General Chat Thread, Am I being pedantic? in General; The BBC are reporting on some planets which have been found;
BBC News - First Earth-sized planets spotted
In it ...
20th December 2011, 11:19 PM #1
Am I being pedantic?
The BBC are reporting on some planets which have been found;
BBC News - First Earth-sized planets spotted
In it they say; "They are both much closer to their star than the Earth is to the Sun and so they complete an orbit much more quickly: 20e circles its star in just six days, 20f completes an orbit in 20 days whereas the Earth takes a year."
Surely a year is defined by how long the planet takes to orbit its sun, so they all take a year, there just may be a different amount of days in the year. And do they mean 6 of its days or the equivalent of 6 earth days?
Or is it late at night and I'm missing something?
20th December 2011, 11:38 PM #2
Measurements like that are defined in earth years.
If we were on that planet, then we would be 28 of that planets years compared to one earth year.
20th December 2011, 11:38 PM #3
They are using established time periods for comparison. Time is measured in the base SI unit of the second and the accepted multiples are in seconds. However, non-SI units accepted in conversion are the minute, the hour and the day (BIPM - Table 6) ... and the missing one is the year. This is partly because the year is regarded as the time taken for the Earth to complete one circuit around the Sun. The Julian Year is an astronomical term defined as 365.25 days, each of 86400 seconds (the SI unit). This is the common frame of reference for comparisons in astronomical descriptions. In some astronomical papers you will see it published as SI seconds (for precision when checking calculations).
A long winded way of saying ... it makes it easy for folk to compare it to what we experience.
Thanks to GrumbleDook from:
Elison (10th January 2012)
20th December 2011, 11:54 PM #4
Taking it further...
Originally Posted by Jawloms
1 day = 1 rotation of the planet.
20e circles its star in just six days, 20f completes an orbit in 20 days
For us it's 24 hours. It may not be the long there.
1 day for them could be 2 days for us. [or more... or less.]
Also, shouldn't "so they complete an orbit much more quickly" be "so they complete an orbit much quicker/faster"?
21st December 2011, 12:01 AM #5
I'm with @Jawloms
The measurements may be understood to be Earth days and years, but this article is about science.
As every science teacher tells their students... unless you give the correct units, what you've written is meaningless.
They should specify which planet's days and years they mean!
21st December 2011, 12:36 AM #6
They are talking astronomy ... there is a correct unit and it is being used ... just not explained very well.
21st December 2011, 07:27 AM #7
And astronomy is a science... The correct units should be clear
Originally Posted by GrumbleDook
21st December 2011, 08:42 AM #8
To answer the original question.
Yes, You're being pedantic.
But hey, it's Christmas.
21st December 2011, 09:18 AM #9
21st December 2011, 10:05 AM #10
It is standard Earth timescales by default. We live on Earth so we use our own times as nobody knows what a 20f, Mars or super-giant-killer-black-hole year is (which would be many millions of years longer then ours if physics and the theory of time dilation is correct, which in turn could affect measurements of these remote planets if you want another spanner!).
21st December 2011, 10:18 AM #11
Ok when you say 'year', what 'year' are we talking about? Calendar or Astronomical?
If Astronomical then what type? Julian, Sidereal, tropical, anomalistic, Draconic, Lunar, Vague, Heliacal, Sothic, Gaussian, Besselian?
C'mon people we need to get accurate here.
21st December 2011, 10:26 AM #12
The article is about detection of earth sized planets. The subject is in the realm of science but the article is not about science.
Originally Posted by elsiegee40
Qui in pedants ostentator - or summat.
21st December 2011, 10:27 AM #13
Comparisons of orbits is usually measured against Julian unless otherwise stated ... and Julian is such a nice person too!
Originally Posted by sparkeh
21st December 2011, 03:15 PM #14
Thanks for clearing it up, I was concerned
Originally Posted by Earthling
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