I’d never really seen the Milky Way until I saw it on a perfectly clear and moonless July night from a spot just below the Arc Dome in central Nevada. It spills a swath of patchy luminosity that seems to split the sky in half; a barred spiral galaxy, seen edge-on, and from within. One hundred billion intensely glowing stars, like sand grain jewels, each separated by miles. The photo above (taken by Steve Jurvetson last weekend from the Black Rock Desert in Nevada) reminded me of that experience.
Under a totally dark sky, you can distinctly see the star clouds in the foreground of the galactic center. It’s eerie to think that the 3-million solar mass black hole lurking in the center of the galaxy is just to the right of the bright luminosity of Baade’s Window near the boundary between Sagittarius and Scorpius.
The photo also shows Jupiter within a few degrees of Antares — a nice illustration of the fact that Jupiter appears slightly brighter than the brightest stars.
Newton used this similarity in apparent brightness to get the first real estimate of the staggering distances to the stars. He assumed that the stars are similar in absolute brightness to the sun, and he assumed that Jupiter (whose distance and angular size were known to him) is a perfect reflector of sunlight. This method underestimates the distance to Sirius by more than a factor of five, but it does a fairly reasonable job for Alpha Centauri.