August 19
Two White Stars, One Thread
Sun Position
The Sun is in late Leo at around +11° declination. Northern Hemisphere mornings are noticeably dimmer than in June; Southern Hemisphere observers are gaining light.
Sky Highlight
Ophiuchid meteor shower remnants add low-level activity in mid-August nights, but the sky is between major showers. This is a good period for deep-sky observing from both hemispheres, as moonless nights in mid-August offer stable, often transparent skies.
Deep Sky Object
M9, a globular cluster in Ophiuchus, is one of the closest globular clusters to the galactic center, lying roughly 25,800 light-years away. It sits in a dense Milky Way field and is best seen from southern latitudes where Ophiuchus rises higher, though it is accessible from mid-northern latitudes as well.
Featured Star
Sabik, the eta Ophiuchi binary, pairs two nearly identical white stars (an A2V and an A3V) in a mutual orbit with a period of approximately 88 years, sitting about 88 light-years from Earth. The coincidence of distance and period in round numbers is one of those numerical accidents that makes stellar catalogs oddly satisfying to read.
Around This Date
- August 18, 1877Asaph Hall observed Phobos for the first time, noting its exceptionally rapid orbital period of just under eight hours, faster than Mars itself rotates, making Phobos rise in the west and set in the east as seen from the Martian surface.
- August 22, 2003NASA's Spitzer Space Telescope launched from Cape Canaveral, beginning a sixteen-year mission that fundamentally changed infrared astronomy and revealed star-forming regions, exoplanet atmospheres, and distant galaxies previously hidden from view.
Two stars that match each other so closely they spend 88 years walking in circles together, stellar companionship at a geological pace.