July 12
The Divided Serpent
Sun Position
The Sun is in Cancer at about +20.8° declination, moving toward Leo. Northern Hemisphere days are still long but very slightly shortening; Southern Hemisphere winter holds steady.
Sky Highlight
No major annual event peaks on July 12. Serpens is the only constellation split into two non-contiguous parts, Serpens Caput (the head, in the west) and Serpens Cauda (the tail, in the east), divided by Ophiuchus. Both sections are reasonably well-placed in July evenings from northern and equatorial latitudes.
Deep Sky Object
M5 (NGC 5904), a globular cluster in Serpens Caput roughly 24,500 light-years away. It is one of the oldest globular clusters known, estimated at over 13 billion years, and one of the largest and brightest. On a dark night, binoculars show a fuzzy star; a small telescope reveals a bright nucleus with granular edges. Visible from both hemispheres.
Featured Star
Unukalhai (α Ser) is an orange giant about 73 light-years away in Serpens, classified K2IIIb. It marks the neck of the serpent and is the brightest star in the only IAU constellation split into two disconnected pieces, a peculiarity of constellation boundary drawing rather than any physical property of the star itself.
Around This Date
- July 12, 1966NASA's Gemini 10 mission launched, completing a dual rendezvous with two different Agena target vehicles, the first time a spacecraft had maneuvered to meet two separate orbital targets on a single mission.
- July 14, 1965Mariner 4 made the first successful flyby of Mars, returning 21 close-up photographs that showed a heavily cratered, Moon-like surface and deflated early hopes of finding a habitable planet.
Unukalhai holds the neck of a constellation that no other constellation dares to imitate, split in two, and still coherent.