When most stargazers think of famous constellations with recognizable patterns, Orion, Ursa Major, and Scorpius often come to mind. Yet nestled between Boötes and Hercules is one of the sky's most elegant formations: Corona Borealis, the Northern Crown. With its unmistakable C-shaped pattern, it is hard to miss. In this blog, we will dive into the stories behind this celestial coronet, examine its brightest stars, and learn about the celestial objects that make this constellation a crown jewel of the summer sky.
The Legend Behind the Crown
In Greek mythology, Corona Borealis, the Northern Crown, represents the golden crown of Princess Ariadne, daughter of King Minos of Crete. According to legend, Ariadne helped the hero Theseus navigate the Labyrinth maze and escape after he slew the Minotaur, a fearsome creature with the body of a man and the head of a bull. After Theseus abandoned her on the island of Naxos, the god Dionysus fell in love with Ariadne and presented her with a magnificent golden crown as a wedding gift. Following her death, Dionysus placed the crown among the stars, where it shines eternally as the constellation Corona Borealis. Its distinctive C-shaped semicircular arc of stars symbolizes Ariadne's jeweled crown, making it one of the most recognizable constellations in Greek mythology.
How to Find Corona Borealis
In the Northern Hemisphere, Corona Borealis is easy to spot during late spring and summer evenings, when it appears high in the night sky between the constellations Boötes and Hercules. A helpful way to locate it is by first finding the bright orange star Arcturus in Boötes. Just beyond Arcturus, you will notice a semicircle of stars that forms the unmistakable shape of a crown. Once you recognize its shape, Corona Borealis becomes one of the easiest constellations to identify.
Notable Stars in Corona Borealis
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Alphecca (Alpha Coronae Borealis)
The brightest star in Corona Borealis is Alphecca, also known as Gemma, which means “the jewel.” This striking star is an eclipsing binary system, composed of two stars, a bright white star and a smaller yellow companion star, orbiting one another. Located about 75 light-years from Earth and shining at an apparent magnitude of +2.2, Alphecca forms the sparkling centerpiece of the Northern Crown and is easily visible to the naked eye on clear nights. Its brilliant glow makes it one of the most beautiful stars in this region of the sky. -
T Coronae Borealis: The Blaze Star
Astronomers are closely monitoring T Coronae Borealis (T CrB), a recurrent nova known as the "Blaze Star” located just outside the crown. It is expected to erupt and become visible to the naked eye for the first time since its last outburst in 1946. Located approximately 3,000 light-years from Earth and currently shining at about magnitude +10.2, T CrB is a binary star system consisting of a white dwarf and a red giant. In time, material from the red giant accumulates on the white dwarf until a thermonuclear eruption occurs, causing the system to brighten dramatically.
Although the event has yet to occur, when the nova finally erupts, it may brighten from about magnitude +10 to +2, the same brightness as Polaris, making it visible to the naked eye and creating the appearance of a new star in the night sky for several days. Until then, skywatchers will need to continue monitoring the constellation and hope to witness history. -
R Coronae Borealis
R Coronae Borealis (R CrB) is a rare yellow supergiant located about 4,000 light-years from Earth. It is known as a "reverse nova" because it behaves in the opposite way of an exploding star. Instead of suddenly brightening, it unexpectedly fades from view.
Normally, R CrB shines steadily and is visible through binoculars or a small telescope under dark skies. Every few years, however, it releases a large cloud of carbon-rich gas. As the gas moves away from the star, it cools into dense carbon dust, forming a broad cloud of cosmic soot. When this cloud passes between R CrB and Earth, it blocks the star’s visible light, causing the star to dim dramatically or even vanish from view.
Over time, radiation pressure from the star pushes the dust cloud farther into space. As dust disperses, the star slowly returns to its normal brightness, a process that can take several months or even years. The result is one of the most unusual cycles in the night sky.
Deep-Sky Objects
Corona Borealis is not known for bright, easily observed deep-sky objects. I[KK6.1]t serves as a gateway to the distant universe. Among its notable sights is the galaxy cluster Abell 2065, a massive collection of more than 400 galaxies located a billion light-years away. The constellation also contains NGC 6086, a giant elliptical galaxy about 462 million light-years away. For most backyard stargazers, however, these galaxies are too faint to reveal much detail and often appear as little more than dim smudges of light. As a result, many observers find the constellation’s variable stars and distinctive crown-shaped outline to be its most rewarding features.
Observing Tips
- Use binoculars to appreciate the constellation's picturesque C-shaped crown of stars.
- A small telescope can reveal subtle color differences among its stars and several attractive double-star systems.
- Observing from a dark-sky location will make it easier to see the constellation's fainter stars.
- Look for Corona Borealis on late spring and summer evenings, when it climbs highest above the horizon and offers its best views.
A Crown Worth Discovering
Corona Borealis may not be the largest constellation, but its delicate arc of stars, fascinating mythology, and intriguing stellar inhabitants make it one of the season's most rewarding sights. From the sparkling brilliance of Alphecca and the unpredictable Blaze Star to the unusual "reverse nova" R Coronae Borealis and the distant galaxy systems hidden beyond its stars, the Northern Crown offers something for observers of every experience level.
The next time you find yourself gazing upward on a warm summer night, look between Boötes and Hercules for the arc of stars that forms Corona Borealis. Whether you are tracing the outline of an ancient celestial crown, following the story of a star on the verge of eruption, or simply admiring its stellar beauty, you may discover that this small constellation is well worth exploring.
Clear skies and happy observing!