Then drive a spike to Spica


How many times have I quoted the phrase “follow the Big Dipper handle arc to Arcturus, and then drive a spike to Spica”? Orange Arcturus is the first bright star the handle points to, and blue, white Spica is the next brightest.

Virgo the Maiden is the second-largest constellation in the sky, and Spica is its brightest star. It marks the ear or spike of wheat being held by Virgo. The word Spica is Latin for ear and is believed to refer to ear of wheat. Although the winged maiden stands upright in the sky holding the ear of wheat in her left hand, Virgo is not easily identified due to the long rambling cluster of stars that make up her body.

Spica and Virgo are often associated with the Greek Goddess of Harvest, Ceres. The word cereal is derived from her name. The asteroid-dwarf planet Ceres is also named for her and is currently located in Virgo just slightly northeast of Spica but does require optical aid for viewing.

The star Antares in the Scorpius constellation and Spica are tied for the 15th-brightest star visible from Earth. Although it’s not visible as a binary, or double star, due to its 262 light years distance from us, Spica is a whirling double star. Both of its stars are larger and hotter than our sun. They are 11 million miles apart and orbit each other every 4 days. Can you imagine how fast they’re going? The primary star is more than 10 times the mass of our Sun, and about seven times wider. The secondary star is seven times the mass of the Sun, and about four times wider. That’s huge!

The combined light from both stars is 2,200 times brighter than the Sun. In fact, every star you see unaided, without binoculars or a telescope, is bigger and brighter than our Sun. Since the new moon was on May 30, this is a good time to look at them. The first quarter moon will be on June 7.

Considering their distance from us, they’re one of the nearest binary systems to our solar system. Despite that, because they’re so close to each other, they can’t be separated visually, even with a powerful telescope. It was a spectroscope that revealed Spica’s dual nature. A spectroscope is an instrument that splits light into its component colors and reveals the color shift between the two stars.

It’s also thought that both stars are egg shaped, with pointed ends facing each other. This is due to their mutual gravity as they rapidly whirl around each other. The best viewing of Spica is spring and summer, so go out and look slightly more than halfway up in the southern sky. And while you’re looking at Spica, try to envision those two giants whirling stars.

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