See Spica: A Sign of Summer

The spring season has just ended with summer officially arriving in the Northern Hemisphere on June 21. And one way to mark the transition from spring to summer is to find the star Spica, which now appears just past the southern meridian at dusk.

Spica, the second brightest of the three stars that form the so-called "Spring Triangle," is located within the large dim region of the constellation of Virgo.

The moon, just past first quarter, will sit well off to the right of Spica on the evening of the 23rd and will be well off to its lower left the following night.

Virgo is another of those dull star patterns that owes its importance mainly to its location within the zodiac; she is supposed to represent Astraea, daughter of Zeus and Themis, the personification of the goddess of Justice who was the last of the deities to abandon the Earth at the end of the fabled Golden Age.

Spica in fact, is the only really conspicuously bright star in Virgo. A bluish-white star of great luminosity, Spica is so far away that its light requires 262 years to travel across the vast gulf of space that separates it from the Earth. Since light travels at 186,282 miles (299,791 kilometers) per second, it is obvious that Spica must be far brighter than our Sun albeit tremendously farther away.

In fact, it's a brilliant "helium" type star, about 2,300 times more luminous than our Sun.

Spica ranks as the 16th brightest star in the night sky and can be regarded as a nearly perfect example of a star of the first magnitude. As listed in the 2007 Observer's Handbook of the Royal Astronomical Society of Canada, its magnitude is given as 0.98, though the star actually varies slightly at irregular intervals from 0.97 to 1.04. It also has a tiny invisible companion that was discovered while analyzing its light with a spectroscope back in the year 1890

The name Spica comes from the Latin "Spicum," and is said to signify a spike or ear of wheat. It is derived from the ancient allegorical drawings of the goddess whose figure was somehow or other traced around the scattered stars by the imaginations of primitive stargazers. For many parts of the classical world she was the "Wheat-Bearing Maiden." In old allegorical drawings, the goddess was shown holding several spears of wheat in each hand and Spica is in one of the ears of grain hanging from her left hand, evidently representing the harvest time which occurred when the Sun was passing this bright star.

The only astronomy guide which outlines the stars of Virgo differently and hence "goes against the grain" (no pun intended) as to where Spica is located is in the famous guidebook "The Stars/A New Way to See Them" by the late H.A. Rey (1898-1977). Rey pictured Virgo lying on her back and stretched out along the ecliptic. As for Spica, Rey referred to it as Virgo's brightest jewel, but located ". . . on an unusual spot."

Henry M. Neely (1879-1963) was known as "The Dean of New York Stargazers" and lectured until he was well into his 80s at New York's Hayden Planetarium. Among the various objects that he would point out during a typical planetarium lecture, Spica was among his favorites. Back in the 1950s, Neely would often train his electric arrow-pointer on Spica and remark that:

"Spica could have been totally destroyed at the time of the signing of our Declaration of Independence, yet men would still be seeing it shining serene and undisturbed in its accustomed place until the babies who are now in their mothers' arms are aged men, cursing their rheumatism and the younger generation in the same breath." ?

Considering that the light that left Spica back in 1776 still has another 31 years to reach us, it probably will cause those "baby-boomers" born during the 1950s (like myself) who gaze at Spica tonight to pause and reflect on old Neely's prophetic words!

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Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.