Comet Bigger than the Sun by Miles, Kilometers

The gas cloud around comet Holmes has expanded making it the biggest single object in the solar system, bigger even than the sun. So reports Space.com.

Fascinating stuff. According to measurements by Rachel Stevenson, Jan Kleyna and Pedro Lacerda of the University of Hawaii Institute for Astronomy, on November 9, the coma was 869,900 miles (1.4 million kilometers), which compares with the sun’s diameter rounded to the nearest 100, is about 864,900 miles (1.392 million kilometers).

What’s with those significant figures Space.com? You mention rounding to the nearest hundred by the difference is 5000 miles, so who cares about the four sig figs given in the diameter of the sun? More to the point why give the diameter in miles to four sig figs but the km conversion to just two? Given how these measurements will vary considerably over time, it would be safer just to say “they are the same size, give or take a few km”.

For more on significant figures, the genesis of this blog, check out the original SF post imported from the Blogspot system (other blogging software solutions are available).