> http://www.nasa.gov/mission_pages/sdo/news/first-light.html


Here (above) is the link to NASA's page on which this photo and caption were 
found, in case you want to see it yourself.

Below is a copy of my original message in case you need to refer to it again.

Regards,
Bill Hooper


==============================
Amazing! (Amazingly stupid!)

This below is the caption of a photo of the sun. Thankfully, the temperatures 
are given in kelvins, as the primary data, but then someone who has no concept 
of the idea of precision (or the meaning of the word "about") made ridiculously 
"precise" (and unnecessary) conversions to Fahrenheit.

> A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO 
> on March 30, 2010. False colors trace different gas temperatures. Reds are 
> relatively cool (about 60,000 Kelvin, or 107,540 F); blues and greens are 
> hotter (greater than 1 million Kelvin, or 1,799,540 F). Credit: 
> NASA/Goddard/SDO AIA Team

I checked their arithmetic (in an attempt to find out how they did their 
conversion) and find that they not only accounted for the trivial (in this 
case) 273 kelvin difference between 0 ˚K (absolute zero) and 0 ˚C but they even 
included the ultra trivial 32 ˚F to account for the difference between the 
freezing point in Celsius and the freezing point point in Fahrenheit.

Without those trivial extra terms, one needs only to multiply by 9/5, the ratio 
between a Fahrenheit degree and a kelvin (or a Celsius degree). 
Doing that results in 60 000 K = 108 000 ˚F
This could be further rounded to 100 000 ˚F (or at most 110 000 ˚F) considering 
the rather vague approximation indicated by the 
phrase "ABOUT 60,000 Kelvin". (I would add that I am reasonably well versed in 
astronomy and know that such temperatures cannot be measured much more 
precisely than that in any case.) Certainly 100 000 ˚F is a more reasonable 
result than 
the impossible precision implied by the value of 107 540 ˚F.

Similarly, the one million kelvin figure (1 000 000 K) when converted to 
Fahrenheit should be rounded 
to 1 800 000 ˚F, not the downright silly extreme of 1 799 540 ˚F.

Beside the above travesties of impossible precision, one would want to 
criticize the way the  units of the initial data are shown: The first should be 
written as 60 000 K or as 60 000 kelvins (no capital K here). The second should 
probably 
be 1 000 000 K or "one million kelvins". 

Even better would be to show the temperatures in kilokelvins: 
60 kK and 1000 MK. Also, the second one could be shown as 1 MK.







Reply via email to