BAN #245: No impact for asteroid 2020 NK1, Red dwarfs are babies, The Last Stargazers

17 August 2020   Issue #245

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

Subscribers have a positive impact, unlike a support cable or an asteroid.

Random Thoughts

Stuff I think about in the shower, typically

The lowest-mass red dwarf stars have a lifespan of roughly a trillion years (maybe longer).

The Universe is 13.8 billion years old.

Scaling a red dwarf’s lifespan to that of a human, any of these ultra-low-mass red dwarfs fusing hydrogen into helium right now is the equivalent of a 1-year old baby.

Just thought you’d like to know.

[Artwork depicting the red dwarf DG Cvn, which commonly flares enthusiastically. Credit: NASA GSFC /S. Wiessinger]

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.

Hey, some good news: The asteroid 2020 NK1 now has no chance of hitting the Earth for the foreseeable future.


You may not have heard of it — I missed it too — but for a short time this rock had a non-zero chance of hitting us starting in 2086. It was discovered in July, and the calculated orbit took it pretty close to ours, enough to be worrisome. But more observations yielded a more accurate orbit, and showed there’s no threat of impact now.

One of those observations was by the Arecibo radio telescope in Puerto Rico. It can send radar pings to the asteroid, which bounce back and give astronomers info about its size and exact distance, which can be used to nail down the orbit. Good thing it’ll miss: Those observations showed it’s about a kilometer long, which would make quite the impact. Yikes.

[Radar image of the asteroid 2020 NK1, from the Arecibo radio telescope. Credit: Arecibo Observatory / NASA / NSF / UCF]

People like to blame everything on 2020. But this rock even has that number in its name, and it’ll miss. So much for superstition!

… on the other hand, after I drafted this article some news came out that a cable snapped on the Arecibo telescope, damaging the dish.

[Part of the Arecibo radio telescope suffered damage after a cable snapped. Credit: UCF]

Well, that sucks. The Gregorian Dome was damaged as well; that’s the weird polyhedral enclosure that houses reflectors that help focus radio waves.

I don’t know how long it will take to make the repairs… plus they’ll have to inspect the whole structure to look for issues, and it’s a very, very big dish, over 300 meters across. It may be a while before we see any observations from it again.

If I hear more, I’ll let y’all know.

[PlanetLabs SkySat satellite image of the Arecibo radio telescope taken on 10 August 2020. The damage can be seen to the left of center of the dish. Credit: PlanetLabs]

P.S. By the way, the European Space Agency puts out a monthly Near-Earth Object newsletter, and this one is mentioned in the 2020 August issue. I just signed up for it, and hopefully the asteroid news will continue to be good.

Book ’em

Sometimes I read books

I recently had the pleasure of talking with my pal and astronomy/scicomm colleague Emily Levesque about her new book, “The Last Stargazers”, in a virtual interview sponsored by my favorite bookstore in Denver, Tattered Cover. The book is full of wonderful, amusing, and sometimes scary stories about that peculiar breed of scientist, the observational astronomer.

Of which I am one. During the interview we talked about a few of the weirder tales, including observatories that have been damaged by natural disaster, time, and once by, um, gunfire. Yes, seriously. Here’s the recorded stream:

“The Last Stargazers” was a lot of fun to read. I know, I’m biased, because I’ve been to some of those observatories she describes, and know quite a few of the characters she writes about. But still, she’s an excellent writer, making the stories charming and, above all, human. I think if you listen to her talk in the stream above you’ll get that idea. She’s a fun person, and the book is totally engaging. Go buy it.

And how timely: Emily recently published a paper about Betelgeuse, showing it dimmed in late 2019/early 2020 due to expelling a dust cloud, and not due to starspots, a conclusion that was recently heavily supported by Hubble observations.

My thanks to Tattered Cover for sponsoring the interview, and to Emily for asking me to be a part of it!

Blog Jam

What I’ve recently written on the blog, ICYMI

[I LOVE this artwork depicting Betelgeuse erupting out a vast cloud of dust. From Friday’s article. Credit: ESO, ESA/Hubble, M. Kornmesser]

Monday 3 August, 2020: When the supermassive black hole's away, the stars will play

Tuesday 4 August, 2020:

The sky is falling! Here's how to watch tonight's Perseid meteor shower

Wednesday 5 August, 2020: The Phoenix star stream, remnant of a long-dead stellar city

Thursday 6 August 2020: How to make a blazar: Slam two galaxies together and watch them feed a huge black hole

Friday 7 August, 2020: Smoking gun at Betelgeuse: Hubble shows it was belching dust that dimmed the red supergiant

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!