It was retrieved by divers off a Greek island in 1900 and remained a mystery until 2006, when a team of researchers at Cardiff University in Wales used three-dimensional tomography to unlock its secrets. What they learned astounded everyone.

The Antikythera mechanism was built by the Greeks in 150 B.C. to 100 B.C. and was lost at sea. The device was bronze and housed in a wooden box. It consisted of several dials connected to 30 precision hand-cut gears mounted on a hand-driven turntable that gave an epicyclic motion.

The mechanism, which resembled a well-made 18th century clock, was used to predict the movements of the sun, moon and five known planets, as well as lunar and solar eclipses. It was, according to one scientist, essentially an analog computer for astronomical calculations. Nothing even remotely comparable appeared in Europe for a millennium.

The purpose was likely to aid in ship navigation but whether this was a “one-of-a-kind” device made by some unknown genius or something more remains to be seen.

Focus on the planets

The visible planets are evenly divided in the sky this month, with the morning being the best time to view Mars and Jupiter while the optimum time to check out Venus and Saturn is during the evening hours.

Mercury is lost in the glare of sunrise during April.

Venus blazes high in the west at sunset where it outshines everything but the moon. Look for Venus very near the Pleiades star cluster on April 11.

Mars is very low in the southeast at dawn where, at 165 million miles distant, little of note can be seen.

Jupiter rises in the southeast about an hour before dawn as April opens and around 11 p.m. by month’s end. Many of the surface features of Jupiter, such as its bands, will be readily visible as are its major moons.

Saturn is high in the south at nightfall near the bright star Regulus of Leo the Lion. Saturn’s fabled ring system is still tilted for favorable viewing but is starting to close, so take advantage of this opportunity that will not arise again for several years.

Uranus is paid a close visit by Mars on April 28 as the Red Planet passes to within less than a degree; however, even a good telescope may have difficulty picking far distant Uranus out of the brightening sky.

Neptune is lost to view this month.

Pluto is no longer a planet but it resides not far from Jupiter this month where it is only one-three-millionths as bright!

April events

1 Sunrise, 6:17 a.m.; sunset, 7:02 p.m.

2 Full Moon, 1:15 p.m. The full moon of April is known variously as the Pink Moon, Egg Moon, Milk Moon and Planter’s Moon.

3 The moon is at apogee or greatest distance from Earth today.

7 The bright red star Antares is to the immediate upper left of the moon about an hour before sunrise. Jupiter lies farther to the upper left.

8 Easter. The date of Easter is intended to be the Sunday after the full moon that is on or after the day of the vernal equinox.

10 Moon in last quarter, 2:04 p.m.

11 If you have a pair of binoculars, check out the western horizon about 9 p.m. where Venus and the Pleiades star cluster immediately above make for a dazzling display.

14 The waning crescent moon lies well up on the southeastern horizon about an hour before sunrise with Mars directly to the moon’s upper right.

17 New moon, 7:36 a.m. The moon is also at perigee or closest approach to Earth and the combination of these two facts could give rise to abnormally high tides.

19 The thin crescent moon is sandwiched between Venus to the upper left and the Pleiades to the lower right on the western horizon at dusk. The sun enters Aries on the ecliptic.

20 The sun enters the astrological sign of Taurus but astronomically has only just entered Aries.

22 This is the peak night for the Lyrid meteor shower arising from the constellation Lyra starting around midnight and lasting until dawn. This year may see up to 20 meteors per hour although rare displays of triple this rate have been seen in the past. The Lyrids are bright, fast, and often leave persistent trails.

24 Moon in first quarter, 2:35 a.m.

25 Saturn is to the right of the moon high in the southwest during the early evening hours with Regulus immediately to the moon’s left.

30 The moon is at apogee for the second time this month. This is May Eve, sometimes listed as a cross-quarter day rather than May 1 or Beltane. Sunrise, 5:27 a.m.; sunset, 7:39 p.m.

Send astronomical queries to Clair Wood at cgmewood@aol.com or c/o Bangor Daily News, Style Desk, P.O. Box 1329, Bangor, Maine 04402.