1 The absolute magnitude of a star is a measure of the star's luminosity or its intrinsic brightness. 2  Its the brightness of a star if it were placed at a distance of 10 parsecs.3  The apparent brightness of a star is the star's brightness as it appears in the sky and thus is related to how far away the star is. The absolute magnitude of a star is a measure of the star's luminosity or its intrinsic brightness. 2  Its the brightness of a star if it were placed at a distance of 10 parsecs.
The cores of all four jovian planets are made of some combination of rock, metal and hydrogen compounds. Jupiter and Saturn have similar interiors, with layers extending outward of metallic hydrogen, liquid hydrogen, gaseous hydrogen, and topped with a layer of visible clouds.ll four jovian planets have rings, although only Saturn's rings are easily visible from Earth. Rings are composed of countless small pieces of rock and ice, each orbiting its planet like a tiny moon. The rings look flat because the particles all orbit in essentially the same plane.
While terrestrial planets accreted from planetesimals made of rocks and metals, they ended up too small to capture significant amounts of the abundant hydrogen and helium gas in the solar nebula. The jovian planets, however, formed farther from the Sun where ices and rocks were plentiful.