Light pollution being a topic of particular concern to us, appreciating the fact that we are privileged to be far removed from most of the effects and most holidays too are spend under the stars, we liked learning about the metrics that went into this app—via MetaFilter—that uses the Bortle Scale, which builds and improves upon the way astronomers generally gauge the quality of the observations, naked-eye limiting magnitude (NELM) and judging the apparent brightness of the faintest visible objects, to make a better informed assessment of one’s environs and how far those margins might extend when looking up from a given location. 
The enlightening nine-step classification system with visible phenomena, untethered from a specific constellation or distant galaxy, with the most optimal including the zodiacal band (false dusk), regions of the Milky Way casting shadows on the ground with starshine and the above occurance of counterglow (not pictured—it’s much more subtle than that—see here for an actual attempt to image it), a brighter spot in the night sky centred at the antisolar point caused by the backscatter of sunshine on the opposite side of the Earth by interplanetary dust. Though previously described, the term was coined by Alexander von Humboldt during his South American expeditions, noting that this slightly illuminated spot appeared at midnight.
synchronoptica
one year ago: the asteroid Pallas (with synchropticรฆ) plus Lonesome (1928)
thirteen years ago: more security theatre plus the Vertue of the Coffee Drink
sixteen years ago: hundredth blog post
