October 23

October 23

Autumn's Best Double

Sun Position

The Sun enters Scorpius near -14.5° declination. In much of the Northern Hemisphere, October 23 marks a threshold: evenings feel genuinely dark rather than merely dim by 7 PM.

Sky Highlight

Late October is an excellent period for deep-sky observing in the Northern Hemisphere: the Milky Way runs from Cassiopeia through Perseus and Auriga, Perseus and Andromeda host multiple galaxy targets, and seeing typically stabilizes after the summer heat haze. Southern Hemisphere observers enjoy spring transparency and the Large and Small Magellanic Clouds at good elevation.

Deep Sky Object

SMC (Small Magellanic Cloud), an irregular dwarf galaxy about 200,000 light-years away. The Small Magellanic Cloud is a satellite galaxy of the Milky Way and a naked-eye object from southern latitudes, a detached fragment of the Milky Way visible to the naked eye, containing billions of stars and serving as a key laboratory for studying stellar populations at a known distance. Visible only from Southern Hemisphere and low southern latitudes of the Northern Hemisphere; circumpolar from most of the Southern Hemisphere.

Featured Star

Almach (γ And) is an orange giant and blue main-sequence pair (K3IIb + B9.5V) about 355 light-years away, and it is at its best October elevation for Northern Hemisphere observers this week. The color contrast between the two primary visible components (gold-orange and steel-blue) makes it one of the most satisfying eyepiece sights of the autumn season. Almach, orange and blue at Andromeda's foot, a quadruple star disguised.

Around This Date

  • October 24, 1946A V-2 rocket launched from White Sands, New Mexico returned photographs taken at an altitude of 105 km, the first photographs of Earth taken from space, showing the curvature of the horizon.
  • October 23, 2003The Sun produced one of the strongest solar flare events on record (the Halloween solar storms) which disrupted satellite communications and produced aurorae visible at unusually low latitudes.

Almach is the kind of object that converts people who thought double stars were a lesser category of astronomy.