M13

From South Dublin Astronomical Society

M13
Type	Globular cluster
NGC	NGC 6205
Constellation	Hercules
Right Ascension	16h 41.7m
Declination	+36° 28’
Magnitude	5.9
Size	17 arc min.
Image:M13 messier image.jpg {{{imgnote}}}

A third of the way along a line joining Eta and Zeta Herculis is M13, one of the finest globular clusters north of the Celestial Equator. Binoculars will show a nice spot of grainy light with two equally bright stars either side of the cluster. Keep Eta at the top edge of your binocular field and it’s a cinch to spot this swarm of possibly a million ancient suns. Look just to the east of the globular and you’ll see a nice chain of stars; the westernmost is the brightest while the rest are strung out to give the appearance of a lazy comet tail. Your sky explorations will turn up many of these chance arrangements of stars adjacent to deep-sky highlights. Edmond Halley discovered M13 in 1714 and noted that ‘it shows itself to the naked eye when the sky is serene and the Moon absent.’ The combined light of it’s myriad suns translates to that of a 6th magnitude “star”. M13 is 25,100 light-years away and measures 145 light-years from edge to edge.