{"id":791543,"date":"2024-11-28T06:25:00","date_gmt":"2024-11-28T11:25:00","guid":{"rendered":"https:\/\/spaceweekly.com\/?p=791543"},"modified":"2024-11-28T06:25:00","modified_gmt":"2024-11-28T11:25:00","slug":"comets-are-icy-balls-of-gas-dust-and-rock","status":"publish","type":"post","link":"https:\/\/spaceweekly.com\/?p=791543","title":{"rendered":"Comets are icy balls of gas, dust and rock"},"content":{"rendered":"<p> <br \/>\n<\/p>\n<div>\n<figure id=\"attachment_490266\" aria-describedby=\"caption-attachment-490266\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><figcaption id=\"caption-attachment-490266\" class=\"wp-caption-text\">View at EarthSky Community Photos. | Makrem Larnaout in Tunisia captured Comet A3 on October 15, 2024, when the globular cluster M5 was within view. Thank you, Makrem! Read more about comets below.<\/figcaption><\/figure>\n<h3>What are comets?<\/h3>\n<p>Comets are icy balls of gas, dust and rock that orbit the sun. Astronomers believe most comets are leftovers from the formation of the sun and planets. In fact, comets come from the farthest reaches of the solar system, including the Kuiper Belt and the Oort Cloud. When passing stars outside our solar system jostle comets, the comets begin the long trek inward toward the sun. Then, as they come close to the sun and heat up, they release gas in a process called <em>outgassing<\/em>. This creates the long, glowing tail that stretches behind the comet and points away from the sun.<\/p>\n<p>The 2025 EarthSky lunar calendar makes a great gift. Get yours today!<\/p>\n<h3>The experts on comets<\/h3>\n<p><iframe loading=\"lazy\" title=\"Comets | Meet the experts\" width=\"1110\" height=\"624\" src=\"https:\/\/www.youtube.com\/embed\/WaKXl0NQ4Zk?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>The video above is from the Meet the Experts series of the European Space Agency (ESA). In it, comet scientist Charlotte Goetz, formerly of ESA, discusses comets, their formation and their study. Also, she explains that comet nuclei are relatively small \u2013 about the size of a small earthly town \u2013 and that they are loosely packed balls of ice and dust.<\/p>\n<p>Moreover, the comets we know about are mostly potato-shaped, but some are more oddly shaped. In addition, it\u2019s only when comets come near the sun that they heat up and spew dust and gases. In fact, they develop giant glowing heads \u2013 called a comet\u2019s coma \u2013 that may be larger than most planets. And indeed, they sprout their long comet tails that stretch millions of miles long.<\/p>\n<p>NASA says that the current number of known comets is 3,979.<\/p>\n<h3>The parts of a comet<\/h3>\n<p>The <em>nucleus<\/em> is the core of a comet. Additionally, it is also the <em>head<\/em> of the comet. When a comet nears the sun and heats up, some of its frozen surfaces begin to thaw and create the fuzzy <em>coma<\/em> that surrounds the nucleus.<\/p>\n<p>Surprisingly, a comet can have two tails. The <em>ion tail<\/em> is generally bluish in color and points away from the sun because it\u2019s blown back by the solar wind. The ion tail is made of \u2013 you guessed it \u2013 ions. These are electrically charged gas molecules. The second tail is the <em>dust tail<\/em>. It is indeed made of dust and normally has a whiter appearance. The dust tail forms a slightly curved trail behind the path of the comet.<\/p>\n<figure id=\"attachment_418316\" aria-describedby=\"caption-attachment-418316\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/earthsky.org\/upl\/2020\/09\/parts-of-a-comet-NASA.jpg\" alt=\"Diagram of a comet with labels for parts.\" width=\"800\" height=\"565\" class=\"size-full wp-image-418316\" srcset=\"https:\/\/earthsky.org\/upl\/2020\/09\/parts-of-a-comet-NASA.jpg 683w, https:\/\/earthsky.org\/upl\/2020\/09\/parts-of-a-comet-NASA-300x212.jpg 300w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\"\/><figcaption id=\"caption-attachment-418316\" class=\"wp-caption-text\">Artist\u2019s concept of the parts of a comet. Image via NASA.<\/figcaption><\/figure>\n<h3>Observing comets<\/h3>\n<p>Us skywatchers are, of course, most interested in comets when they appear as (sometimes unexpected, often greenish) visitors in our skies. Since comets are most active when they\u2019re near the sun, we tend to see comets shortly after sunset or before sunrise. At such times, comets don\u2019t sweep across the skies as meteors do. But they do move slowly, from night to night, in front of the stars. They can be very beautiful, especially in a dark sky. <\/p>\n<figure id=\"attachment_450219\" aria-describedby=\"caption-attachment-450219\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/earthsky.org\/upl\/2023\/09\/Comet-C-2023-P1-Nishimura-Alan-Howell-Sep-4-2023-e1693864511400.jpeg\" alt=\"Dark sky with a few stars, small fuzzy green orb and a long, thin, faint greenish tail.\" width=\"800\" height=\"500\" class=\"size-full wp-image-450219\" srcset=\"https:\/\/earthsky.org\/upl\/2023\/09\/Comet-C-2023-P1-Nishimura-Alan-Howell-Sep-4-2023-e1693864511400.jpeg 800w, https:\/\/earthsky.org\/upl\/2023\/09\/Comet-C-2023-P1-Nishimura-Alan-Howell-Sep-4-2023-e1693864511400-300x188.jpeg 300w, https:\/\/earthsky.org\/upl\/2023\/09\/Comet-C-2023-P1-Nishimura-Alan-Howell-Sep-4-2023-e1693864511400-768x480.jpeg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\"\/><figcaption id=\"caption-attachment-450219\" class=\"wp-caption-text\">View at EarthSky Community Photos. | Alan Howell of Greensboro, North Carolina, captured this image on September 4, 2023. He wrote: \u201c3rd time is the charm! I was finally able to capture our newest comet, C\/2023 P1 Nishimura, around 5:30 a.m. today just before the sunrise washed out the tail. What a spectacular sight to see this rare green beauty show up on my camera screen!\u201d Thank you, Alan.<\/figcaption><\/figure>\n<p>Recently, many enjoyed Comet A3 Tsuchinshan-ATLAS in the evening sky. When will the next bright comet appear? Only time will tell.<\/p>\n<p>Bottom line: Comets are diffuse balls of ice and dust orbiting the sun. They\u2019re sometimes visible in our skies. A comet\u2019s tail may stretch millions of miles across space.<\/p>\n<p>Via ESA<\/p>\n<p>Via NASA<\/p>\n<p><span class=\"cp-load-after-post\"\/><\/div>\n<div>\n<div class=\"post-author\">\n<h4>Editors of EarthSky<\/h4>\n<p>                    View Articles\n                  <\/p><\/div>\n<div class=\"post-tags\">\n<h6 data-udy-fe=\"text_7c58270d\">About the Author:<\/h6>\n<p>The EarthSky team has a blast bringing you daily updates on your cosmos and world.  We love your photos and welcome your news tips.  Earth, Space, Sun, Human, Tonight. Since 1994.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<p><br \/>\n<br \/><a href=\"https:\/\/earthsky.org\/astronomy-essentials\/definition-what-are-comets\/?rand=772280\">Source link <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>View at EarthSky Community Photos. | Makrem Larnaout in Tunisia captured Comet A3 on October 15, 2024, when the globular cluster M5 was within view. Thank you, Makrem! Read more&hellip; <\/p>\n","protected":false},"author":1,"featured_media":791544,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[],"class_list":["post-791543","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earth-sky"],"_links":{"self":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/791543","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=791543"}],"version-history":[{"count":0,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/791543\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/media\/791544"}],"wp:attachment":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=791543"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=791543"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=791543"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}