Topline<\/p>\n
Two green comets<\/a> \u2014 Lemmon (C\/2025 A6)<\/a> and SWAN (C\/2025 R2) \u2014 are becoming visible from the Northern Hemisphere in binoculars or a small telescope. They\u2019ll get brighter next week as the moon recedes from the evening sky, and around Oct. 20-23 as the Orionid meteor shower<\/a> peaks, but Comet Lemmon in particular is now being widely observed. Here\u2019s how to find them on Saturday, Oct. 11, 2025. <\/p>\n Comet C\/2024 G3 (Atlas) reflects on a puddle on a dirt road near Firmat, Argentina. (Photo by Patricio Murphy\/NurPhoto via Getty Images)<\/p>\n NurPhoto via Getty ImagesKey Facts<\/p>\n On Saturday, Comet Lemmon will be visible before sunrise in the northeast, close to the Big Dipper, while a 76%-lit waning gibbous moon shines in the west. Dimmer Comet SWAN will be low in the southwest after sunset.<\/p>\n Comets Lemmon and SWAN are the first comets visible in binoculars since Comet Tsuchinshan-ATLAS in October 2024 \u2014 though it\u2019s Comet Lemmon that\u2019s brighter. <\/p>\n Comet Lemmon has been getting steadily brighter in recent days. Last in the inner solar system around the year 675, its following visit will take place around 3175. Comet SWAN is a much longer-period comet, taking about 22,554 years to orbit the sun. It won\u2019t visit again until 24,579. <\/p>\n Both comets will appear as small, diffuse patches in a pair of binoculars that change position slightly each day. By early next week, Comet Lemmon will also be visible in the post-sunset night sky. <\/p>\n Over the next two weeks, both comets are forecast to become brighter as the moon departs from the night sky and they both reach their closest to Earth around Oct. 20-23.<\/p>\n A finder chart for Comet Lemmon for Oct. 11, 2025, and for the following two weeks, courtesy from In-The-Sky.org.<\/p>\n In-The-Sky.com (used with permission)Comet Lemmon: When And Where To Find It On Saturday, Oct. 11, 2025<\/p>\n Distance from the sun: 76.8 million miles (123.6 million kilometers)<\/p>\n Distance from Earth: 68.3 million miles (109.9 million kilometers)<\/p>\n On Saturday, Oct. 11, 2025, Comet Lemmon will be visible in the northeast before dawn to the right-hand side of the Big Dipper, low in the sky but observable in binoculars. It will be roughly halfway between the stars Megrez and Phecda on the inside of the Big Dipper’s bowl, and Alula Borealis and Alula Australis, two bright stars that mark the foot of the constellation Ursa Major, \u201cthe Great Bear,\u201d according to finder charts on In-The-Sky.com<\/a>. <\/p>\n Comet Lemmon: When And Where To Find It On Saturday, Oct. 11, 2025 <\/p>\n StellariumComet Lemmon: Best Time To Look<\/p>\n The best time to look for Comet Lemmon will be a 30-minute window beginning about 90 minutes before sunrise where you are<\/a>. For New York City, sunrise is 7:03 a.m. EDT, so the ideal viewing time will be 5:33-6:03 a.m. EDT (Venus will rise in the east during this time), although you can look earlier. The comet’s height above the horizon will vary depending on your location, but from New York, it will be around 27 degrees up (about the width of the span of your hand, with fingers stretched out, held at arm’s length) and rising. In addition to fighting the increasing light of dawn, on Thursday, there’s also the light of the 76%-lit waning gibbous moon, setting in the west, to contend with.<\/p>\n A finder chart for Comet SWAN R2 for Oct. 11, 2025, and for the following two weeks, courtesy from In-The-Sky.org.<\/p>\n In-The-Sky.com (used with permission)Comet Swan: When And Where To Find It On Saturday, Oct. 11, 2025<\/p>\n Distance from the sun: 77.6 million miles (124.9 million kilometers)<\/p>\n Distance from Earth: 29.1 million miles (46.9 million kilometers)<\/p>\n Blueish-green Comet SWAN \u2014 only discovered in September \u2014 will be visible in binoculars on Saturday, Oct. 11, 2025, low in the southwest after sunset, to the upper-right side of bright star Antares in the constellation Scorpius, according to finder charts on In-The-Sky.com<\/a>.<\/p>\n Comet SWAN: When And Where To Find It On Saturday, Oct. 11, 2025 <\/p>\n StellariumComet Swan: Best Time To Look<\/p>\n The best time to look for Comet SWAN will be a 30-minute window beginning about 90 minutes after sunset where you are. For New York City, sunset is 6:19 p.m. EDT, so the ideal viewing time will be 7:49-8:19 p.m. EDT. The comet’s height above the horizon will vary depending on your location, but from New York, it will be around 15 degrees up (about the width between your little finger and forefinger held at arm’s length) and sinking.<\/p>\n Why Both Comets Are Green<\/p>\n Recent photographs show both comets to be glowing a distinctive green. This color comes from a molecule called dicarbon (C\u2082), which fluoresces green when broken apart by sunlight in a comet\u2019s coma. According to NASA<\/a>, the green glow is confined to the comet\u2019s head because the molecule quickly breaks down and doesn\u2019t reach the tail. This makes Lemmon and SWAN look striking in long-exposure photographs, even if they appear fainter to the naked eye.<\/p>\n Why Comets Have Tails<\/p>\n Comets sprout tails as they near the sun. According to NASA<\/a>, heat turns surface ices into gas, forming a coma, while sunlight and the solar wind push this material outward. That creates two tails \u2014 a broad, curved dust tail that reflects sunlight and a straight, bluish ion tail that points directly away from the sun. Some tails can stretch for millions of miles and are always directed away from the sun, no matter the comet\u2019s direction of travel. <\/p>\n Check my feed<\/a> every day this month for a daily \u201ccomet tracker\u201d with finder charts and tips for viewing Comet Lemmon and Comet SWAN.<\/p>\n Further ReadingForbesComet Tracker For Thursday: It\u2019s Finally Time To See Rare Twin CometsBy Jamie Carter<\/a>ForbesA Once-In-A-Lifetime Green Comet May Soon Be Visible, Scientists SayBy Jamie Carter<\/a>ForbesSee Rare Sight Of Two Comets As Meteor Shower Peaks \u2014 Here\u2019s WhenBy Jamie Carter<\/a>ForbesComet Lemmon: Your Ultimate Viewing Guide To The \u2018Comet Of The Year\u2019By Jamie Carter<\/a>ForbesTwo Naked Eye Comets, \u2018Harvest Moon\u2019 And Fireballs: October\u2019s Night SkyBy Jamie Carter<\/a>ForbesOrionid Meteor Shower Begins Thursday \u2014 When To See It At Its Best With Two CometsBy Jamie Carter<\/a>ForbesI Just Saw And Photographed The Comet \u2014 Here\u2019s How You Can TooBy Jamie Carter<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Topline Two green comets \u2014 Lemmon (C\/2025 A6) and SWAN (C\/2025 R2) \u2014 are becoming visible from the…\n","protected":false},"author":2,"featured_media":492251,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[160621,160622,160620,160626,160627,158533,160625,70,160623,16,15,160624,160628],"class_list":{"0":"post-492250","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-c-2025-a6-lemmon","9":"tag-c-2025-r2-swan","10":"tag-comet-lemmon","11":"tag-comet-of-the-year","12":"tag-comet-tonight","13":"tag-green-comets","14":"tag-october-2025-comets","15":"tag-science","16":"tag-swan-r2","17":"tag-uk","18":"tag-united-kingdom","19":"tag-where-is-the-comet","20":"tag-where-to-see-the-comet"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/115358285531324077","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/492250","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=492250"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/492250\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/492251"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=492250"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=492250"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=492250"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}