BAN #183: Navel defeat, Banner day

13 January 2020   Issue #183

[Spiral Galaxy M81 image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona]

Subscribers are the red supergiants of newsletter readers.


You can’t debunk something unless it’s bunk to start with

As you certainly know by now, for the past few weeks Betelgeuse has been up to some shenanigans, dimming considerably. This is something it does fairly often, though this current episode is a particularly deep dip.

I’ve been getting a lot of email about it, as you might expect, but this one was unusual.

Sorry to bother you, this may be a question for a medical doctor rather than an astronomical one. I just read on an astrological site that Betelgeuse rules the navel in the human body. If it were to supernova tomorrow, what should I expect from my now leaderless belly button? Will another star step in to quell navel anarchy across the globe? 

He had me going for the first couple of lines! After I finished laughing, I checked out the website he mentioned. Called Astrology King, it’s the usual sort of word salad that astrology sites excel in. Stuff that kinda sorta sounds meaningful but when you really look at it you realize it’s all vague handwavy stuff.

[Betelgeuse on 20 Dec. 2019, taken using my Google Pixel 2 XL phone on Night Sight mode. Usually it’s nearly as bright as Rigel (the brighter star to the right) but it has dimmed a lot recently. Credit: Phil Plait]

But the Betelgeuse page really had me banging my head against my desk. As advertised:

“Betelgeuse star rules the navel in the human body.”

Huh. As you may or may not know, Betelgeuse is part of Orion’s upraised right arm (he is facing us so we see it on the left). Which part of his arm, though? Well, the name is derived from the Arabic Ibṭ al-Jauzā’. And what does this mean?

Literally, “the armpit of Orion”.

So the next time someone tries to sell you on astrology, you can look ‘em right in the eye and say, “Astrologers don’t know their belly button from their armpit.”

Tip o’ the 13th zodiacal constellation to Chris Fitzgerald, who polluted my brain with this knowledge.

Astro Tidbit

A brief synopsis of some interesting astronomy/science news that may be too short for the blog, too long for Twitter, but just right (and cool enough to talk about) for here.

[Note: For completeness, this section could also be “About this newsletter”.]

As you may have noticed, I changed the banner image for the newsletter. I’ve done this a couple of times now; the first was after 100 issues (going from a Hubble image of the globular cluster Omega Centuari to a Cassini image of Saturn), and a couple of other times for special occasions (a short story I wrote about Mars, and for Earth Day).

But with a new year and new decade, I figure why not? So I changed it again, this time to a gorgeous image of the nearby spiral galaxy M81, taken by my friend Adam Block. Adam is an astronomer and extremely talented astrophotographer; but he has the distinct advantage of having access to larger telescopes, so his shots usually show what we call “deep sky objects”: nebulae, clusters, galaxies… and if his name is familiar it may be because I’ve featured his work in the newsletter many times (like with the Pleiades, the Horsehead Nebula, Rho Ophiuchi, R Aquarii, the North America Nebula, and the spiral galaxy NGC 2997). I can’t even count how many times his photos have graced my blog.

I wanted a spiral galaxy this time, for no reason other than I like them. I wanted it to be at a decent inclination angle — the angle it’s tipped toward us — since the banner is square, and a more open view of spiral arms fits well in that sort of boundary. I also wanted to use something by Adam specifically, so I went to his site and poked around. When I saw M81 I knew I had a winner.

This galaxy is located about 12 million light years away, making it one of the closest big spirals to us. It’s the biggest member of a small group of a few dozen galaxies called — can you guess? — the M81 Group. That includes M82, a smaller galaxy undergoing a violent episode of star birth, making it one of the most photogenic galaxies in the sky… a tough role, given that it’s right next to M81!

In fact, both can be seen together in a small telescope using a low-power eyepiece. I’ve seen them myself with my own ‘scope! There was a supernova in M82 (pardon the goofed-up formatting in that post; I’m working on fixing errors that occurred when the blog was migrated to SYFY) at the time, which we could just barely see, but that was one of the very few times I’ve seen such an object with my own eyes; honestly that’s another reason I picked M81 for the banner. Those two together have a personal connection.

As far as I know, M81 is a rather typical spiral galaxy, with gorgeous arms busily making stars (much easier to see in the infrared!) A cursory literature search doesn’t turn up too much about it to make it stand out against the thousands of other spiral galaxies in the sky you can easily see… except that it’s close and tipped enough that we get an overall view of its structure.

And that is precisely why it’s so spectacularly gorgeous, and in the end that’s why I chose it. I think that’s a perfectly legitimate reason.

Blog Jam

What I’ve recently written on the blog, ICYMI

[A truly stunning Hubble image of UGC 2885, a truly huge galaxy. From Thursday’s article. Credit: NASA, ESA, and B. Holwerda (University of Louisville)]

Monday 06 January, 2019:Are volcanoes on Venus erupting right now? Like literally, *right now*?

Tuesday 07 January, 2019:The care and feeding of baby supermassive black holes

Wednesday 08 January, 2019:Dwarf galaxies have supermassive black holes, too… and some are off-center!

Thursday 09 January, 2019:Hubble's spectacular view of UGC 2885: Is this the biggest spiral galaxy in the Universe?

Friday 10 January, 2019:Meet 2020 AV2, the first asteroid found that stays in side Venus’s orbit!

Et alia

You can email me at (though replies can take a while), and all my social media outlets are gathered together at Also, if you don’t already, please subscribe to this newsletter! And feel free to tell a friend or nine, too. Thanks!