October 19

October 19

The Still Point

Sun Position

The Sun is in Libra near -12.5° declination. In the Northern Hemisphere, evenings are growing noticeably cool and dark earlier; the Southern Hemisphere is entering the warm expansiveness of late spring.

Sky Highlight

Polaris (the North Star) is a useful reference on any October night, and mid-autumn is a good time to verify its true position: not exactly at the celestial pole, but currently within about 0.7° of it, slowly spiraling toward closest approach around 2100. Circumpolar constellations Cassiopeia and Ursa Major are on opposite sides of Polaris on October evenings.

Deep Sky Object

NGC 7789 (Caroline's Rose), an open cluster about 7,600 light-years away. NGC 7789 in Cassiopeia, discovered by Caroline Herschel in 1783, is one of the richest open clusters in the northern sky, about 1,000 stars packed into a circular area, whose interlocking chains of stars give the cluster a rose-like pattern under telescopic magnification. Best for Northern Hemisphere observers; low or inaccessible from far southern latitudes.

Featured Star

Polaris (α UMi) is a yellow-white supergiant (F7Ib) about 433 light-years away and, like Almach, a multiple system. It has two known companions. Its position near the north celestial pole is a coincidence of the current era: precession will carry it away from the pole over the next several thousand years, handing the north-star role eventually to Vega and then others. Polaris, the still point, while all other stars wheel around it.

Around This Date

  • October 19, 1910The International Astronomical Union's predecessor body formally adopted the standard 88 constellation boundaries in a process that would culminate in Eugène Delporte's official delimitation in 1930.
  • October 20, 1968Apollo 7 returned to Earth after the first crewed Apollo mission, splashing down successfully and confirming that the redesigned spacecraft was ready for lunar-trajectory missions.

Polaris earns its reputation not by any special brilliance but by holding still while everything else moves.