August 29
Ophiuchus at the Close
Sun Position
The Sun is in Virgo at roughly +7° declination. Northern Hemisphere days are shortening at their fastest rate of the summer; the equinox is just three weeks away.
Sky Highlight
Late August delivers a transitional sky: Scorpius and Sagittarius are setting in the southwest in the early evening, while Pegasus and Andromeda are rising in the east. From both hemispheres, this week represents the cusp between the summer and autumn sky, and a long observing session can capture objects from both seasons.
Deep Sky Object
M2, one of the largest and most concentrated globular clusters in the sky, is well placed in late August and early September in Aquarius. It lies roughly 37,500 light-years away and contains perhaps 150,000 stars, with a notably dense core that is visible even in a small telescope. Accessible from both hemispheres, it rises in the southeast for northern observers and the northeast for southern observers.
Featured Star
Rasalhague, the A5III white giant 47 light-years away in Ophiuchus, is sinking toward the western sky in late August evenings, heading for seasonal invisibility. It marks the head of the serpent-bearer, a figure that holds a snake divided in two halves across the sky, Serpens Caput to the west and Serpens Cauda to the east, the only IAU constellation split into two non-contiguous parts.
Around This Date
- August 27, 1962Mariner 2 launched, and its December 1962 Venus flyby provided the first direct measurements of interplanetary space, confirming the existence of the solar wind as a continuous particle stream.
- August 28, 1993Galileo's discovery of Dactyl confirmed that asteroid satellites exist in the main belt, eventually leading to the recognition that binary and trinary asteroid systems are surprisingly common.
Ophiuchus will be out of the evening sky in a few weeks, the serpent-bearer holds the snake a little longer each year before winter takes them both below the horizon.