Follow the arc to Arcturus to see 4th-brightest star in sky
With the season of spring well underway, there is a bright and magical star to view in our Arizona skies in April.
The star is known as Arcturus.
Arcturus is an amazing example of a bright red-orange giant in the constellation Bootes, the “herdsman.”
Bootes is 13th-largest constellation in the night sky and was first cataloged by the astronomer Ptolemy in the second century.
The constellation, when viewed from the darkest of skies, takes on the shape of a large kite.
Arcturus is the fourth-brightest star in the night sky and the brightest star in the northern celestial hemisphere.
On a pure and emotional level, Arcturus is most pleasing to the eye — a bright, shimmering, red-orange blazing point of light, that some 37 light years from the Earth.
The light you see from this star, rising in the east northeastern sky at 8 p.m., left the star back in 1984.
If you are old enough to remember that period in time, space shuttles were being launched to space on a regular basis!
Now, let’s take a deeper look at this unique star: Arcturus is some 26 times the size of the sun and shines with a luminosity of 170 times the sun.
Here is a size comparison of our sun and Arcturus:
The constellation of Bootes.
Arcturus, as a star, has exhausted most, if not all, of its hydrogen fuel and has thus moved off of the main sequence of sunlike stars.
In doing so, Arcturus has expanded and increased in its luminosity.
Many stars like the sun will also go down this path of stellar evolution.
The sun is some 4 billion years old; Arcturus is thought to be around 7 billion years old.
The name Arcturus is thought to have been derived from ancient Greek and means “Guardian of the Bear.”
Bootes and Arcturus are located very close to the large constellation, Ursa Major, the “Great Bear.”
The bright star appears to guard the entrance to the area occupied by this large constellation.
Many students have come to know a very simple expression to help find the star Arcturus: “Follow the arc to Arcturus.”
Follow the main stars in the handle of the Big Dipper, a more modern version of Ursa Major, and you will come to Arcturus, some 30 degrees to the lower right.
The star Arcturus is also a media star in its own right.
Back in 1933, the light of Arcturus was part of a project to open the 1933 Chicago World’s Fair.
Light from this star was imaged by a number of photocells in large telescopes and the signal was sent by phone lines to flip a switch to turn on the lights at the fair.
This came some 40 years after the previous World’s Fair in 1893. Many thought then that Arcturus was 40 light years away.
Finally, Arcturus is a star that is not moving in a circular orbit around our Milky Way Galaxy, but rather moving perpendicular to that plane.
Go out and enjoy this stellar gem and pass on the story of Arcturus as we all learn more about our wonderful universe on story at a time!
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