Astronomers Think They Know Why Betelgeuse Got Dimmer

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Betelgeuse stopped dimming in the middle of February, and now some of the first papers studying the anomalous brightness variation are starting to appear. It doesn’t look like the star got cooler, there wasn’t a giant starspot that lowered the output, and there wasn’t a cloud of gas in the way. Instead it seems like dust is likely to be the culprit.

We have some great images by the star using the SPHERE instrument at ESO, taken by Miguel Montargès showing a darker area on the star, this shows that the dimming wasn’t a global event.
There’s another image from December showing the dust environment further out from the star taken by Pierre Kervell using the VISIR instrument.

However the most interesting evidence is comes from a team who did spectroscopy, trying to figure out if the star had god cooler.
I want to cover this paper by Emily M. Levesque & Philip Massey
“Betelgeuse Just Isn’t That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse”
Because it offers a good explanation of how astronomers have to go about finding the temperature of stars and because Emily wrote an excellent Twitter thread explaining their process

  1. Chris Antoniou

    Great explanation and answered the questions I had when Betelgeuse started dimming. If this is indeed what has happened on Betelgeuse, it doesn’t mean it won’t go supernova in the short term, only that there is no evidence that it will. As for me, I signed up to get early warning of any large influx of neutrinos and Beterlgeuse is the first place I’d look.
    One thing though, the singular of spectra is spectrum…

  2. Kep

    It’s always dust clouds :(

  3. Rick Karrer

    Great video, thank you!

  4. IvelLeCog

    Scott, can you do a video on micronova events?

  5. Curator on the internet.

    A planet from the far outskirts of the system? Torn apart by expansion ?

  6. Shane Lylick

    Was this the same star that was speculated to have a Dyson sphere around it

  7. Gribbo9999

    Thanks Scott. Can always get some good science on your channel!

  8. Tom Veatch

    Another “Tabby’s Star”?

  9. Benson

    Congrats on 1 million subs!

  10. Safe Space Bear

    Clouds? I know the sun’s brightness often suffers bc of them….

  11. ravneiv

    Pretty interesting the 3 stars making the belt of Orion are still close to being in a line at Betelgeuse

  12. Hiroshi loves You

    Yay my favourite star is regaining it’s strength! 💛

  13. Vox Deus

    Yup, I was out tonight, and it is a good bit brighter now.


    “Giant dust” … but … dust is … fine ? lol

  15. MalfunctionM1Ke

    Thanks for keeping us on track on the topic, Scott

  16. z beeblebrox

    Imagine being in orbit around Betelgeuse, with how intensely its atmosphere shifts in elevation. I’d be pretty wild to wake up every morning to a wobbly sun

  17. Shermanofyaxley

    Looks like a micro nova to me. In the coming years we will see the dust clouds expand further out as the star gets brighter again.

  18. L Dewey

    Thanks for the fascinating explanation!

  19. David Hall

    An excellent summary, thank you Scott! I spent a summer helping a prof study a bunch of M-class spectra, and those TiO2 lines bring back long forgotten memories…

  20. sulijoo

    Betelguese got dimmer because it was watching Star Trek Picard.

  21. Nitz

    Scott, I’ve been a long time viewer and I was wondering, when will you be doing another KSP series?

  22. etherealessence

    Don’t care what you told us, you’ll never kill the hope in our hearts ;)

  23. Brtree74

    Great video. Very well explained and communicated. Thanks for this.

  24. hellcat1988

    SO I was kind of right in a previous video comment that it was matter getting thrown off. Cool.

  25. AngleSideSideThm

    Congrats on 1 million subscribers!

  26. xavierjaquet95

    when you were saying Betelgeuse I ear beetle-juice

  27. Lemon Lady

    We’ve heard all the experts now. I think we need to hear from Michael Keaton (the original and iconic Betelgeuse in the original movie) on this matter. Just to lighten things up…

  28. MrGonzonator

    Damn, that cut at 2:29 was a bit sharp. Eyes were fully dark adjusted and bam!

  29. Daniel Kintigh

    Thank you for this video!

  30. tehbonehead

    Star dust?
    Ziggy Stardust!

  31. Blue LeStrange

    She looked a bit brighter last night around 3 am I noticed

  32. Arctic Haze

    Very interesting. Also to a viewer with physics background!

  33. Marlin Müller

    Love those paper reviews…. Wizkd be interested in more stuf like that

  34. Sean McDonough

    3:31 – I dunno, looks pretty easy to me if you ignore the distracting spikes…

  35. Patrick VDL

    I was really surprised by the use non SI units like ergs and ängstroms in a modern paper. Is this standard practice?

  36. Jason Mueller

    Jeb, I’m leaving you in the ocean.

  37. Gidagorfen

    `Maybe it had CORONAvirus….

  38. Alex M

    What softwares does Scott uses in this video?
    … I mean, this one: 0:10

  39. Porkchop Sandwiches

    I was looking at it awhile ago and was wondering why it was so dim…
    I guess it wasn’t just me.

  40. Gerry Larsson

    Thanks, Scott. I love your channel and the responsiveness of your videos. Any time I hear/read about some phenomenon happening out in space I can always count on you to explain it with the least biased information. Much appreciated.

  41. OFGW

    Mr. Scott Manley, thank you so much for this video, in fact thank you for all your content. I always learn so much from you.

  42. SuperDave

    So…in layman’s terms, Betelgeuse farted?

  43. Nicholas Maude

    I hope that Alpha Orionis goes boom during my life as I want to see a supernova with my on eyes.

  44. liquidbraino

    (On the cosmic scale, it takes a few minutes).

  45. Kevin Street

    Thank you for this video! That explanation is really interesting.

  46. Quinton Murdock

    Yay. Zaphods home lives again

  47. Steve the Pirate

    I taught the other smokers at work where Betelgeuse was then reassured them it wasn’t going to explode any time soon thanks to Youtube.
    We’re mechanics.

  48. El Guiñolo

    Say “Betelgeuse !” three times and you’ll see why it’s getting dimmer.

  49. Penny Lane

    Giant Dust is what my D&D group had to get from the Swamp of Terror to craft a Belt of Giant Strength recently.

  50. dreedee

    omg, wasnt just me or when stearing ta the IR image with the dark circle on the centre it felt like all the surrounimnds was moving? I even had to pause the video to check! BetleGeuse-zary

  51. Milutzu K

    This is exactly what I was expecting for quite some time: a spectrophotometric evaluation of dimming of Betelgeuse. Thank you very much!

  52. Sebastian Schneider

    When astronomers are speaking of “giant dust particles” am I right to assume planet-sized fluff?

  53. Anton Ekermans

    “… trying to figure out if the star had god cooler.”
    So an act of God? :)
    Thanks for the info, I suspected as much (dust).

  54. Andres Morilla

    Great as always, thanks for bring this information to the masses, well explained and with images!

  55. SkaterSurfer Snowboarder

    so in a way, its from:
    Star Farts? 😂

  56. Tuzon Thume

    I’m having trouble grasping the probable size of the ‘dust’ that could dim a red giant. Unless there is a dust stream directly at the observer.

  57. FHM Consulting

    I was waiting for the eyelid to open in that animation…

  58. Bartosz Kruszona

    “Betelgeuse isn’t that cool”


    “I told you so” Yeah huh it could have exploded 600 years ago / you don’t know.

  60. GENeric08

    Could it be the largest CME we’ve ever seen?

  61. PercivalBlakeney

    No chance someone could come up with a portrait of Orion with the face of Michael Keaton?
    It’d be kind of funny if nothing else. 😌

  62. Ronald West

    I wish I could speak Scotch as good as this guy.
    It reminds me of my younger days when my great grandmother spoke fluent Scotch, especially when she was pissed at me.

  63. Billy Sugger

    Scott, one spectrum, two spectra. 👍

  64. antisteo

    It’s a Dyson Sphere

  65. Atrahasis7

    “Zorg cut it out”, ” I just wanted to make a dog shaped shadow for earthlings we planted millions of years ago, I also know how to make and old guy chew”.

  66. NPC #1656

    “Why did Betelgeuse get dimmer?”
    It got a bit dirty

  67. dan k

    We’re all gutted let’s be honest we all wanted to see that star pop

  68. MrLastlived

    Betelgeuse: I’m back from my break

  69. Regulator Machine

    5:47 so now you understand that…. actually yes, now I do, thanks again !!! awesome content as usual!

  70. Spanos

    Everyone knows that the brood queen Z’viex, long may she reign, needed to power her hyperia gates to transport her drones to catch the Zarkit alliance in the rear. Her mission accomplished, she doesn’t need to drain the star any further. Unfortunately her fleets were defeated by Xen Therix and his ragtag group of rebels.

  71. Darren Brashaw

    Maybe it just needed another 50p in the meter!

  72. Ricardo Becerra

    The last famous last words! …. “I told you so.”

  73. Dark Knighte Apologeticz

    Yayness, Betelgeuse didn’t go boom. Wait a minute, drat I wanted it go boom. lol

  74. Caonabo Javier

    Scott: Great video. Again, you should be teaching university clasees! You explain everyrhing so well ans deep, yer so easy to understand. Thank you.

  75. Nan Ma

    “I was never a stellar astronomer”. Oh, you are stellar.

  76. rtrThanos Ezekyle Abaddon

    Imagine my surprise when I expected to hear Anton say “Hello wonderful person” and was instead greeted by “Hullo, it’s Scott Manly here.” Clearly I was NOT flying safe.

  77. Ben Sheaves

    5:20 ah yes astronomy were ergs are used to measure energy and apparently wave lengths are measured in angstroms. As a chemist the later confuses me

  78. Anarchy Antz

    Scientist: Betelgeuse isn’t cool any more!
    Betelgeuse : I thought we were friends man! *sits in the corner and cries at no longer being the cool star in the galaxy*

  79. Kingdom of Hush

    “Now that you understand that….”
    Sir I don’t understand that… Lol

  80. Jarren Carroll

    “Halloween Scott Manley here…”
    AutoCaptions can never get your intro right haha.

  81. Neth

    4:17 So it’s actually Bob Ross causing the dimming with his Titanium White

  82. Joseph Clark

    That time lapse with the convection movement etc, looked extremely cool imo

  83. thom1218

    @4:10 “Titanium oxide is a really good absorber of lots of colors” – I’d say it’s a good reflector of lots of colors, i.e. it’s white.

  84. Brent Geery

    I’m still amazed we can take pictures of stellar and planetary disks!

  85. Vasile Sulica

    It’s gonna explode eventually, that type of star always does and only then “I told you” would be appropriate.

  86. Kineth1

    I like this version of the thumbnail caption better:
    “Are giant dust grains behind the dimming of Betelgeuse? No, they’re in-front of it!”

  87. Johnny Appleseed

    Betelgeuse dimmed because everyone was staring at it… Remember, everyone wants to be noticed but nobody wants to be stared at…

  88. Azog


  89. HuntingTarg

    Scott, you did great. I’ve been watching space & rocket news for going on three decades:
    You’re a dj/gamer/programmer/amateur astronomer/amateur astrophysicist/(semi-)amateur space news reporter.
    You’re one of the best YouTubers uploading today imo.
    Fly safe, keep on keepin’ on 🖖😎✌

  90. ss

    Betelgeuse: “Sorry Folks I Caught A Cold, I’m Better Now”

  91. Sam Sneddon

    Things that make stellar physics fun: “as the temperature drops to around 3500K”.

  92. drakazabijaka

    “Betelgeuse just isn’t that cool” whoa, chill guys..

  93. Streamer Guy

    I really wanted to see a supernova in my lifetime!!!!!

  94. Kens Garage

    this happened 642 years ago >.>

  95. Jason Du Ban

    *John Cleese peasant voice* “I got better…”

  96. jnelchef

    I got everything except the part after “Hello, it’s Scott Manley here…” could you go over that again, please?

  97. foxpup

    The darkening was caused by the massive Orion Battlefleet on its way here from Betelgeuse, blocking out part of its light. They noticed they were causeing a shadow and shifted a bit to prevent that in the future or at least until it’s too late. :-)

  98. Jack Linde

    Betelgeuse : “I’m not getting dimmer. You’re getting dimmer. And I’m not crying over the mean comments you’re saying; ‘hoping I explode soon’. It’s just dust in my eye.” (Someone needs a hug.)

  99. Hobo Sullivan

    Fine video, as always. But I’m not going to sit here and pretend I wasn’t hoping for a nearby supernova in my lifetime…

  100. moocowpong1

    9:00 : “I was never a stellar astronomer…”
    Don’t be so hard on yourself, I’m sure you were a great astronomer!

Comments are closed.