November 13
The Former End of the River
Sun Position
The Sun is in Scorpius near -21° declination. Northern Hemisphere days are short; Southern Hemisphere is closing in on its solstice, with long afternoons and short nights.
Sky Highlight
The Leonid meteor shower is approaching its peak, which falls around November 17–18. The Leonids are fast (roughly 71 km/s) and leave persistent trains. Most years produce modest rates, but the shower has a history of extraordinary storms when Earth passes through a dense debris trail from Comet 55P/Tempel-Tuttle. Worth watching from both hemispheres.
Deep Sky Object
M79, globular cluster in Lepus, about 41,000 light-years away. One of the few Messier globulars well-placed in winter evenings (most are summer objects), M79 is thought to be a capture from the Canis Major Dwarf Galaxy rather than a native Milky Way cluster. Accessible from both hemispheres in November and December.
Featured Star
Acamar (θ Eridani) is a matched pair of white stars, a white giant and a white main-sequence star (A4III + A1V), 161 light-years away. It was once the southernmost star in Eridanus visible from the Mediterranean, and ancient star catalogs therefore treated it as the river's mouth; when explorers mapped further south, the endpoint was extended all the way to Achernar. A nice telescopic double.
Around This Date
- November 13, 1971Mariner 9 became the first spacecraft to orbit another planet, entering Mars orbit and eventually mapping 85 percent of the surface.
- November 17, 1970The Soviet Luna 17 deployed Lunokhod 1 on the lunar surface, beginning the first long-duration surface exploration by a remote-controlled rover.
Acamar was the end of the world for observers who couldn't see further south, a boundary set by geography, not the sky.