Iapetus, outermost of Saturn's major regular moons, extraordinary because of its great contrast in surface brightness.
Planetary nebulae typically appear as rather round objects of relatively high surface brightness.
"The cheap, childish chirp of surface brightness is set against the ominous, subterranean rumblings of tectonic plates grinding together".
Often, a deep, or primary, minimum is produced when the component having the higher surface brightness is eclipsed.
So the surface brightness tells us about the ferocity of the nuclear reactions that were taking place hundreds of thousands of years ago.
Rhea resembles Saturn's moon Iapetus in size and density, but the distribution of its surface brightness is opposite to that of Iapetus and less extreme.
Perhaps she is, but highlighting Hedda's surface brightness and 'tude, as Burton does, makes the play feel dated and her fate inexplicable — it seems self-determined and unconnected to social forces.
They differ little in total surface brightness; near the limb the moon is somewhat brighter than the planet's surface on which it appears projected, but near the middle of the disk it is hardly distinguishable.
Planetary nebulae are considerably denser than most H II regions, typically containing 1,000 10,000 atoms per cubic cm within their dense regions, and have a surface brightness 1,000 times larger.
If a small, high-temperature star is paired with a larger object of low surface brightness and if the distance between the stars is small, the part of the cool star facing the hotter one is substantially brightened by it.
Planetary scientists suspect that this distribution of surface brightness is affected by the deposition of micrometre-sized ice particles from Saturn's E ring, in which Tethys is well-embedded.
