Starry Night Spotlight #1 Betelgeuse

Francis Kuklis

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Have you ever looked up at the stars on a clear night and felt awestruck, as if you are seeing the night sky for the first time? The universe is incredible and vast, and we are learning new, fascinating things every day about the space around our Pale Blue Dot. We are in the golden age of astronomy. I invite you to take a journey with me to explore a little piece of the heavens to learn more about our place in the universe.

Orion the Hunter is one of the most notable constellations in the night sky. Even young children can point out the Big Dipper, and the three stars that comprise Orion’s Belt. While these three stars are the most notable in Orion, the variably brightest star in the constellation is named Betelgeuse. The term variable is used because Betelgeuse tends to brighten and dim in cycles, with observations going back to the time of Ptolemy in ancient Egypt.  In recent years Betelgeuse has moved between being the sixth and seventh brightest star in the night sky. At least it was until the end of 2019. In the last few months, this red supergiant star has dimmed by over 25%. A star as bright and close to Earth as Betelgeuse to dim so significantly and quickly is a puzzling phenomenon.

Stars that are classified as red supergiants are massive and need a lot of energy to sustain them. Because of their gargantuan size, Betelgeuse undergoes the process of fusion fairly rapidly and while the star is less than 10 million years old, astronomers are fairly certain that in less than 100,000 years there will be a tragic end to the supergiant star. As these nuclear fusion powerhouses continue to combine hydrogen molecules into helium, then produce heavier elements, the process of fusion slows down and eventually, the star becomes unstable. This results in a galactic-scale nuclear explosion known as a supernova.

So, why is this big news? Let’s look back at Betelgeuse dimming so quickly. As red supergiant stars slow down the fusion process, it’s like turning off the lights. Some astronomers believe that this abrupt decrease in luminosity is a sign of the times for this bright red star. If Betelgeuse is dying, the dimming is an indicator, and while we don’t have enough information to say for sure, a supernova visible to us here on Earth would be one of the most fascinating observable events in the modern era. Betelgeuse is approximately 650 light years from our Sun, and its supernova would be brighter than a full moon, and visible at all hours from a few weeks to three months. In fact, studies suggest this phenomenon could be bright enough to cast shadows during the night!

Astronomers are not in agreeance that Betelgeuse is nearing its death throes, and so the debate is on about what this dimming of the star could be. As mentioned before, there are well documented times throughout history where the star has gotten brighter or dimmer, and yet still shines today. But just in case, when the night sky is clear, look up to the north-northeast and spot the three blue stars of similar brightness of Orion’s Belt. Then look just above them and left, and you should spot a noticeably red star. That is Betelgeuse. Take a moment to appreciate the view of Orion the Hunter, because tomorrow, the constellation as we know it could be gone forever.

Francis Kuklis
The constellation Orion imaged on 22 November 2019 with Betelgeuse pointed out. This image was taken at Pulpit Rock just east of Hamburg, Pennsylvania.

Francis Kuklis
The constellation Orion imaged on 21 December 2019 with Betelgeuse pointed out. This image was taken north of the Arctic Circle near the Yukon River Camp, Alaska.

Francis Kuklis
The constellation Orion imaged on 24 January 2020 with Betelgeuse pointed out. This image was taken at Bake Oven Knob north of Germansville, Pennsylvania.