November 18
The Ram's Belly, Again
Sun Position
The Sun is in Scorpius at about -22° declination. Northern Hemisphere has more dark sky per night than in any other autumn month. Southern Hemisphere summer is progressing.
Sky Highlight
The Leonid meteor shower is at or near its annual peak. Post-midnight watching is most rewarding; the radiant in Leo rises higher as dawn approaches, increasing the rate of visible meteors. Fast meteors with long, glowing trains are Leonid signatures. Visible from both hemispheres before dawn.
Deep Sky Object
NGC 1647, open cluster in Taurus, about 1,800 light-years away. A large, loose cluster of roughly 200 stars spread over a degree of sky, easy in binoculars and beautiful at low magnification in a small telescope. Less celebrated than the Pleiades or Hyades nearby, but worth the visit. Accessible from both hemispheres.
Featured Star
Botein (δ Arietis) is an orange giant 168 light-years away, spectral class K2III. It marks the lower belly of the Ram, and in the ancient lunar mansion systems of Babylonian and Arab astronomers, it served as a calendar star, a fixed reference point for tracking the Moon's position through the month. Nothing about its physical character is exceptional; it is simply old, cool, and reliably there.
Around This Date
- November 18, 1923Edwin Hubble announced his measurement of the distance to the Andromeda Nebula using Cepheid variable stars, demonstrating for the first time that it lies far beyond the Milky Way.
- November 19, 1969Apollo 12 achieved the second crewed lunar landing, with Conrad and Bean landing within walking distance of the Surveyor 3 probe.
Botein has been a calendar marker for three thousand years without doing anything particularly dramatic, some stars earn their place through persistence.