One of history’s favorite stars is drawing eyes to the eastern skies shortly after sunset these Spring evenings.
Arcturus is the bright star directly east as darkness grips the night. It is the anchor star of Bootes the Herdsman.
The pattern of stars that make up Bootes (boo-O-tez) are one of the most recognized and talked about through ancient history. To easily find it locate the Big Dipper directly north. The handle of the Big Dipper arcs to Arcturus and following the curve you “speed on to Spica,” the brightest star in Virgo the Virgin. Bootes is imagined to be a herdsman who is wrangling the Big Bear around the sky.
The main stars of Bootes are in the shape of a kite, or ice cream cone. The beautiful golden-yellow Arcturus is at the bottom apex. It is one of the first stars with a recorded name, dating back to the ancient stargazers hundreds of centuries ago. The star Arcturus has been important to all stargazers since it was first identified on star charts in 1500 BC.
In ancient times, the whole constellation Bootes was referred to as Arcturus, the star pattern and star being the same name. The Greek word, “boots” means plowman or herdsman, and Arcturus is a Greek derivative from “arktos,” meaning bear, and “ouros,” meaning guard. Thus, the star group has been envisioned as herding the nearby Ursa Major and Ursa Minor, the Big and Little Bears around the sky.
Ancient Japanese astronomers adopted the even more ancient Chinese astronomy name for this beautiful star—Dah Jyaoo in the constellation The Great Horn. Indeed, the main outline of Bootes does resemble a horn with Arcturus at it tip.
Arcturus is the fourth brightest star in all the sky, (behind Sirius, Canopus and Alpha Centauri) and the brightest star north of the celestial equator. That would have great significance to the star worshipers of the ancient world.
Polynesian sailors called the star Hokul’a or “Star of Joy” and used it as a guide post to find the Hawaiian Islands. The Arabic world called this star Al-Harithas Sama, and considered it to be the “Keeper of Heaven.”
The physical characteristics of Arcturus are staggering.
It is a giant star, at the end of its life. It dwarfs our Sun in size, and that is a lot like the predicted fate of our Sun 4 or 5 billion years from now.
Swelled like a balloon as its hydrogen fuel has been converted to mostly helium, Arcturus would suck up the orbit of Venus if place in our Solar System. Another comparison is our Sun being the size of a garden pea (800,000 miles wide), and Arcturus the size of a cantaloupe (200 million miles wide)!
Because Arcturus is a rather close star to us, no doubt it will be one of the first star surfaces to be imaged by future space telescopes. It is already suspected that “star spots” are the cause of some light energy output anomalies, the equivalent of sunspots on our own star.
The eventual fate of Arcturus will be exploding into a supernova as the nuclear furnace runs haywire and destroys the star. Its atomic elements will be flung into outer space to be reconstituted somewhere into maybe another star, a cloudy nebula, a planet or even a human.
After all, we are all made of star dust.
Arcturus is a mere 36.7 Light Years away from our Sun. In round numbers, that’s 37 x 6 trillion miles, or 222 trillion miles away—just a stone’s throw in astronomical terms.
Arcturus was in the newspaper headline news in 1933 when the “Century of Progress” Exposition was conducted in Chicago. At the grand opening, a telescope was used to focus starlight onto a “futuristic” photoelectric cell to generate energy to power flood lights. At that time, it was thought that Arcturus was 40 Light Years away, and that was a tie-in to the previous Chicago fair in 1893, four decades before.
Tonight, in this Summer of 2008, the light that strikes your eyes left the surface of Arcturus in 1971. Someday when the star blows up it will be seen in the daylight and cast a shadow on the ground at night.
That might happen in 10 years or 10,000 years or 10 million years. But a supernova Arcturus will someday be…and that will put this special star back in the headlines!