back to article Boffin says Astronomical Unit should be binned

An astronomer based in Canada has published a paper arguing that distances within the solar system should no longer be measured using Astronomical Units (AU), which is currently standard practice. An AU is approximately equal to the distance between Earth and Sun, but the International Astronomical Union actually defines it …


This topic is closed for new posts.


  1. Robert Long


    I was with him until that last part. What the hell's wrong with furlongs?

    Original scientific definition of the metre as dictated by Napoleon to his Minister for Science:

    "Give me a rationale for a measurement close enough to the yard as to make no real inconvenience for people but slightly bigger than the English one."

  2. Keith Martin

    Reg Units?

    Where are the Reg Standard Units? How many Bulgarian Funbags are being lost by the sun every minute?

  3. Anonymous Coward

    Surely they should use...

    the linguini, double-decker bus, or brontosaurus....

  4. Anonymous Coward
    Anonymous Coward

    Wikipedia explains why astronomical units are still used

    According to "While the value of the astronomical unit is now known to great precision, the value of the mass of the Sun is not, because of uncertainty in the value of the gravitational constant. Because the gravitational constant is known to only five or six significant digits while the positions of the planets are known to 11 or 12 digits, calculations in celestial mechanics are typically performed in solar masses and astronomical units rather than in kilograms and kilometres."

  5. Richard Pennington

    Solar mass loss

    Well, actually the Sun is losing mass ... but far more is lost via the solar wind than by the conversion of mass into energy. Still not very much in comparison with the total mass of the Sun, though.

  6. xyz
    Paris Hilton

    The inaccuracy of decimal places

    I'm with the "testy boffin" on this one.

    A conversion of "Testy boffin" from AUs to clicks, would come out something like "Testis boffer". Close but no Clinton.

    ...and should be known as "The Paris probability"

  7. Anonymous Coward

    149,597,870,691 metres it is then

    Then again, perhaps the AU is easier to remember.

  8. Steve Mason


    just redefine AU's in terms of the speed of light through a vacuum and be done with it.

    Something around 1AU = 8 lightminutes or similar.

  9. Anonymous Coward
    Thumb Up

    Ultra efficient

    Only 60 aircraft carriers mass equivalent consumed per second?

    That's an unbelievably small loss compared to the thermal output we feel 1AU away (gotta use AU before it's banned).

    Hurry up someone and get some fusion power plants working!

  10. Ross


    I've never been a fan of the AU just because it's a stupid unit*, but all real units (as in those based on the distance between two actual points in space) change. I seem to recall a story a little while ago about the length of the metre changing (well, the piece of metal that determines its length anyway)

    By my very poor maths the Sun will lose half of its mass in the next 95 billion millenia at that rate, although as it only has another few million years of fuel left I think that theory has its limitations :)

    Whilst the AU may change by a tiny, possibly immeasurable distance I don't see that as the reason it should be binned. It sucks - isn't that reason enough?...

    *totally personal opinion - not scientific fact :)

  11. Ben Parr-Ferris

    The question has already been resolved

    in favour of the brontosaurus.

  12. John Hawkins

    No more global warming. Eventually.

    Burn that coal chaps - we're going to need the extra CO2.

  13. Ginger

    Future problems

    And just think of the chaos that'll be caused when the sun becomes a red giant and engulfs the earth and 1AU is -238547km

  14. Anonymous Coward
    Anonymous Coward


    Is that preggers or not?

  15. Nick Rutland


    "He proposes using metres instead."

    Even allowing for our US friends who can't spell properly...

    That's presumably quite a lot of metres, then.

  16. Anonymous Coward


    "...or 80-million-odd international adjusted Sarah Beenys completely annihilated."

    Of course, even the international adjusted Satah Beeny mass is not a constant...

  17. This post has been deleted by a moderator

  18. Anonymous Coward

    standard unit for the masses.

    surely they should use the "football field" so "science" magazines and blogs can save time converting the units.

  19. regadpellagru

    Meters and not yards ?

    "The testy boffin reckons variance in the AU could account for the so-called "Pioneer anomaly", in which NASA's Pioneer space probes have wandered off their calculated courses since heading out into interstellar space."

    Interesting. Would have been good to elaborate on this one, though, even if it could become a bit technical. Never could get used to AU, myself, as an astronomy student, too odd to be trusted. Same goes for the parsec which derives from AU. Ligh-year is better since defined by physics.

    "He proposes using metres instead. ®"

    Really ? Not yards, inches and miles ?

    </sarcasm aimed at imperial units (all of them)>

  20. Stuart

    What a load of tosh

    Complete garbage.

    AU are never used for serious scientific measurement, and anybody who does should be sacked.

    They exist for illustrative/comparitive purposes, i.e. Mars is aprox 1.5 AU means it orbits 50% further form the sun than the Earth. Mars orbitting at 220 billion meters from the Sun doesn't mean anything to anybody.

  21. Paul Williams

    The AU is merely a handy comparison unit...

    ....used only for estimation.

    No-one would ever use it "for scientific and engineering usage".....

    Surely he's not suggesting that scientists and engineers would use such strange units as AUs per millenium, rather than m/s?

  22. Ken Hagan Gold badge

    Re: Wikipedia explains why astronomical units are still used

    Wikipedia's argument is weak. Our uncertainty of big G hasn't stopped us measuring the distance to the moon to the nearest centimetre. Now that satellites have orbited most of the major bodies in the solar system, we probably know just about every distance to surprisingly high precision.

    It seems to me that the AU remains in use because distances quoted in AU are less of a mouthful than those quoted in metres or km and because Gm and Tm just haven't found their way into common usage. The idea that anyone might use it for precise calculations in celestial navigation is, er, surprising since the velocity of spacecraft probably aren't measured in AU/century so you'd have to include a AU-to-metres conversion somewhere in your program anyway. Still, if you are still using body parts to measure size (fnarr fnarr), anything's possible.

  23. Luther Blissett

    Pioneer anomaly

    No it's not. The Pioneers know better than the Luciferians that the Creator does not live in the Sun and are accelerating onwards and outwards to meet Him all the sooner like the pure and noble (aka innocent and naive) creations that they are.

    Or to meet Her. (That would be cool - after all, the Creator is the max. So he/she/it has got to be Max cool. Not excepting that the singular could be a plural masquerading under a collective noun - like a Hive Mind. That would be even cooler). So, Hers even.

    The idea that the Sun's miniscule loss of mass is causing the Pioneers not to be where boffins thought they should be is outlandish and preposterous but par for the course. So what else could make the solar wind defy gravity apart from disgust with Luciferianism?

  24. Anonymous Coward

    @ Ross

    The length of a metre is no longer defined by a piece of French metal. Instead, it is taken to be the distanced travelled by light in a vacumm in 1/299,792,458 s.

    You're thinking of the international standard kilogram, which IS still a piece of French metal whose mass appears to be diverging from its official copies stored elsewhere around the world.

  25. Claus P. Nielsen

    AU may be flawed, but Mach numbers are even more ridiculous

    Especially when (as recently seen in the press) they are used to describe the speed of a (paper) space shuttle reentering the earths atmosphere.

    So what exactly is the speed of sound in vacuum?

  26. Rich

    Re: "I've never been a fan of the AU just because it's a stupid unit"

    I think Fahrenheit must be the king of stupid units. I can't remember the exact details, but this is really a "made up on the back on an envelope" job. It has no relation to any physical constant (Celsius is (or was until a more precise definition was invented), of course, linked to freezing/boiling point of water). I do know that Fahrenheit was based on some previous scale though and Mr. Fahrenheit added 2 to that old scale just to make it different. Yes, really - it's THAT random!

    Goodness knows why the Americans still use the damned scale - it's rubbish!

  27. Lloyd Kinsella
    Dead Vulture

    The Reg's own measurement flaw

    You say 60 US Navy Aircraft carriers, however which class of carrier there are several with different displacements?

  28. Paul F

    Does he want to redefine years?

    Since the orbital period of the Earth is changing, why not change that too? How about Days? Those are slowing as well!

  29. adnim Silver badge

    It is..

    all guess work, theory and speculation.

    Gravity does not exist. Space is bent and bent space causes deviation from a straight path not gravity. Wind would not exist without air. Gravity would not exist without bendy space. Gravity is like the wind or a Sarah Beeny fart.

    Dark matter and dark energy do not exist, all the virtual particles popping in and out of existence are causing the accelerating expansion of the Universe, a kind of reverse Casimir effect. The Universe expands into nothing, and that nothing cannot fight the pressure caused by the elusive virtual particles that survive the sucking into black holes that their partners that they would normally mutually self destruct with undergo. Because of the accelerating expansive nature of the Universe the metre is also meaningless and is varying over time.

    Our brains work on a quantum level so not only is the Universe out there, it is part of our minds' inner function, this explains why logic is beyond the understanding of many individuals. Especially Tom Cruise and the superficially gorgeous Paris.

    The best measure of spacial distances is the Dirac constant which is the length of a plank divided by 2 pies. As most of us, myself included are as thick as a plank when it comes to such things, this seems highly appropriate.

  30. simon
    Black Helicopters

    Re: wikipedia

    well anyone not using SI units for everything, is probably being payed by the hour, and thinks they will be employed again when it all goes tit's up.

    and, there really are a lot of problems in the basic physics stuff on wikipedia, what i'm guessing is happening is that since the factual stuff and current events seem very good, is that the consensus mechanism used there, is self-reinforcing common misconceptions, and as a wild guess, this is concentrated in the physics sections because there are a lot of chemists in the US with time on their hands and who have developed the same high level of, unchecked, confidence in their physics understanding.

  31. William Towle

    "Not supposed to change"

    "Units are not supposed to change," [Noerdlinger] told New Scientist, describing the situation as "quite a nuisance".

    ...reported the author of the line "three millionths of a quadrillionth goes every second if we've got our sums right; or three billionths of a trillionth if you prefer"!!!

    Well, it amused me.

    (In deference to my appreciation that Lewis /is/ writing for an international audience, here a reference [for everyone else] to what he means by "prefer":

  32. Jon


    was based on freezing point of salt water (assumed to be the coldest you could go), 0, with body temp at 100 but for some reason was out.

  33. GrahamT

    Taking this to its (il)logical conclusion

    The yard should be scrapped as it is based on the length of Henry VIII's arm, and that arm has now withered away;

    the mile because it is 1000 double paces of a Roman Legionnaire, and there aren't too many of those marching around;

    and the metre was originally based on 1/10,000,000th the distance from the pole to equator, and we all know the Earth is not a sphere so that is not a standard distance.

    The point is, many units are (or were) based on things that are no longer available/accurate/realistic, so a new basis of measurement is agreed, e.g. the wavelength of light at a particular frequency, or a bar of Invar in a laboratory, and we carry on as usual - this "issue" is much ado about nothing.

    (Of course frequency is based on time being constant, whereas time can be bent, so nothing is 100% accurate.)

    btw, good to see MfM firing on all cylinders - straight to the point as usual.

  34. Gerhard den Hollander


    I seem to remember Mr Fahrenheit used the coldest temperature he had encounterd as 0, and used the highest temperature of a feverish body as 100, and then scaled between them.

    Fahrenheits thermometers were more accurate then the ones made by Mr Celcius though

  35. simon
    Black Helicopters

    Re: Re: "I've never been a fan of the AU just because it's a stupid unit"

    i think all the old 'units' are now referenced to SI ones anyway, or have been forgotten, so Fahrenheit is 'measured' in Kelvin, Fahrenheit isn't a 'real' unit anymore, its just a different way to read the SI units.

    BTW i heard that, zero Fahrenheit has something to do with all life stopping, and one hundred Fahrenheit was people/blood/core/life temperature, guess the guy might of been a biologist.

    but does it really matter whats on your thermostat, i think hot and cold would probably do it for people still using that scale.

  36. Anonymous Coward
    Anonymous Coward


    How many people that _really_ care about this don't have beards? I bet it's a very low number...

  37. GrahamT

    Mr Fahrenheit @Rich

    Hear, Hear,

    I was bought up with Fahrenheit and have now managed to almost forget it.

    Apparently Fahrenheit based zero degrees on the lowest temperature he could get - his equivalent of absolute zero - a salt and ice mixture, and 100 (Wikipedia says 96) was that universal constant, the temperature of the human body - he must have had a fever (or a chill). The freezing and boiling points of water were just extrapolated from there. (I was taught this at school, so it must be right!)

    Anyway, 0 for freezing, 20 for a nice spring day and room temperature, 30 for a hot summer's day, 40 for a heat wave or a hot bath, and 100 for boiling water. What could be simpler?

  38. simon

    Re: Taking this to its (il)logical conclusion

    things have to be in relative motion for time to run at different speeds, so unless your MI5 eavesdropper is in a van, he should be able to gauge the level of stress in your voice accurately.

  39. Anonymous Coward
    Anonymous Coward

    @Robert Long

    Actually, a meter isn't that arbitrary, it is 10 times longer than the size of a cube that holds a liter of water which weighs a kilogram.

    Besides, what is so silly about using meters to measure things in space? You just need to measure in Megameters, Gigameters, etc. I mean my hard disk contains 320,062,062,592 bytes, but that doesn't stop me from measuring it as 300GB, forget the unnecessary precision.

  40. Tim


    The tool of the devil! My car gets 40 rods to the hogshead and that's the way I likes it.

  41. Anonymous Coward


    "The length of a metre is no longer defined by a piece of French metal. Instead, it is taken to be the distanced travelled by light in a vacumm in 1/299,792,458 s."

    1/299,792,458?? Fahrenheit doesn't seem so odd after that!

    My coat's the North American 'large' not the Made in China 'large'.

  42. JeffyPooh Silver badge

    Google Calculator sez:

    1.0 Astronomical Unit = 8.79057469 × 10^10 Smoots

  43. Anonymous Coward


    Sorry, of course I meant fahrenheit and the rest of the IMPERIAL lot. I was distracted trying to use my 3.4 sided ElReg ruler.

  44. Bounty

    @ Brent Gardner

    Is your hard drive measured in binary or decimal bytes?

    Also I'm cool with Mars at 227 Gm's from the sun and the Moon at 348 Mm's from Earth etc.

    Also... try to remember... from wikipedia (stop laughing!)

    "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom." and "at rest at a temperature of 0 K"

    to calculate your seconds, which define the speed of light, which defines the meter. Try not to sneeze on your caesium, as the change in pressure might alter the speed of light, and the distance to to Mars... or anyone on it.

  45. Anonymous Coward
    Anonymous Coward

    @Brent Gardner

    "...forget the unnecessary precision"

    If precision isn't necessary can we just carry on using AUs please.

  46. Red Bren
    Paris Hilton

    @Claus P. Nielson

    The speed of sound in a vacuum is slightly slower than the speed of the valuable object you think you've just accidently hoovered and slightly faster than that sinking feeling when you search through the dust bag and find it was just a penny. It's certainly a lot slower than the speed of a mobile phone thrown by a super-model at a domestic servant after hoovering said valuable object.

    Paris, coz there's no Naomi icon

  47. Justin

    AUs cancelled - world about to end

    Without the AU, I am never going to be able to play "Frontier Elite" ! This is a complete disaster. I often wondered if the AU was different in each solar system... and by the way I don't have a beard!

  48. Graham Dawson


    Farenheit is not an imperial measurement. Never was. The whole farenheit vs celcius thing is completely independent to metric vs imperial. I mean, at least imperial measures are based on things that matter (Elizabeth the first and her new miles notwithstanding) and have a logical progression of sorts. Farenheit is just *weird*.

  49. Mark

    re: 149,597,870,691 metres it is then

    CURRENTLY, yes. But with the expansion of the universe this isn't actually all that accurate either.

  50. Skullfoot
    Paris Hilton

    No.. not meters!

    No we should measure the whole chummin bit in lengths of a Paris Hiltion Jail sentnece! Damn folks its called TIME SPACE for a reason!


This topic is closed for new posts.

Biting the hand that feeds IT © 1998–2019