October 15
Ancient Calendar Markers
Sun Position
The Sun is in Libra near -10.5° declination. Both hemispheres are moving steadily away from equilibrium, autumn deepening in the north, spring accelerating in the south.
Sky Highlight
The Northern Taurid meteor shower, a slower and more diffuse counterpart to the Southern Taurids, begins contributing meteors in mid-October. Both Taurid streams together produce a low but extended background rate of bright, slow meteors through October and November, including occasional fireballs bright enough to cast shadows.
Deep Sky Object
M33 (Triangulum Galaxy), a spiral galaxy about 2.7 million light-years away. M33 is the third-largest member of the Local Group and a legitimate naked-eye object under exceptional dark skies, though its low surface brightness makes it harder to see than its total brightness suggests, a diffuse, fragile smudge that rewards averted vision. Best from Northern Hemisphere mid-latitudes in October; accessible but low from southern latitudes.
Featured Star
Sheratan (β Ari) is a main-sequence A-type star (A5V) about 59.6 light-years away, forming a close spectroscopic binary pair whose orbit has been measured in detail. In Arabic astronomical tradition, Sheratan and Mesarthim together were called al-Sharatain, the two signs, a reference to their former role as equinoctial markers before precession shifted that role westward. Sheratan, one of 'the two signs,' ancient markers of the start of spring.
Around This Date
- October 15, 1997The Cassini-Huygens spacecraft launched from Cape Canaveral, setting off on a six-year journey to Saturn that would yield thirteen years of data from the Saturn system.
- October 18, 1963France launched Félicette, a cat, on a suborbital spaceflight, making her the first feline in space; she was recovered safely after a 15-minute flight.
Stars that once marked the calendar edge have drifted, the sky keeps time differently than civilizations do.