Absolute magnitude from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction is applied. For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit. In stellar and galactic astronomy, the standard distance is 10 parsecs (about 32.616 light-years, 308.57 petameters or 308.57 trillion kilometres). A star at 10 parsecs has a parallax of 0.1″ (100 milliarcseconds). Galaxies (and other extended objects) are much larger than 10 parsecs, their light is radiated over an extended patch of sky, and
Only a Trillion only a trillion. Floyd C. Gale stated that Asimov "[a]lmost certainly had enormous fun writing this collection of articles. He staggers, frightens, amazes and, in two, fiendishly misleads his reader". Following the publication of "Only a Trillion", Asimov compiled several more science essays into the manuscript for another, similar book titled "Only a Light-Year", but that book was never published. Only a Trillion Only a Trillion is a collection of ten science essays and three scientific spoof articles by Isaac Asimov. It was the first collection of science essays published by Asimov. It was first published by Abelard-Schuman in 1957.