Betelgeuse Dims in Orion

The star Betelgeuse has been in the news since December 2019. It is called a Red Giant due to its color and size. It is the upper left shoulder of Orion seen in this chart from Wikipedia Commons.

Orion_constellation_map.png: Torsten Bronger

It has a slight reddish hue visually and a diameter estimated to be nearly as large as the orbit of Jupiter. Betelgeuse is a variable star meaning its brightness changes over time. The time period is quite long on the order of 2000 days. In December 2019, variable star observers reported it had rapidly reached its lowest level ever observed. Speculation is widespread over whether it will soon become a Supernova. More on that later.

Best Comparison

Betelgeuse is compared here between Feb 2016 on left and 31 Dec 2019 on right. The background stars are adjusted to be of equal brightness showing Betelgeuse dimmer today. Compliments to Dr. Brian Ottum of New Mexico for this image comparison.

Brian Ottum – New Mexico

A Test For You

Over the years I have photographed the Orion constellation many times using different cameras, settings, and sky conditions. I gathered six of those images here. One of them was taken the night of 5 January 2020. Can you tell which one? All images have been rotated to orient them the same for easy comparison. Compare the relative brightness of Betelgeuse to the other stars. See if you can tell which image shows Betelgeuse dimmer than normal. Put your letter choice in a comment. Click images for better detail.

What If It Went Supernova?

No one knows if and when that might occur. If it did, Betelgeuse would put on a spectacular display. Estimates tell us it would rival a full moon in brightness, easily casting shadows at night. It would be visible in the daytime for several weeks. A growing cloud of gas and dust would spread from it as in this example. This image was from an excellent article by NASA about Supernova 1987a.

X-ray: NASA/CXC/PSU/S.Park & D.Burrows.; Optical: NASA/STScI/CfA/P.Challis

Size Comparisons

Space is big. It is hard for our minds to comprehend the sizes and scales of it and the objects scattered throughout. This graphic helps to put several of those objects into perspective.

19 thoughts on “Betelgeuse Dims in Orion

    • My eyes could tell pretty easily it was dimmer than I remembered.

      Thanks for your pick. I will wait a while to see if there are others and concensus.

      • Same here. It was so dim a couple of weeks ago, that I thought I assumed I was seeing things… or it was clouds… or light pollution… or I was very, very sick. 🙂 It’s strange to see.

        • It is helpful to have personal history of looking at the sky. That way we can tell if something appears different. I am afraid few people have that history today for a variety of reasons.

  1. Not sure which 1 is dimmest – possibly B. Orion is one of the relatively few constellations I can readily identify. I wonder what other names have been given to that region of stars. For early cultures without written records we may never know.

  2. Betelgeuse seems at it’s brightest in image A but it’s hard to tell which of the other five is the dimmest.

    The best way is to compare it with another nearby star. I used Bellatrix and it seemed to me that Betelgeuse is dimmest is in image C.

    However, having done that, I noticed that Bellatrix is variable too…..

    I’d love to see a nearby supernova in my lifetime but I’m not sure if I want it to be Betelgeuse, such a significant member of the most recognised constellation.

    My understanding is that Betelgeuse is still fusing Helium into carbon and oxygen. If it goes supernova at the end of that cycle it will become a white dwarf. If it is massive enough to continue fusing even heavier elements, it will most likely become a neutron star.

  3. Wonderful post. I know the answer is E from your reply to comments. Not so easy though. not sure if I would have picked E. I looked at the difference between the brilliance of Betelgeuse and Rigal in your photos. Not sure if I want to see Betelgeuse go supernova quite yet. I’m in love with those winter stars and don’t want them washed out by a full time full moon. Enjoyed the size comparisons. We are certainly a speck. Take care.

    • Thanks. I hope you saw the image added later with a good comparison. I would miss Betelgeuse if it blew up. But it would be a big show.

  4. I have been keeping my eye on Betelgeuse since reading this post! I am glad you putting in that size comparison graphic; it is amazing! I never had a good appreciation for the size differences before.

    • I read today that Betelgeuse continues to slowly dim. I wonder what will happen. I’m guessing it will brighten again with no big change.

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