September 16
The Ringed Debris Field
Sun Position
The Sun is in Virgo at about -2° declination. The autumnal equinox is within one week; nights are growing longer in the Northern Hemisphere and shorter in the Southern Hemisphere.
Sky Highlight
The September equinox (the moment the Sun crosses the celestial equator heading south) falls on approximately September 22–23 each year. At that exact moment, day and night are nearly equal at all latitudes. The intervening days are excellent for comparing twilight duration across latitudes.
Deep Sky Object
NGC 253, Sculptor Galaxy. About 11.4 million light-years away, NGC 253 is one of the closest and brightest starburst galaxies, with vigorous star formation visible in its dusty lanes. It is high and well-placed for Southern Hemisphere observers; requires a very clear southern horizon from northern mid-latitudes.
Featured Star
Fomalhaut (α PsA), spectral class A3Va, is just 25 light-years away and encircled by a sharp, narrow debris ring about 133–158 AU in radius. A candidate planet within the disk, designated Fomalhaut b, was directly imaged by the Hubble Space Telescope in 2008, though its nature remained debated for years afterward.
Around This Date
- September 16, 1961Pakistan established the Space and Upper Atmosphere Research Commission (SUPARCO), with Nobel laureate physicist Abdus Salam as its founding head, making it one of the earliest national space agencies in Asia.
- September 16, 2021Inspiration4, the first all-civilian orbital crewed spaceflight, launched from Kennedy Space Center aboard a SpaceX Crew Dragon, spending three days in orbit before splashing down in the Atlantic.
A debris ring is simply a solar system still sorting itself out. Fomalhaut's disk is our own early history, happening again, 25 light-years away.