Skywatch: Little crown of night sky may pop a new star this summer

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Corona Borealis, a Latin name that translates to “Northern Crown,” has always been one of my favorite constellations. It’s small but distinct and bright enough to see even moderately light-polluted skies. This time of year, as evening twilight ends, it puts on a great show nearly overhead in the very high southeastern sky. Sometime this summer, though, it could really surprise us with a new star … more on that in a bit.

(Mike Lynch)

Corona Borealis, the little crown of stars, is not alone in the night sky. It hangs to the lower left of a much larger constellation, Bootes the Herdsman, which resembles a giant celestial kite flying diagonally above.  The tail of this celestial kite is marked by the very bright star Arcturus, which is also the brightest star in the evening sky in late spring and summer. Even with the naked eye, Arcturus stands out with its distinctive orange hue, shining at us from about 215 trillion miles away.

This time of year, it resembles a sideways letter C. However, with just a touch of imagination, Corona Borealis reveals its beauty, a crown or a tiara, a celestial adornment fit for a beauty queen like Miss America. In Australia, it’s seen as a boomerang, and you certainly see why. Admittedly, Corona Borealis may not be a constellation that astronomers get overly excited about. There’s not much to see within its boundaries with a telescope, even a larger one. It lacks prominent star clusters, nebulae or galaxies. In fact, many amateur astronomers affectionately refer to it as “Core Bore.”

The brightest star in the Northern Crown is Alphecca, pronounced al-feck-ah, a hot bluish-white star about 75 light-years away. The light we see from Alphecca tonight left that star in 1949 when the average price of gas in the United States was 17 cents a gallon.  Like many stars, Alphecca is an Arabic name that roughly translates to English as “broken,” referring to the fact that it’s the bright star in a broken ring of stars, which is what Corona Borealis truly is since it’s only a half-ring of stars.

(Mike Lynch)

Just off the lower left of the left side of the sideways C is an extremely faint star, T-Coronae Borealis. There’s no way you can see that star with the naked eye. You’ll have a moderately large telescope, but even then, it’s extremely difficult to find. So why am I bringing it up? Because there is a decent chance that it’ll suddenly dramatically brighten into a new naked star, at least temporarily. T-Coronae Borealis is also known as the “Blaze Star,” but it sure doesn’t blaze that often. In the last 150 years, it’s only blazed up for a few days back in 1866 and again in 1946, but many astronomers predict it could blaze again sometime this summer, give or take.

So, what’s going on? T-Coronae Borealis, about 3,000 light-years away, is a double star system comprising a large red giant star and a dying white dwarf star. As the two orbit each other, the intense gravity of the white dwarf pulls gas off the red giant star. The details are complicated, but the white dwarf star can only acquire so much additional gas before it becomes extremely unstable and ignites in a brief flash of nuclear fusion on its surface, triggering what is known as a nova outburst. When this happens to T-Coronae Borealis it temporarily becomes as bright as Alphecca and also as bright as nearby Polaris, the North Star. In about a week, though, T-Coronae Borealis fades back to obscurity.

Keep your eyes on Corona Borealis. The Northern Crown might soon process another jewel when the Blaze Star blazes away!

Celestial happening this week

This coming Friday morning during early morning twilight, the last quarter crescent moon will be parked just to the lower left of the planet Saturn. Even with a small telescope, you should be able to make out Saturn’s ring system. Off to the far lower left, near the horizon, is the much fainter planet Mars.

Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and Mike is available for private star parties. You can contact him at

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