June 5
Head of the Healer
Sun Position
The Sun is in Gemini, declination around +22.5°. Northern summer days are near their maximum length; Southern Hemisphere observers are deep into winter nights.
Sky Highlight
June 5 or 6 marks the date of a Transit of Venus when one occurs in this century's cycle (most recently June 5–6, 2012). No transit falls today in most years, but on rare occasions this date witnesses Venus crossing the solar disk, an event so infrequent that most observers see it only once in a lifetime.
Deep Sky Object
M12 (NGC 6218), a globular cluster about 16,000 light-years away. M12 in Ophiuchus is slightly larger and more loosely packed than its neighbor M10, giving it an open, granular texture through a telescope; recent studies suggest it may have lost a large fraction of its low-mass stars to tidal stripping. Well-placed for both hemispheres through June evenings; binoculars reveal a fuzzy spot, a telescope resolves the outer halo.
Featured Star
Rasalhague (α Oph) is a white giant (A5III) about 47 light-years away, the brightest star in Ophiuchus; its Arabic name means 'head of the snake-charmer.' It marks the top of the figure that stands between Scorpius and Sagittarius in the zodiac's unofficial thirteenth constellation.
Around This Date
- June 5–6, 2012The last Transit of Venus of the 21st century was observed worldwide, the second of a pair that began in 2004; the next transit will not occur until December 2117.
- June 3, 1769James Cook observed the 1769 Transit of Venus from Tahiti, providing measurements that contributed to a reliable calculation of the Earth-Sun distance.
The healer's head rises in the east, bright enough to find without a map.