August 30

August 30

The Fish's Mouth Opens

Sun Position

The Sun is in Virgo at approximately +6° declination. The Northern Hemisphere is unmistakably in the last weeks of summer; the Southern Hemisphere is closing in on the spring equinox.

Sky Highlight

In the final days of August, the autumn constellations (Pegasus, Andromeda, Aries, Perseus) are fully risen by midnight from northern mid-latitudes, and southern observers are gaining the rich spring sky of Centaurus and the Large and Small Magellanic Clouds in the southeast. This is one of the few weeks when both the Milky Way and the andromeda-group galaxies are simultaneously well-placed.

Deep Sky Object

NGC 7009, the Saturn Nebula in Aquarius, is a compact but vivid planetary nebula roughly 2,400 light-years away, named for the extended 'ansae' or handle-like projections on its disk that faintly resemble Saturn's rings in a small telescope. It is well placed in late August evenings for observers at most latitudes and brightens considerably with higher magnification.

Featured Star

Fomalhaut, the A3Va main-sequence star 25.1 light-years away in Piscis Austrinus, rises in the southeast in late August evenings and is the southern sky's brightest isolated star, 'the loneliest bright star' in some traditions, sitting in an otherwise faint region of sky. The debris disk surrounding it, roughly analogous to our Kuiper Belt, was the first circumstellar disk directly imaged in optical light.

Around This Date

  • August 25, 2012Voyager 1 crossed the heliopause, entering the interstellar medium at a distance of about 121 AU; the crossing was dated retroactively from plasma oscillation measurements made in 2013.
  • August 28, 1993The Galileo spacecraft discovered Dactyl during its flyby of asteroid 243 Ida, photographing it at distances as close as 9 kilometers, small enough that Dactyl's surface features were just barely visible.

Fomalhaut is rising with a ring around it that we can photograph from here, 25 light-years is nothing in galactic terms, but it is close enough to see the architecture.