{"id":35329,"date":"2022-08-11T00:00:00","date_gmt":"2022-08-11T00:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?post_type=purple_issue&p=35329"},"modified":"2022-09-12T11:13:09","modified_gmt":"2022-09-12T11:13:09","slug":"glorious-globulars","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2022\/08\/11\/glorious-globulars\/","title":{"rendered":"Glorious globulars"},"content":{"rendered":"\n

From fuzzy blobs to star cities, Paul Money <\/strong>takes us on a tour of 15 of the best globular clusters to observe in this season\u2019s night skies<\/p>\n\n

\"\"
Glittering ball of stars M92, often overlooked in favour of its glitzier neighbour M13, is in our rundown of the most stunning globular clusters to observe <\/figcaption><\/figure>\n\n

Fuzzy blobs \u2013 that\u2019s often what new stargazers viewing a globular cluster think when they spot their first one. It\u2019s true that these concentrations of ancient stars, ranging in number from tens of thousands to millions, can be a bit lacking in their visual impact with smaller instruments, not quite resembling the stunning images you\u2019ll regularly see online or in our Gallery section. Yet, with care, a little more aperture, and yes, by capturing the objects with an astrophoto, a globular cluster\u2019s own \u2018personality\u2019 \u2013 the detail that makes them interesting and enjoyable to view \u2013 shines through. <\/p>\n\n

All about globulars <\/strong><\/h4>\n\n

You could argue that the first globular cluster seen was Omega Centauri, listed by Johann Bayer in his Uranometria <\/em>in 1603. But that very designation belies the fact it was visible to the naked eye and considered a star. The first globular defined as a \u2018nebula\u2019 was accidentally discovered by the German amateur astronomer Abraham Ihle in 1665, one we now know as M22 in Sagittarius. More were quickly discovered, but their nature was still not properly understood. They were still described as nebulous patches or round spots of cloud until 1764, when Charles Messier resolved stars in M4. <\/p>\n\n

William Herschel coined the term \u2018globular cluster\u2019 in 1786, when he found he could resolve the objects into clouds of stars. Herschel\u2019s revelation may stem not just from his visual acuity but from the growing apertures of the instruments at his disposal, mainly reflectors he produced himself. <\/p>\n\n

Globulars form a halo around the Milky Way, centred on one side of the sky, close to the Sagittarius\u2013Scorpius border. Observing them, Harlow Shapley used a type of variable star known as RR Lyrae stars to estimate their distances in 1914. Then, noting the clusters\u2019 distribution in 1918, he established a startling and vastly larger size for the Milky Way than was commonly accepted, along with the conclusion that the galactic centre lay in Sagittarius. <\/p>\n\n

Today, globular clusters have been observed around all types of galaxies. Their origin is still up for debate, though one theory is that they formed in areas where the interstellar medium was particularly concentrated at an early epoch of the Universe. <\/p>\n\n

Sometimes even older than the galaxy they surround, their stars are typically \u2018metal poor\u2019, or lacking elements heavier than hydrogen and helium. To date, it is thought that globulars are not environments suitable for planetary formation, due to the lack of these elemental building blocks and the density of stars within them. <\/p>\n\n

Despite their reputation as mere fuzzy blobs, globular clusters can range from tight, condensed cores to more loosely confined spheres of stars. They can be slightly flattened, have outer halos of fainter stars, curved trails of stars, coloured stars and dark features, which can be seen visually and photographically. <\/p>\n\n

Globular clusters are enchanting objects if examined carefully with larger apertures. So come with us as we explore 15 of the most rewarding of these \u2018star cities\u2019 to observe in early autumn skies. <\/p>\n\n

1. Messier 3 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 5272 <\/p>\n\n

Constellation: <\/strong>Canes Venatici <\/p>\n\n

Magnitude: <\/strong>+6.3 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

M3 is one of the most scientifically studied of all globular clusters as it is unusual in being more metal-rich than most. In binoculars it is a hazy patch, while 4-inch refractors or 6-inch reflectors begin to show some of its stars. You may note that there is a central concentration and a hazy outer region, with the cluster standing out as lying inside a triangle of stars. Indeed the presence of the cluster turns the triangle into a \u2018Y\u2019. To locate M3, take a line from Arcturus in Bo\u00f6tes and extend it to Cor Caroli in Canes Venatici. M3 is just short of halfway between the two stars.<\/span><\/p>\n\n

2. Rose Cluster <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>M5, NGC 5904 <\/p>\n\n

Constellation: <\/strong>Serpens<\/p>\n\n

Magnitude: <\/strong>+5.6 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

M5 is technically a naked-eye object at magnitude +5.6 but it does require good vision and dark skies to see. It can be found close to the magnitude +5.0, naked-eye star 5 Serpentis, so if you can see a small \u2018cloud\u2019 next to this star, then you have it. In larger apertures, such as an 8-inch reflector, M5 has a compact core that is quite bright and has notable trails of stars that seem to curve and stream away from the centre, viewable with averted vision. <\/p>\n\n

3. Messier 10 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6254 <\/p>\n\n

Constellation: <\/strong>Ophiuchus <\/p>\n\n

Magnitude: <\/strong>+6.6 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor<\/p>\n\n

From a dark-sky site, M10 is an easy binocular target with a nearby companion globular, M12, the Gumball. M10 is located close to the magnitude +4.8 star 30 Ophiuchi, which is distinctly orange and hard to miss. M10 is round and brightens gradually towards its core, which some observers suggest looks pear-shaped. Averted vision helps to bring out a faint halo of stars surrounding the core, while larger telescopes hint at a couple of star trails extending away from it.<\/span><\/p>\n\n

4. Gumball Globular Cluster <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>M12, NGC 6218 <\/p>\n\n

Constellation: <\/strong>Ophiuchus<\/p>\n\n

Magnitude: <\/strong>+6.7 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor<\/p>\n\n

The Gumball is marginally fainter than its nearby companion M10 but that doesn\u2019t make it hard to find. This globular, M10 and 30 Ophiuchi can all be seen in the same 10×50 binocular field of view.<\/span> M12 and M10 both lie at a similar distance from us and are genuine neighbours in space.<\/span> An 8-inch reflector begins to resolve the Gumball as a loose core surrounded by a hazy halo of stars. With larger apertures, a dark V-like shape cuts into the core.<\/span><\/p>\n\n

5. Messier 14 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6402 <\/p>\n\n

Constellation: <\/strong>Ophiuchus <\/p>\n\n

Magnitude: <\/strong>+7.6 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

M14 is sometimes overlooked, yet it is a rewarding object. Find it with the help of the triangle shape it forms with Beta (\u03b2) Ophiuchi, Cebalrai and Nu (\u03bd) Ophiuchi. M14 is the apex pointing towards M10. It is smaller than M10 and fainter, but quite compact. With greater magnification and aperture, a faint outer halo of stars comes into view. <\/p>\n\n

\"\"
Where to find our 15 glorious globular clusters in early autumn skies. The chart shows the view at 22:00 BST (21:00 UT) on 15 September <\/figcaption><\/figure>\n\n

6. Messier 9 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6333 <\/p>\n\n

Constellation: <\/strong>Ophiuchus <\/p>\n\n

Magnitude: <\/strong>+7.8 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

M9 is an oddball of a globular cluster \u2013 small and compact, yet dimmer than you might expect. Like M14, this could be due to several dark clouds in the vicinity that may be supressing the light of the cluster. There is little in the way of remarkable features here, but stick with it as larger apertures hint at a slightly oval core with a couple of curved stellar lines extending out from its edge. <\/p>\n\n

7. Great Globular Cluster <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>M13, NGC 6205 <\/p>\n\n

Constellation: <\/strong>Hercules <\/p>\n\n

Magnitude: <\/strong>+5.8 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

Probably the best-known globular in the Messier Catalogue, M13 is easy to locate between the two main stars forming the western side of the \u2018Keystone\u2019 of Hercules, Eta (\u03b7) and Zeta (\u03b6) Herculis, with two 7th-magnitude stars flanking it. Keen naked-eye observers may spot it under good dark skies, while binoculars will show a bright hazy glow. With largeraperture telescopes and more magnification M13 becomes alive with stars that can be resolved right to the core, making this one of the most attractive globulars in the Northern Hemisphere sky. Look out for the dark \u2018propeller\u2019 feature, as well as several curves of stars that really bring it to life. <\/span><\/p>\n\n

8. Messier 92 <\/strong><\/h4>\n\n
\"\"<\/figure>\n\n

Catalogue number: <\/strong>NGC 6341 <\/p>\n\n

Constellation: <\/strong>Hercules <\/p>\n\n

Magnitude: <\/strong>+6.5 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor<\/p>\n\n

M92 gets overshadowed by its brighter, flashier neighbour, M13, but don\u2019t let that put you off. If it were anywhere else it would be a showpiece. To find it, take a line from Eta (\u03b7) to Iota (\u03b9) Herculis and you will find this fuzzy blob awaiting discovery. It is a little more compact than M13 and, to some observers, a little extended in the north-south axis. Its fainter outer halo also has a slightly asymmetric shape. <\/p>\n\n

9. Messier 56 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6779 <\/p>\n\n

Constellation: <\/strong>Lyra <\/p>\n\n

Magnitude: <\/strong>+8.4 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

M56 is another of the less visited globulars, a result of its proximity to the Ring Nebula, M57, which lies nearby. M56 can be found on a line from Gamma (\u03b3) Lyrae to Albireo, Beta (\u03b2) Cygni. It is a softly glowing haze that isn\u2019t very compact at all, yet the few brightish stars scattered across its disc add to its charm. Its shape is quite asymmetric and its core is not a particularly strong component, but there are hints of stellar streams racing away from the centre.<\/span><\/p>\n\n

10. Messier 71 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6838 <\/p>\n\n

Constellation: <\/strong>Sagitta <\/p>\n\n

Magnitude: <\/strong>+8.2 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

M71 is easy to find, midway between Delta (\u03b4) and Gamma (\u03b3) Sagittae. For several years it was debated whether it is a dense open cluster or loose globular cluster. The debate has been settled in favour of it being a globular, relatively close to us in space. Because of its looseness, there is no dense core apparent, but star trails and dark lines do seem evident. M71\u2019s overall shape resembles a \u2018Y\u2019.<\/span><\/p>\n\n

11. Great Sagittarius Cluster <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>M22, NGC 6656 <\/p>\n\n

Constellation: <\/strong>Sagittarius <\/p>\n\n

Magnitude: <\/strong>+5.2 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

Northeast of Lambda (\u03bb) Sagittarii, this globular is the closest to Earth and the brightest on our list. Only the Southern Hemisphere\u2019s Omega Centauri and 47 Tucanae are brighter. If it was higher in the sky for Northern Hemisphere viewers, M22 might top our rankings. A glorious globe of stars that binoculars reveal as a nebula, it becomes starry in 6-inch scopes. Slightly oval with a faint outer halo, a dark lane through the core adds to its splendour.<\/span><\/p>\n\n

12. Messier 28 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 6626 <\/p>\n\n

Constellation: <\/strong>Sagittarius <\/p>\n\n

Magnitude: <\/strong>+6.9 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

M28 is another of those underappreciated globulars that has been overshadowed by a nearby neighbour, in this case M22. It lies just northwest of Lambda (\u03bb)<\/span> Sagittarii, and so all three objects can be seen together in the same binocular view. M28 has a compact core with a faint halo and can appear slightly elongated.<\/span> Indeed in his book <\/span>The <\/em>Messier <\/em>Album, <\/em>astronomer John Mallas describes it as \u201clooking like a cucumber.\u201d<\/span><\/p>\n\n

13. Jellyfish Cluster <\/strong><\/h4>\n\n
\"\"<\/figure>\n\n

Catalogue number: <\/strong>M30, NGC 7099 <\/p>\n\n

Constellation: <\/strong>Capricornus <\/p>\n\n

Magnitude: <\/strong>+7.2 <\/p>\n\n

Minimum equipment: <\/strong>8-inch reflector; 4-inch refractor <\/p>\n\n

The Jellyfish lies close to the star 41 Capricorni and on a line with Zeta (\u03b6) Capricorni. It is in a retrograde orbit about the inner halo of the Milky Way and is undergoing core collapse. Some indications suggest it was not formed in our Galaxy but may be captured from a satellite galaxy. It has a very compact core with a halo and needs moderate to large apertures to resolve its stars. <\/p>\n\n

14. Messier 2 <\/strong><\/h4>\n\n
\"\"<\/figure><\/div>\n\n

Catalogue number: <\/strong>NGC 7089 <\/p>\n\n

Constellation: <\/strong>Aquarius<\/p>\n\n

Magnitude: <\/strong>+6.6 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

M2 lies almost a third of the way between Beta (\u03b2) Aquarii and Epsilon (\u03b5) Pegasi and is easily visible in binoculars as a smudge of light. It appears dense with a fainter halo and a 10th-magnitude star to its northeast. An interesting feature of M2 is a dark lane or line curving through the outer part of the core to the northeast, which is visible to both visual observers and imagers.<\/span> A regular watch of this globular cluster will reveal the varying brightness of a prominent RR Lyrae star, which fluctuates from mag. +12.5 to +14.0 over a period of 11 days. It is located on M2\u2019s eastern side, just north of the centre.<\/span><\/p>\n\n

15. Great Pegasus Cluster <\/strong><\/h4>\n\n
\"\"<\/figure>\n\n

Catalogue number: <\/strong>M15, NGC 7078 <\/p>\n\n

Constellation: <\/strong>Pegasus <\/p>\n\n

Magnitude: <\/strong>+6.3 <\/p>\n\n

Minimum equipment: <\/strong>6-inch reflector; 3-inch refractor <\/p>\n\n

M15 can be found as a fuzzy blob 4\u02da to the northwest of Epsilon (\u03b5) Pegasi and appears as an impressive smudge in binoculars. Larger-aperture scopes show it as quite dense and brightening rapidly towards the centre, with an uneven faint halo surrounding it. On the northeast edge of the core there is a dark patch and a further test of observing skills lies in resolving the faint, spidery \u2018arms\u2019 of stars that stretch out from the centre. M15 has over 100 variable stars, which are mainly RR Lyrae variables, and one faint planetary nebula, Pease 1, which is a challenge for large-aperture instruments.<\/span><\/p>\n\n

<\/p>\n\n

\n\n
\"\"<\/figure><\/div>\n\n

Paul Money is an astronomy writer and broadcaster, and the reviews editor of BBC Sky at Night Magazine<\/p>\n\n

<\/p>\n\n

<\/p>\n\n

<\/p>\n\n

Photos: BERNHARD HUBL\/CCDGUIDE.COM\/ FRANZ KLAUSER\/ MANFRED WASSHUBER\/CCDGUIDE.COM, MICHAEL BREITE\/STEFAN HEUTZ\/WOLFGANG RIES\/CCDGUIDE.COM, BERNHARD HUBL\/CCDGUIDE.COM X 3, CEDIC TEAM\/BERNHARD HUBL\/CCDGUIDE.COM, DANIEL VERSCHATSE\/CCDGUIDE.COM\/ FRANZ KLAUSER\/CCDGUIDECOM, G\u00dcNTER KERSCHHUBER\/CCDGUIDECOM, DANIEL VERSCHATSE\/ CCDGUIDECOM, BERNHARD HUBL\/ CCDGUIDECOM X 4, CHART BY PETE LAWRENCE<\/p>\n","protected":false},"excerpt":{"rendered":"

Join us for our tour of 15 of the best globular clusters to observe in this season\u2019s night skies<\/p>\n","protected":false},"author":24,"featured_media":35311,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ub_ctt_via":"","purple_page_number":"60","purple_custom_meta_purple_page_number":"60","purple_seq_number":"1","purple_custom_meta_purple_seq_number":"1","purple_source_article":"article_60-1.xml","purple_custom_meta_purple_source_article":"article_60-1.xml","purple_source_issue":"September-2022","purple_custom_meta_purple_source_issue":"September-2022","purple_external_id":"September-2022-60-1","purple_custom_meta_purple_external_id":"September-2022-60-1","purple_issue_code":"|0000086556||","purple_custom_meta_purple_issue_code":"|0000086556||","purple_android_product":"com.im.skyatnight.208","purple_custom_meta_purple_android_product":"com.im.skyatnight.208","purple_ios_product":"com.im.skyatnight.208","purple_custom_meta_purple_ios_product":"com.im.skyatnight.208","purple_web_product":"","purple_custom_meta_purple_web_product":"","purple_publication_id":"075fab74-0a21-4201-866a-899d6c41c40c","purple_migrated":"","kt_blocks_editor_width":""},"categories":[21],"tags":[14],"featured_image_src":"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f.jpg","author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"acf":{"readingTimeMinutes":"12","apple_news_title":""},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f.jpg",1751,2048,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f-256x300.jpg",256,300,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f-768x898.jpg",768,898,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f-876x1024.jpg",800,935,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f-1313x1536.jpg",1313,1536,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2022\/08\/271b66af-52bf-438e-8bf8-e492dea87f1f.jpg",1751,2048,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"Join us for our tour of 15 of the best globular clusters to observe in this season\u2019s night skies","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/35329"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/comments?post=35329"}],"version-history":[{"count":15,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/35329\/revisions"}],"predecessor-version":[{"id":35810,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/35329\/revisions\/35810"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/35311"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=35329"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=35329"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/tags?post=35329"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}