October 9
The Two Signs
Sun Position
The Sun is in Libra near -7.5° declination. The steady tilt of the Northern Hemisphere away from the Sun accelerates the darkening of mornings and evenings; the Southern Hemisphere is pointed progressively toward its summer.
Sky Highlight
The Draconid shower has largely subsided by October 9, and attention shifts toward the Southern Taurid shower, which builds slowly through the month. October 9 is also a good date for observing the Aries region: the three main Aries stars (Hamal, Sheratan, and Mesarthim) are well-placed in the east after dark, a compact group easy to identify.
Deep Sky Object
NGC 772, a spiral galaxy about 130 million light-years away. NGC 772 in Aries is an unbarred spiral galaxy with a notably asymmetric arm structure, most likely the result of tidal interaction with its small companion NGC 770, a good example of how galaxy shapes record their collision histories. Accessible from both hemispheres in autumn, though best from Northern Hemisphere mid-latitudes.
Featured Star
Sheratan (β Ari) is a main-sequence A-type star (A5V) about 59.6 light-years away, a spectroscopic binary whose components orbit each other every 107 days. Its Arabic name comes from the phrase for the two signs, a reference to the old role of Sheratan and neighboring Mesarthim as markers of the vernal equinox in an earlier era. Sheratan, one of 'the two signs,' ancient markers of the start of spring.
Around This Date
- October 9, 1604Kepler's Supernova appeared in the constellation Ophiuchus, visible in daylight for several weeks. It was the last confirmed naked-eye supernova in the Milky Way.
- October 11, 1968NASA launched Apollo 7, the first crewed Apollo mission, which successfully tested the command and service module in Earth orbit for eleven days.
Aries is a small, modest constellation, its historical importance as a zodiacal anchor far exceeds what its stars suggest on a modern chart.