mayan culture could not have been a simple task!

Focus on the planets

Mercury makes an appearance in the latter half of August, where it may be seen in the company of Saturn low in the east-northeast about an hour before sunrise.

Venus opens the month well up on the western horizon shortly after sunset. Look for a thin crescent moon very close to Venus on Aug. 7.

Mars rises in the northeast around midnight at midmonth but the best time to view the Red Planet is at morning twilight when it is high in the south. Mars will continue to grow in size and brightness in August as the faster Earth catches up with it.

Jupiter is found well to the upper left of Venus at the start of August but the giant planet moves closer to its much brighter neighbor each night on the way to a spectacular pairing at month’s end.

Saturn lies well up on the eastern horizon a half-hour before sunrise by midmonth. Take note on Aug. 23 when Mercury is just below Saturn.

Uranus is high in the south virtually all night but is said to be most readily visible around 1 a.m. when its blue-green disk of Uranus may be spotted by means of binoculars.

Neptune will be most readily visible around Aug. 8 when it may be spotted as a blue-gray disk after midnight high in the south among the stars of Capricornus the Sea Goat.

Pluto requires a minimum of an 8-inch telescope and finder’s chart to have any chance of spotting this small and distant planet.

August events

1 Sunrise, 5:21 a.m.; sunset, 8:02 p.m. Today is Lammas or “Loaf Mass,” a cross-quarter day marking the midpoint between the summer solstice and fall equinox.

4 The moon is at apogee, or farthest distance from the Earth, today.

5 New moon, 11:05 p.m.

7 Look for the thin crescent moon immediately to the right of Venus after sunset. Jupiter is far to the upper left where the moon will pay it a visit on the evening of Aug. 9.

10 The Sun enters the constellation of Leo the Lion on the ecliptic.

12 Tonight begins the peak time to view the Perseid meteor shower. The best time is from after midnight until dawn when the moon has set. The heaviest display is from the northeast out of the constellation of Perseus, where you can expect to spot a meteor’s fiery trail every minute or so.

13 Moon in first quarter, 10:39 p.m.

19 Full moon, 1:54 p.m. The full moon of August is called the Fruit Moon, Green Corn Moon or Grain Moon. The moon is at perigee, or closest approach to the Earth, today, and the combination of these two events means unusually high tides can be expected. Check out Jupiter as it nears Venus on the southwestern horizon tonight on its way to their meeting at month’s end.

23 The sun enters the astrological sign of Virgo but astronomically is still in Leo. Look for Mercury low in the east-northeast, and just below Saturn, just before sunrise.

24 Look for the moon well up in the east after midnight. Mars is the glowing red dot to its lower right.

26 Moon in last quarter, 11:19 a.m.

31 The long-awaited meeting of Jupiter and Venus is happening low in the west at twilight. 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.