A star twinkles for eons, then suddenly shines brighter than any other heavenly object save the sun and moon.
It’s a supernova, the titanic explosion of a great star somewhere in the Milky Way galaxy. The show in the sky can last for days or weeks.
One such stellar event, recorded around the globe in 1006, is thought to have been recorded in Arizona by an ancient Hohokam stargazer who depicted the event in rock art, said two astronomers, John Barentine of Apache Point Observatory in New Mexico and Gilbert A. Esquerdo, research assistant with the Planetary Science Institute in Tucson.
The two scientists presented their theory at the American Astronomical Society meeting this week in Calgary, Alberta.
“The supernova of 1006 was perhaps the brightest such event visible from Earth for thousands of years, reaching the brightness of a quarter moon at peak,” Barentine explained.
The discovery, if confirmed, shows that those here then were aware of changes in the night sky and commemorated them in a cultural record.
The rock art, or petroglyph, on a 2-foot-by-18-inch rock, is produced by chiseling an image into a stone with another stone, Barentine said in a telephone interview.
The suggested depiction of the supernova of 1006 came from White Tanks Regional Park near Phoenix.
That site, as with much of southern Arizona, is believed to have been populated by Hohokam from 500 to about 1100.
While many scientists have agreed for 40 years that rock art found near Peñasco Blanco at Chaco Canyon National Monument in New Mexico depicts the supernova of 1054, there is no known prior mention of the connection between the White Tanks artifact and the supernova of 1006, Barentine said.
But it’s not surprising someone on this continent recorded the 1006 event, he said. “It would have been so bright it would have cast shadows on the ground; it was that bright.”
The supernova was observed, beginning May 1, by star watchers in what we know as Asia, the Middle East and Europe, he said.
To back up their hypothesis, Barentine and Esquerdo created a model of the night sky of May 1, 1006, to show that the relative position of the supernova to the constellation Scorpius matches placement of scorpion and star symbols on the rock.
The results “are not fully conclusive,” Barentine concedes. “The proposition is advanced and supported through circumstantial evidence.”
But the scientists plan further study using chemicals to identify materials in rock varnish that could substantiate an early 11th-century date of origin.
Barentine said astronomers figure there is a supernova in the galaxy about every 100 years.
Few are visible from Earth because of dust and debris between Earth and the exploding star. The most recent supernova, observed with the unaided eye from the Southern Hemisphere, was in 1987. A supernova from a galaxy outside the Milky Way was visible. Other supernovas in more distant galaxies have been observed through powerful telescopes.