May 30
The Heart Rises Higher
Sun Position
The Sun is in Gemini at about +21.7° declination, very near its maximum northern excursion. Northern Hemisphere nights are brief; southern nights are long and cold, winter observing at its best for those equipped for it.
Sky Highlight
Antares is now well clear of the horizon by 11 PM for southern observers and just reaching a useful altitude for mid-northern viewers. Scorpius as a whole sprawls across the southeastern sky for southern and equatorial observers, offering M4, M6, M7, M80, and M62 all within a single constellation, one of the most globular-cluster-rich regions accessible to the eye.
Deep Sky Object
M7 (NGC 6475), open cluster in Scorpius, about 980 light-years away. One of the most prominent open clusters in the sky, visible to the naked eye as a distinct patch near the scorpion's tail. Ptolemy recorded it in the second century CE. At its distance, individual stars are easily resolved in binoculars; it's too large for most telescope fields. Best from southern and equatorial latitudes.
Featured Star
Antares (α Scorpii) concludes this trio of appearances, a red supergiant 550 light-years away, spectral class M1.5Iab-b. Its diameter is so large that if it replaced the Sun, its surface would extend past the orbit of Mars. It is embedded in a faint nebula formed partly from its own shed outer layers, visible in long-exposure photographs as a pale reddish glow around the star.
Around This Date
- May 30, 1966Surveyor 1 landed softly on the Moon and began transmitting photographs from the lunar surface, the first American spacecraft to achieve a soft landing on another world.
- May 30, 1971NASA launched Mariner 9 from Cape Canaveral; it became the first spacecraft to orbit another planet, arriving at Mars in November 1971 and mapping over 85 percent of its surface.
A red supergiant in its own fog: the biggest stars are the messiest.