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Sunday, February 19, 2017

M3, Globular Cluster in Canes Venatici

Did you see that fuzzy globe in the lower left corner of the sketch? It is M3, also catalogued as NGC5272, a globular cluster located in the constellation of Canes Venatici (CVn). Cor Caroli, the alpha star in CVn is visible with the naked eyed even from severely light polluted skies but when the light pollution washes out the dim stars, Cor Caroli lies solitary between the constellations of Bootes and Ursa Major.
M3 is one of the brightest globular clusters in the sky, but it does not look like much in the sketch. Just another fuzzy cottonish smudge. Why? Light pollution is the first reason, but also low magnification. Even from darker skies, M3 as seen with low magnification  looks like a tight snowball with some fuzz around it.

It seems very dissapointing to look at one of brightest objects in the sky and not be able to see it well, right? But these are some facts that will make the view more exciting: it is located at 33900 Ly from us and contains an estimated half million stars. Its mass is around 800.000 solar mases because part of its stars are “invisible” because they have evolved into white dwarf stars of neutron stars. The most impressive fact about this cluster is that half of its mass is packed in a spheric space of 22 light years in diameter. That of course is a lot of space so they aren’t near each other, but way closer than the distance between our planet and the second nearest star (the first one is the sun) Proxima Centauri, which is at more than 4 light years from us.

Still not impress? Well, it is time to get to darker skies and push the magnification with the help of a telescope.  In my 150mm of aperture, at 37.5x the core still looks like a smowball, but once I doubled that magnification it started to reveal some granular texture in the core sorrounded by a  nebulous fuzz.  I kept pushing the magnification to 100x and then got the best view. A perfect combination of detail, sharpness and field of view. The core remained granulated but some stars outside the core could be resolved with averted vision. I counted about 20, but much more kept appearing as others were dissapearing, like if it was made of glitter fabric.  I tried my best to show in a sketch all that show, but it won’t be as good as the true view. M3 it is definitely a fantastic  show worth travel plan to dark skies with a telescope. 

Thanks for reading,


Edited by: Jennifer Steinberg (editor in chief)



  1. Nice post. I may have to invest in some binoculars some time. Never thought of that.Great article! Keep up the spacial and intersteller work.
    Bless you,
    Robert M. Doyle

  2. Sorry,interstellar,not intersteller

  3. Excelente dibujo mi amigo !!! Es un hermoso cúmulo y lo retrataste tal cual se ve. Siempre un gusto pasar por tu blog. De paso me pongo canchero con el inglés ja. Saludos !