{"id":293,"date":"2021-08-08T17:02:01","date_gmt":"2021-08-08T14:02:01","guid":{"rendered":"https:\/\/www.lbscience.org\/en\/2025\/06\/02\/armageddon-not-today\/"},"modified":"2025-11-26T04:07:42","modified_gmt":"2025-11-26T02:07:42","slug":"armageddon-not-today","status":"publish","type":"post","link":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/","title":{"rendered":"Armageddon? Not today!"},"content":{"rendered":"

Every few months we come across headlines warning us from an asteroid that is getting dangerously close and could wipe us all out [1]. The wording is scary and deliberately alarming (click-bait), yet the panic is unwarranted: although some of us may secretly hope for such drama, the likelihood that an asteroid will exterminate humanity in the near future is very small.<\/p>\n

Still, history shows that it can happen: enormous asteroids have struck Earth and caused global catastrophes. One such impact is thought to have wiped out the dinosaurs. To gauge the risk and prepare in advance, various countries and space agencies monitor celestial objects that pass nearby. But what counts as \u201cnearby\u201d? Near what, and how near?<\/p>\n

Because distances in space are vast, measuring them in kilometers is inconvenient. Astronomers therefore defined a new unit\u2014the unsurprisingly named astronomical unit (AU). One AU equals the average distance between Earth and the Sun, roughly 151 million kilometers. An object is considered \"near\" to Earth if its orbit brings it to within 1.3 AU of the Sun [2]. In other words, any object whose path brings it within 196 million kilometers of the Sun is classified as near-Earth, and we keep track of it.<\/p>\n

Note that this definition depends only on the object\u2019s distance from the Sun, not on its distance from Earth: we draw a \u201cshell\u201d around the Sun, close (in astronomical terms) to Earth\u2019s orbit, and watch any object that enters this shell, regardless of how far it is from Earth. For example, an asteroid might reach exactly Earth\u2019s distance from the Sun, yet while the asteroid is approaching the Sun, Earth could be on the opposite side of its orbit (see Figure 1). Such an asteroid is still tagged as near-Earth, and we monitor it.<\/p>\n

\"\"

Figure 1<\/p><\/div>\n

Space agencies currently track about 26,000 objects that meet this definition [3]. Some are only a few meters to a few dozen meters in diameter, others span hundreds of meters, and a few are a kilometer or more (see Figure 2, [3]).<\/p>\n

\"\"

Figure 2<\/p><\/div>\n

Once we have observed an object, we can plot its past trajectory. Using that path and Kepler\u2019s equations of motion (see more on Kepler\u2019s laws in our articles on orbits [4, 5]), astronomers can project the object\u2019s future orbit, determine how close it will come to Earth, and estimate the probability of impact.<\/p>\n

Astronomers define a very close encounter as an approach to within 0.2 AU of Earth\u2014or less. That is, an astronomical \u201cflyby\u201d occurs when an object comes within 30 million kilometers of our planet. Does that sound close? It is roughly 100 times farther than the distance to the Moon! So when a NASA astronomer announces an upcoming encounter with an asteroid, the separation is usually several times the distance between the Earth and the Moon. True, it is not rare for a sizeable object to pass inside the lunar orbit, but even in those cases the chance of collision is still very small.<\/p>\n

Although, as we explained herein, the risk of a devastating impact is low, space agencies nevertheless prepare for the possibility that a celestial object might come too close. Contingency plans include several methods for nudging an asteroid off course. These plans do not involve assembling a crack team of oil-drillers led by Bruce Willis, but they do let us sleep soundly without fearing that the sky will fall.<\/p>\n

Illustration: Noga Denenberg<\/p>\n

Hebrew editing: Smadar Raban
\nEnglish editing: Elee Shimshoni<\/p>\n

\n

Sources and further reading:<\/strong><\/p>\n

    \n
  1. Fox29 An asteroid taller than the Empire State Building may crash into Earth<\/a><\/li>\n
  2. UN site: Monitoring near-Earth objects<\/a><\/li>\n
  3. NASA: Size distribution of near-Earth objects<\/a><\/li>\n
  4. Orbits in Space: Part I<\/a><\/li>\n
  5. Orbits in Space, Part B<\/a><\/li>\n<\/ol>\n

    \n","protected":false},"excerpt":{"rendered":"

    Every few months we come across headlines warning us from an asteroid that is getting dangerously close and could wipe us all out [1]. The wording is scary and deliberately alarming (click-bait), yet the panic is unwarranted: although some of us may secretly hope for such drama, the likelihood that an asteroid will exterminate humanity […]<\/p>\n","protected":false},"author":39,"featured_media":1609,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[3,7],"tags":[],"class_list":["post-293","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-astronomy","category-physics"],"acf":[],"yoast_head":"\nArmageddon? Not today! - Little, Big Science<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Armageddon? Not today! - Little, Big Science\" \/>\n<meta property=\"og:description\" content=\"Every few months we come across headlines warning us from an asteroid that is getting dangerously close and could wipe us all out [1]. The wording is scary and deliberately alarming (click-bait), yet the panic is unwarranted: although some of us may secretly hope for such drama, the likelihood that an asteroid will exterminate humanity […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/\" \/>\n<meta property=\"og:site_name\" content=\"Little, Big Science\" \/>\n<meta property=\"article:published_time\" content=\"2021-08-08T14:02:01+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-11-26T02:07:42+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg\" \/>\n\t<meta property=\"og:image:width\" content=\"2400\" \/>\n\t<meta property=\"og:image:height\" content=\"1350\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@DenElad\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"4 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/\",\"url\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/\",\"name\":\"Armageddon? Not today! - Little, Big Science\",\"isPartOf\":{\"@id\":\"https:\/\/www.lbscience.org\/en\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg\",\"datePublished\":\"2021-08-08T14:02:01+00:00\",\"dateModified\":\"2025-11-26T02:07:42+00:00\",\"author\":{\"@id\":\"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/82a0bf7639a1e1b96b34d848ddd0c62f\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage\",\"url\":\"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg\",\"contentUrl\":\"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg\",\"width\":2400,\"height\":1350},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.lbscience.org\/en\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Armageddon? Not today!\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.lbscience.org\/en\/#website\",\"url\":\"https:\/\/www.lbscience.org\/en\/\",\"name\":\"Little, Big Science\",\"description\":\"\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.lbscience.org\/en\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/82a0bf7639a1e1b96b34d848ddd0c62f\",\"name\":\"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/e1c7ef3e4582cb2b11e22f27b9181c9d?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/e1c7ef3e4582cb2b11e22f27b9181c9d?s=96&d=mm&r=g\",\"caption\":\"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2\"},\"description\":\"\u05de\u05e8\u05e6\u05d4 \u05d1\u05de\u05d7\u05dc\u05e7\u05d4 \u05dc\u05d4\u05e0\u05d3\u05e1\u05ea \u05de\u05db\u05d5\u05e0\u05d5\u05ea, \u05d1\u05de\u05db\u05dc\u05dc\u05d4 \u05d4\u05d0\u05e7\u05d3\u05de\u05d9\u05ea \u05dc\u05d4\u05e0\u05d3\u05e1\u05d4 \u05d1\u05e8\u05d0\u05d5\u05d3\u05d4 \u05d1\u05db\u05e8\u05de\u05d9\u05d0\u05dc. \u05d0\u05dc\u05e2\u05d3 \u05d3\u05d5\u05e7\u05d8\u05d5\u05e8 \u05dc\u05de\u05e2\u05e8\u05db\u05d5\u05ea \u05d0\u05d5\u05d8\u05d5\u05e0\u05d5\u05de\u05d9\u05d5\u05ea \u05d5\u05e8\u05d5\u05d1\u05d5\u05d8\u05d9\u05e7\u05d4, \u05d7\u05d5\u05e7\u05e8 \u05d1\u05d9\u05e0\u05d4 \u05de\u05dc\u05d0\u05db\u05d5\u05ea\u05d9\u05ea \u05d5\u05d0\u05d5\u05e4\u05d8\u05d9\u05de\u05d9\u05d6\u05e6\u05d9\u05d4.\",\"sameAs\":[\"https:\/\/x.com\/DenElad\"],\"url\":\"https:\/\/www.lbscience.org\/en\/author\/eladd\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Armageddon? Not today! - Little, Big Science","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/","og_locale":"en_US","og_type":"article","og_title":"Armageddon? Not today! - Little, Big Science","og_description":"Every few months we come across headlines warning us from an asteroid that is getting dangerously close and could wipe us all out [1]. The wording is scary and deliberately alarming (click-bait), yet the panic is unwarranted: although some of us may secretly hope for such drama, the likelihood that an asteroid will exterminate humanity […]","og_url":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/","og_site_name":"Little, Big Science","article_published_time":"2021-08-08T14:02:01+00:00","article_modified_time":"2025-11-26T02:07:42+00:00","og_image":[{"width":2400,"height":1350,"url":"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg","type":"image\/jpeg"}],"author":"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2","twitter_card":"summary_large_image","twitter_creator":"@DenElad","twitter_misc":{"Written by":"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2","Est. reading time":"4 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/","url":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/","name":"Armageddon? Not today! - Little, Big Science","isPartOf":{"@id":"https:\/\/www.lbscience.org\/en\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage"},"image":{"@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage"},"thumbnailUrl":"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg","datePublished":"2021-08-08T14:02:01+00:00","dateModified":"2025-11-26T02:07:42+00:00","author":{"@id":"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/82a0bf7639a1e1b96b34d848ddd0c62f"},"breadcrumb":{"@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#primaryimage","url":"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg","contentUrl":"https:\/\/www.lbscience.org\/en\/wp-content\/uploads\/sites\/3\/2021\/08\/en_meme.jpeg","width":2400,"height":1350},{"@type":"BreadcrumbList","@id":"https:\/\/www.lbscience.org\/en\/2021\/08\/08\/armageddon-not-today\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.lbscience.org\/en\/"},{"@type":"ListItem","position":2,"name":"Armageddon? Not today!"}]},{"@type":"WebSite","@id":"https:\/\/www.lbscience.org\/en\/#website","url":"https:\/\/www.lbscience.org\/en\/","name":"Little, Big Science","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.lbscience.org\/en\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/82a0bf7639a1e1b96b34d848ddd0c62f","name":"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.lbscience.org\/en\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/e1c7ef3e4582cb2b11e22f27b9181c9d?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/e1c7ef3e4582cb2b11e22f27b9181c9d?s=96&d=mm&r=g","caption":"\u05d0\u05dc\u05e2\u05d3 \u05d3\u05e0\u05e0\u05d1\u05e8\u05d2"},"description":"\u05de\u05e8\u05e6\u05d4 \u05d1\u05de\u05d7\u05dc\u05e7\u05d4 \u05dc\u05d4\u05e0\u05d3\u05e1\u05ea \u05de\u05db\u05d5\u05e0\u05d5\u05ea, \u05d1\u05de\u05db\u05dc\u05dc\u05d4 \u05d4\u05d0\u05e7\u05d3\u05de\u05d9\u05ea \u05dc\u05d4\u05e0\u05d3\u05e1\u05d4 \u05d1\u05e8\u05d0\u05d5\u05d3\u05d4 \u05d1\u05db\u05e8\u05de\u05d9\u05d0\u05dc. \u05d0\u05dc\u05e2\u05d3 \u05d3\u05d5\u05e7\u05d8\u05d5\u05e8 \u05dc\u05de\u05e2\u05e8\u05db\u05d5\u05ea \u05d0\u05d5\u05d8\u05d5\u05e0\u05d5\u05de\u05d9\u05d5\u05ea \u05d5\u05e8\u05d5\u05d1\u05d5\u05d8\u05d9\u05e7\u05d4, \u05d7\u05d5\u05e7\u05e8 \u05d1\u05d9\u05e0\u05d4 \u05de\u05dc\u05d0\u05db\u05d5\u05ea\u05d9\u05ea \u05d5\u05d0\u05d5\u05e4\u05d8\u05d9\u05de\u05d9\u05d6\u05e6\u05d9\u05d4.","sameAs":["https:\/\/x.com\/DenElad"],"url":"https:\/\/www.lbscience.org\/en\/author\/eladd\/"}]}},"_links":{"self":[{"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/posts\/293","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/users\/39"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/comments?post=293"}],"version-history":[{"count":9,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/posts\/293\/revisions"}],"predecessor-version":[{"id":1724,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/posts\/293\/revisions\/1724"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/media\/1609"}],"wp:attachment":[{"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/media?parent=293"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/categories?post=293"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lbscience.org\/en\/wp-json\/wp\/v2\/tags?post=293"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}