Fryed astronomy

By Phil Plait | March 2, 2009 10:40 am

Sadly, I cannot embed this video (hey BBC, it’s the 21st century! Hello? Hello? Free publicity here! Sigh.), but it’s worth clicking to see this clip of the brilliant comic (and even better skeptic) Stephen Fry hosting the game-like show "Quite Interesting" — a program where he quizzes comedians over various topics, though it’s really just an excuse to make lots of pretty funny jokes. In this particular clip, he asks the celebrity contestants how many moons the Earth has, and the answer is… well, surprising.

Let me know when you’re done watching, OK? I’ll wait.

Great, finished? Good. Stephen was talking about the asteroid Cruithne (pronounced GORR-bleccchhh), which orbits the Sun on a path very similar to the Earth’s, but slightly more elliptical. Back when the object was first determined to have this odd orbit, I wrote about it on the BA News page. It wasn’t named Cruithne yet, so you won’t see the name there, but the basic idea is how this object is not really a moon of Earth, but not totally independent of us either.

Stephen Fry on QI
"We have late-breaking news…it’s evidently
pronounced Ecky-ecky-ecky-ecky p’kang!
Zroop-boing! mrowvm…"

In fact — and I hate to say this, as I follow Stephen on Twitter (heck, everyone does), I like him very much, and I’m fond of his personal assistant, too — but his information on the show was wrong! There are at least four other objects like this, but in fact none of them is really a moon of the Earth (see item 7 on that list). They aren’t bound to the Earth gravitationally, so they aren’t moons. We don’t really have a name for this type of object, as far as I know — a fact I find interesting, as in general classes of asteroids with similar orbits are typically named after the first one of their kind discovered. Maybe nobody can pronounce Cruithne (it’s actually pronounced GLAVIN-heyhey) so they didn’t want a class named after it. I’ll note, to be fair, that at least one of these objects was discovered after that episode of QI aired, but some were known beforehand. Still and all, the point is that these objects are definitely not moons of the Earth.

Hubble LMC starfield

Also, I can’t leave without pointing out the background image they use in that clip; I recognized it immediately. It’s a Hubble picture, one I’m intimately familiar with (check the Biographies link for that image). I wrote the supplemental essay for that picture, too.

It’s nice to see it unexpectedly like that. I worked so hard on that data I got sick of it — my task was to count the stars in it and get their positions and brightnesses at various wavelengths, and I spent a long time writing buggy code that never quite did the trick — but now I can appreciate the picture for how pretty it is. In fact, I think the image probably did better as just a pretty picture than any impact it had scientifically. Certainly it was seen by more people as a backdrop for QI than read about it in the astronomy journals! And that’s something that is, really, Quite Interesting.

And hey! Pssst. Stephen! If you read this, tweet a link to it and I’ll release you from your coffee-making duties. Ask your PA for details.

Tip o’ the dew shield to Kyle VanderBeek.


Comments (48)

Links to this Post

  1. Zie Cruithne schijnt door de bomenbijAstroblogs | March 2, 2009
  1. PeterC

    This episode is a few years old. In a later series, he asks pretty much the same question again (and the buzzer sounds when the guests fall into the trap), where he confirms that, in fact, there are a lot more objects, so the answer is either one or lots, depending on one’s definition.

    Of course, the answer is really one – as Cruithne and the others are merely sharing Earth’s orbit around the sun, rather than directly orbitting Earth – but it was nice to see the partial correction. Not many series will go back and admit they got something wrong! [Of course, Mythbusters do as well, but what else could you expect from a Close Personal Friend ™?]

  2. Sarcastro

    (it’s actually pronounced GLAVIN-heyhey)

    Astronomy degree from Clown College?

    Hey, don’t knock it. I graduated Magna Cum LADEEEE!

  3. Todd W.

    I believe it is pronounced Krihn-yeh.

  4. Chip

    Steady now! My uncle’s middle name is Cruithne*.

    * (Pronounced of course “Goorungorrblecchh-hey-hey”!)

  5. Dan

    Maybe these satellite-like objects could be called satelloids? We have planetoids and asteroids, and, um, humanoids.

  6. Time to convene another naming panel!

  7. DavidHW

    Nice tip of the hat to the funniest show on television. The interplay between such diverse comedic intellects — esp. the Fry-Davies-Jupitus axis of evil (wit) — is breathtaking to watch.

  8. I only came across this because I have a budding man-crush on Fry. I’ve watched all the Qi clips I can find; curse Netflix for not having the DVDs! I’ve gone through all the video of Hitchens, Randi, Minchin and others, but none are so charming and funny as Mr. Fry. Right now, he’s #1 on my “would like to have a beer with” list.

  9. I couldn’t help but lol a bit whenever I read “it moons the earth”. Maybe that’s just me though, seeing a giant naked ass up in the night sky…

  10. dre

    I thought Rich Hall was dead! Haha! Glad to see him angry about something on TV again. I still have a Sniglets book laying around somewhere…

    Oh, and doesn’t seem like if some folks pronounce the name correctly for a while, it will catch on and then won’t be joked about every time it comes up – even if the pronunciation isn’t perfect. Kreen-ya or Kroo-een-yeh seem to be the pronunciations that come up when I look for the real name. Let’s just say it some and then it won’t be an issue any more. C’mon, everybody say it with me! KROO-EEN-YEH.

    There, now we’ve taken the first step down the long road to ending pronunciation jokes based on this fascinating satelloid.

  11. Chip

    Wikipedia has some nice little orbital animations. Including Cruithne’s weird bean shaped orbit as seen from Earth:

  12. Todd W.

    Looked it up on wikipedia, and my couple classes in Irish paid off, it is pronounced KRIHN-yeh, or for those who know IPA, krIn’-je (roughly…don’t know the codes for the correct characters).

    Now, let’s show some love and respect for the Irish and stop making fun of their names and language.

  13. Nomen Publicus

    In an episode of QI broadcast a couple of weeks ago the subject of astrology came up and Stephen “officially” banned all who believed in astrology from watching the program, forever.

    Fry is a national treasure.

  14. IVAN3MAN

    According to Wikipedia, 3753 Cruithne was discovered on October 10, 1986 (not “199 ****ing 4” nor 1997 as stated on the video) by Duncan Waldron on a photographic plate taken with the UK Schmidt Telescope at Siding Spring Observatory, Coonabarabran, Australia. In fact, it was not until 1997 that its unusual orbit was determined by Paul Wiegert and Kimmo Innanen, working at York University in Toronto, and Seppo Mikkola, working at the University of Turku in Finland.

    Cruithne is in a normal elliptic orbit around the Sun, with an orbital period of 363.99 days. However, because its period of revolution around the Sun is almost exactly equal to that of the Earth, they appear to ‘follow’ each other in their paths around the Sun. This is why Cruithne is sometimes called “Earth’s second moon”. However, it does not orbit the Earth and is not a moon.

    3753 Cruithne

    Current position of 3753 Cruithne
    (Click on image for the JPL/NASA interactive tool).

  15. Andrew

    The subject of Cruithne has come up several times on the QI forums – you can search for it here:

    There is an “official” statement on theie “Qibble” blog – – “When [that] episode of QI was first broadcast, in 2003, QI was one of the very first to bring Cruithne to the public conciousness. In subsequent series, we told of new discoveries – in series two, 2 more “moons” and in series three a further 4 – but by this time we were careful to specify that they were not “moons” as such, but co-orbital bodies that orbited the Sun rather than the Earth … The earth only has one moon. As Alan Davies said, there can only be one moon – that’s why it’s called “The Moon”.”

  16. Al

    In a more recent programme, Fry registered extreme disapproval at a contestant who dared suggest that astrology and Astronomy might be confused… ūüėČ

  17. Parkylondon

    All this talk of the spelling of Cruithne reminds me of the Monty Python sketch where one name is pronounced completly differently viz:

    Specialist: Ah! Mr Luxury Yacht. Do sit down, please.
    Mr Luxury Yacht: Ah, no, no. My name is spelt ‘Luxury Yacht’ but it’s pronounced ‘Throatwobbler Mangrove’.
    Specialist: Well, do sit down then Mr Throatwobbler Mangrove.
    Mr Luxury Yacht: Thank you.

  18. Two things:

    -I’ve always said it as something like “kr-win-ya”. Close enough, I guess.
    -Todd W: Kiss my 1/4 Irish ass. I’ve taken Irish Gaelic in college, and while the orthography eventually begins to make sense, it was clearly created by someone who was entirely too drunk to properly spell Old Irish (a slightly more sensibly spelled language). In fact, out of all the modern Celtic languages, I think Cornish is the only one that has a spelling system that wasn’t designed by an illiterate or a drunkard.

  19. (Re: illiterates: no offense intended to any Cherokee readers. What I should have said was “partial illiterate” — the creators of Manx and Welsh spelling obviously had at least a partial handle on Early Modern and Old English respectively, but not quite enough.)

  20. Matt A

    Just recently (i.e., it’s still available on BBC iPlayer as of this post) they had Ben Miller, one half of comedy team Armstrong & Miller and former student of quantum physics. It was really good. I can’t speak to the accuracy of the scientific content, but seeing anyone with real enthusiasm for real science on TV is always a pleasure. Here’s a link for those interested…

  21. Todd W.

    @Brian X

    Well, part of the problem with written Irish today, is that it represents a language that is still in transition. That makes it rather tough to understand what is going on at first, but once the rules are known, it makes sense, as you say. Granted, when you don’t know the rules, it makes no sense whatsoever. As for Welsh, I haven’t studied it, but they seem to have even more extra letters per word than Irish Gaelic.

  22. Torbjörn Larsson, OM

    with an orbital period of 363.99 days

    Hm. Well, according to the linked Wikipedia article you will have to do a QI type revision of that comment after July 2292 or so, when Earth and Cruithne will engage in some close up interaction and reverse the status of their platonic relationship.

    Btw, what is an orbit that has this type of periodic change of period called?

  23. Winter Solstice Man

    Nothing beats the time Kelly Pickler (a finalist on American Idol) was on So You Think You Are Smarter Than a Fifth Grader? and publicly declared she did not know that France was an actual country. That she says this without too much shame in her voice or attitude is beyond sad.

    Check it out on YouTube, then do not admit to anyone for a while that you are an American.

  24. Winter Solstice Man

    And then of course there is the infamous Miss Teen America who gave that bizarre comment during a pageant on maps and Iraqs and I don’t know what the heck else she was getting at.

    But being a male, I also admit I found myself able to forgive her. :^)

  25. Gareth

    “my task was to count the stars in it and get their positions and brightnesses at various wavelengths, and I spent a long time writing buggy code that never quite did the trick”

    Ah, that takes me back to my uni days. My final year astrophysics project was to look at three plates of little white dots and work out which ones were galaxies clustered around a distant radio galaxy. It’s been over ten years now so I can’t really remember how I did it, but it had something to do with writing similar buggy code to calculate the positions of all of the little dots (stars or galaxies) on each of the images (two narrow band filters and one broad band filter) and comparing them, with all the stars and other galaxies at different redshifts falling along a straight line on the graph, and the galaxies clustered around the radio galaxy as points away from the line. Funnily enough, two other guys doing exactly the same project got completely different results to me…

    I luvs science! :oD

  26. IVAN3MAN

    Torbjörn Larsson:

    Btw, what is an orbit that has this type of periodic change of period called?

    I can’t say for certain, but I have found numerous references to quasi-satellites that have a 1:1 mean-motion resonance which occurs when two bodies, usually a planet and an asteroid, orbit the Sun in equal amounts of time.

  27. Stephen Fry also wrote a very entertaining alternate history novel, Making History. Check it out.

  28. Grand Lunar

    Wouldn’t this technically be a Trojan, after the groups of asteroids that follow Jupiter and a few other planets around?
    Or do Trojans just hang around a particular point in a planet’s orbit?

  29. You can bet your old boots that Cruithne will continue to be pronounced “Kru-ITH-knee” for a long long time in the UK at least – primarily because Stephen Fry said so!

    btw QI is the only weekly TV programme I take the trouble to watch. The recent episode with Bob Bryden and his doppelganger Ben Miller had me in stitches! I won’t spoil it for anyone who hasn’t seen it, but it’s on Youtube so go take a look.

    Elwood (pronounced “~~~!”)

  30. Rob Bryden, not Bob, sorry. And not Brydon either, even though his name is spelled that way on Youtube. Search for “QI Bryden”

  31. Aargh – it ISBrydon – with an o! (probably pronounced “Get my name right you plonker!”)

  32. CR

    Ah, Miss Teen South Carolina… “I personally believe…” and “and, such as…” and “U.S. Americans…” and “the Iraq…” and so on.
    One minute of pure nonsense gold!
    It’s on YouTube, but just as funny is a parody by ‘Miss West Carolina’ who does indeed know that there’s no such place as WEST Carolina. Clever girl; she’s not even American, but had me fooled with the accent and attitude!

    Stephen Fry & Quite Interesting… I’m going now to find as many clips as I can. Looks like a show I’d thoroughly enjoy. Sad to say,though, that I doubt I’ll be throwing any ‘QI’ parties any time soon.

  33. CR

    Matt A…
    Nuts! That clip you linked to is ‘available for UK viewers only…’

  34. IVAN3MAN

    Grand Lunar:

    Wouldn’t this technically be a Trojan, after the groups of asteroids that follow Jupiter and a few other planets around?
    Or do Trojans just hang around a particular point in a planet’s orbit?

    In astronomy, according to Wikipedia, the adjective ‘Trojan’ refers to a minor planet or natural satellite (moon) that shares an orbit with a larger planet or moon, but does not collide with it because it orbits around one of the two Lagrangian points of stability, L4 and L5, which lie 60¬į ahead of and behind the larger body.

    The term originally referred to the Trojan asteroids orbiting around Jupiter’s Lagrangian points. Subsequently objects have been found orbiting the Lagrangian points of Neptune and Mars. In addition, Trojan moons are known to orbit the Lagrangian points of two of Saturn’s mid-sized moons.

  35. quasidog

    Yeah it’s awesome Steven Fry is a skeptic. Maybe he should have been more skeptical.

    I am getting tired of this term.

  36. Matt A

    CR – I’m so sorry… that you have to live in a country that isn’t the UK. :-) Anyway, I consulted the Tubes of You, which is probably what I should have done in the first place, and part one of the show is here

  37. Nigel Depledge

    Grand Lunar said:

    Wouldn’t this technically be a Trojan, after the groups of asteroids that follow Jupiter and a few other planets around?
    Or do Trojans just hang around a particular point in a planet’s orbit?

    Trojans occupy the L4 and L5 Lagrangian points. So Cruithne is not a Trojan.

  38. Nigel Depledge

    D’oh! Ivan3man beat me to it.

  39. Nigel Depledge

    BTW, anyone who wishes to watch more QI but has the misfortune to live outside the UK…

    The first three series (A, B and C) are available from on Region 2 DVD.

    I think QI is the best BBC programme since they started dumbing down Horizon. Not only is it hilarious, not only does it contain many facts and titbits of obscure science, it is the only programme on the BBC that celebrates scepticism (and, yes, because it is the BBC, you have to spell “scepticism” with a “c”, not a “k”). And this is largely due to Stephen Fry.

  40. @ SLC

    Are you out there SLC? I’ve answered a question you asked ages ago on thediffrence between giant and supergaint stars back on the “Wonder twins Telescope sees star’s dying gasps” )(T leporis)thread.

    Have you seen it yet?

    Please let me know. Click on my name to visit the old thread mentioned.

    PS. Hope this doens’t violate netiquette too badly but I just want to know if SLC has seen my reply for him, that’s all.

  41. EdZ

    Another vote for it being a Trojan, in the tradition started around Jupiter’s L5 point, and expanded to L4 (often overriding their ‘Greek’ designation), Saturn’s L4&5 points, Neptune’s, and Mar’s. To me at least, Cruithne’s orbit looks suspiciously like a Tadpole orbit around Earth’s L4 point.

  42. AJ

    Well, I knew about Cruithne quite some time ago… though I was reminded of it by QI, this is true.

    First time I saw it referred to was in a Stephen Baxter sci-fi novel, “Time”

    That was written/printed in 1999.

  43. Gary Ansorge

    The Space Studies Institute is quite interested in Trojan objects, since some at least should be carbanaceous, which have significant quantities of volatiles, probably including Hydrogen/oxygen compunds. The main advantage to such “Trojans” is that the delta V required to reach them from earth and return is much more energy effective than retrieving raw materials from the moon. Great for space construction/life maintenance. I belive the Solar observation sats are nearly in position to travel thru the L4/L5 points. There is a plan to observe the local area and see if any Trojans are detectable.

    Gary 7

  44. Winter Solstice Man

    Steven Fry was also an actor in the films I.Q. (with Albert Einstein played by Walter Matthau) and V for Vendetta by some guy who also wrote some obscure comic book about some Watchmen.

  45. Torbjörn Larsson, OM

    IVAN3MAN, thanks! Also, I should have realized it is best described as the resonance it is.

    @ Winter Solstice Man:

    Which obscure comic book will be a movie, yeah – but – Quis custodiet ipsos custodes? (“Who will watch “The Watchmen”?) ūüėČ

  46. CR

    @ Matt A
    LOL over your apologies to me!
    Also, thanks for the new link.

  47. Hoyvin-Mayven

    Wooster: “Do you know everything, Jeeves?”
    Jeeves: “I really don’t know, Sir.”


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