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metricadvocate

I nominate this sentence for the most absurd mix of units ever, and further deny the asteroid fits easily in two football pitches (Soccer fields in American): The asteroid is about 490m wide and roughly about 0.219km to 0.490km in diameter, meaning it can easily fit in two football pitches. Also, author, please remember the mandatory space between number and unit is, well, **mandatory**. Finally, this object was removed from JPL's Neo threat board in 2008 (same year as discovered). The 0.05 AU criteria seems rather large, but they forecast orbits at least 100 years in the future and when the orbital data is still "rough" that is a reasonable criteria. The probability of impact assumes a normal distribution and Z score based on calculated closest approach and standard deviation. So NASA is more informing than warning.


flatline000

>Also, author, please remember the mandatory space between number and unit is, well, mandatory. Ever since you corrected me in a previous thread, I've been paying attention to online product descriptions and to stories in the media and I don't see anyone putting spaces between the numeral and the unit abbreviation. I do, however, see a space used when they use the unabbreviated unit name. For example, "18 meters" vs "18m".


metricadvocate

Rule is nearly always violated in the UK. I can only quote for the SI Brochure (9th ed): >5.4.3 Formatting the value of a quantity > >The numerical value always precedes the unit and a space is always used to separate the unit from the number. Thus the value of the quantity is the product of the number and the unit. The space between the number and the unit is regarded as a multiplication sign (just as a space between units implies multiplication). The only exceptions to this rule are for the unit symbols for degree, minute and second for plane angle, °, ′ and ″, respectively, for which no space is left between the numerical value and the unit symbol. > >This rule means that the symbol °C for the degree Celsius is preceded by a space when one expresses values of Celsius temperature t. Even when the value of a quantity is used as an adjective, a space is left between the numerical value and the unit symbol. Only when the name of the unit is spelled out would the ordinary rules of grammar apply, so that in English a hyphen would be used to separate the number from the unit. A margin note makes clear that the space is required with symbols for the unit name: >*m* = 12.3 g where *m* is used as a symbol for the quantity mass, but φ = 30° 22′ 8″, where φ is used as a symbol for the quantity plane angle.


flatline000

I'm convinced that your interpretation the the SI Brochure is correct, but I think this is a case where the rest of the world has accepted a typewritten convention that more closely mimics how we write numbers and units by hand rather than what is prescribed. I did manage to find some examples of units separated by a space from the scaler in some old academic papers that I found online (and it looked really strange), but newer papers don't seem to honor the space at all. It would be interesting to see what the style guides for different scientific journals have to say if they mention it at all. Elsevier's style guide doesn't, but it's so short that I expect that they must have style guides for their individual publications that didn't come back when I googled for it. Communicating clearly is more important than strict formatting, so as long as it doesn't hurt readability or insert ambiguity somehow, I wouldn't fight it.


metricadvocate

USMA style guide as an example: [https://usma.org/correct-si-metric-usage](https://usma.org/correct-si-metric-usage) Most of Chicage Manual of Style is paywalled, but this FAQ is relevant: https://www.chicagomanualofstyle.org/qanda/data/faq/topics/Abbreviations/faq0028.html


gobblox38

wtf is a football pitch?


Liggliluff

An undefined area


oscarboom

> wtf is a football pitch? I was wondering the same thing. If they would have said "hectometer" instead of "football pitch" I would have understood immediately though.


klystron

The British name for a football field.


gobblox38

Which is a soccer field, right? So that's like, 7 stones long or something? I don't know British measurements.


klystron

Unlike a gridiron football field, which is a fixed size, [an Association Football field is variable:](https://yoursoccerhome.com/a-complete-guide-to-a-soccer-field-size-and-dimensions/) >A soccer field is between 100-130 yards (90-120 meters) long and 50-100 yards (40-90 meters) wide. However, these dimensions change for an international game. An international soccer field must be between 110-120 yards (100-110 meters) long and 70-80 yards (64-75 meters) wide. > >Measured in feet, the dimensions of a soccer field are a minimum of 210 feet and a maximum of 240 feet long, and a minimum of 135 feet and a maximum of 165 feet wide. A football pitch can be any size within those limits, but it is not allowed to be a square.


j1ggy

>The closest the asteroid is expected to get with Earth is 5,740,000km. So uh, nowhere near Earth. In the galactic scale, sure, but this thing will be passing by at 15x the distance of the Moon. Or 5.7x the distance of James Webb, which is too far away for manned repair missions. Yawn.


Historical-Ad1170

I can't visualise 5 740 000 km. I'm sure no one else can either. However, I can visualise a distance about 5.74 Gm. The sun is 150 Gm from the earth and the moon is 384 Mm. With these small numbers to work with, the visualisation of the distances is much easier to discern. Using these big 8 digit numbers confuses the scale for everyone, even if they don't care to know.


oscarboom

>I can't visualise 5 740 000 km. I'm sure no one else can either. However, I can visualise a distance about 5.74 Gm. The sun is 150 Gm from the earth and the moon is 384 Mm. Exactly! 5.74 gigameters is about 10% of the distance from Mercury to the sun (58 Gm). Everything is so much easier to comprehend when you ditch kilometers and use metric units appropriate to the scale.


j1ggy

I just have it memorized that the Moon is 384,000 km away on average. You can use that as a quick reference to know whether these articles are BS or not.


Historical-Ad1170

I have the distance to the moon memorised as 384 Mm. I try to keep it simple by using SI, choosing prefixes so the values fall between 1 and 1000. All of the planets from the sun to Jupiter can be expressed in gigametres and all of the planets past Jupiter in terametres. all of the distances to the planetary moons are in megametres. The diameter of the milky way is 1 Zm. Try expressing that in kilometres. The observable universe is 880 Ym in diameter.


oscarboom

> I have the distance to the moon memorised as 384 Mm. I try to keep it simple by using SI, choosing prefixes so the values fall between 1 and 1000 Me too. I have so many astronomy distances memorized as SI meter units that whenever I see a distance given in km or au or ly from a scientific article or science fiction story I convert it in my head to metric si units to do a sanity check and understand it relative to everything else.


Historical-Ad1170

Astronomy is one of the most backwards of the natural sciences. Their refusal to fully adopt SI units is the primary reason in my opinion.


klystron

I found this article on [Fark.com](https://Fark.com), and one person there commented that the asteroid was deemed to be close if it came to within 5% of an Astronomical Unit at its closest approach. 1 AU is 150 000 000 kilometres so a close approach is 7 500 000 km, or more than 18 times the distance from the Earth to the Moon. I would suggest that a close approach is one that approaches to within one lunar orbit (\~400 000 km) or less.


Historical-Ad1170

The AU in 2012 had to be defined to an exact number of metres, that being 149 597 870 700 m. The need for this exact definition must have meant there was a problem with measurements of spacial objects due to the constant changing of the distance from the earth to the sun. So, why is this so-called feral unit still in use? It's no wonder that astronomy is one of the most backwards of the sciences. It's almost like astronomy is just an offshoot of astrology.


redcookiestar

Disappointed it’s not closer. These articles are teases. After everything else the world has been through in recent days, doomsday by meteor is well overdue.


BubbaClegane

Ok, but how smoots away is it? And how many GBTs (Grits-Boiling-Time) do we have?


metricadvocate

Approx 3.37 gigasmoots.


gobblox38

I learned about smoots when showing a coworker hire to use the line tool on goggle earth.


creeper321448

I love these article titles they're hilarious. Yes, I am 8.85 maple syrup jugs tall. For those who aren't Canadian, that is approximately 7.5 Soccer balls tall or 0.018 American Football fields.


klystron

The good news is that the article used metric measurements only, apart from comparisons with office buildings and football pitches. On the other hand, they need to be consistent about their choice of measurements. From the article: >The asteroid is about 490m wide and roughly about 0.219km to 0.490km in diameter, meaning it can easily fit in two football pitches. Isn't 490 metres equal to 0.49 km? Why not write "The asteroid measures approximately 220 metres by 490 metres."? Also, can astronomers measure an asteroid with a precision of 1 metre (ie, why 219 metres and not 220?) when it's nearly 6 million kilometres away? The article seems to have been reproduced from the British paper, *The Metro*, and mentions another asteroid that passed close to Earth in February, saying it was as big as The Shard, a landmark London office building.


Historical-Ad1170

You should complain about this as well: >The closest the asteroid is expected to get with Earth is 5,740,000km. >That’s more that the distance between the Earth and the moon which is around 385,000km – so we’ll probably be alright. What's so wrong with saying the closest it will come to earth is 5.74 Gm? Why this idiotic need to mix prefixes with counting words instead of just using the correct prefix? The moon is 384 Mm from the earth.