{"id":21434,"date":"2026-11-05T09:08:43","date_gmt":"2026-11-05T08:08:43","guid":{"rendered":"https:\/\/deep-space-astronomy.ch\/?p=21434"},"modified":"2026-11-05T09:08:43","modified_gmt":"2026-11-05T08:08:43","slug":"mercure-elongation-ouest-20-novembre-2026-observer-planete-fugitive-aube","status":"publish","type":"post","link":"https:\/\/deep-space-astronomy.ch\/en\/mercure-elongation-ouest-20-novembre-2026-observer-planete-fugitive-aube\/","title":{"rendered":"Mercury Before Dawn: The Fleeting Planet to Watch on November 20"},"content":{"rendered":"<div class=\"product\"><div class=\"product\"><p>Mercury reaches its greatest western elongation from the Sun on November 20, 2026. This is its best viewing window in the fall mornings. Low in the east before dawn, the fleeting planet can be seen with the naked eye if the horizon is clear. But behind this bright spot lies a surprising planet: some astrophotographers have managed to capture its sodium tail, which stretches 2.5 million kilometers long.<\/p>\n<h2>All the info at a glance<\/h2>\n<ul>\n<li>Date: Maximum western elongation on November 20, 2026<\/li>\n<li>Angular separation: approximately 19\u00b0 west of the Sun<\/li>\n<li>Magnitude: approximately -0.4 (bright)<\/li>\n<li>Visibility: 30\u201345 minutes before sunrise, low in the east-southeast<\/li>\n<li>Optimal window: November 20\u201321, 2026<\/li>\n<li>Constellation: Libra, then Virgo<\/li>\n<li>Phase: approximately 60\u201370 % (gibbous)<\/li>\n<li>Apparent diameter: approximately 5\u20136 arcseconds<\/li>\n<li>Visible from: all of Switzerland and all of France<\/li>\n<li>Equipment: Viewable with the naked eye; 10\u00d750 binoculars recommended; 70 mm+ telescope for this phase<\/li>\n<li>Difficulty: moderate (clear view required)<\/li>\n<\/ul>\n<figure><img decoding=\"async\" src=\"https:\/\/deep-space-astronomy.ch\/wp-content\/uploads\/2026\/11\/mercury-messenger.jpg\" alt=\"Mercure vue par la sonde MESSENGER de la NASA\" \/><figcaption>Mercury as seen by the MESSENGER spacecraft. Credit: NASA \/ JHU APL \/ Carnegie Institution of Washington. Public domain, via Wikimedia Commons.<\/figcaption><\/figure>\n<h2>When and Where to Watch: A Practical Guide<\/h2>\n<p>Mercury is the hardest planet to see in the solar system. Not because it is faint, but because it never strays very far from the Sun. On November 20, 2026, it reaches its greatest western elongation: about 19\u00b0 west of the Sun. This is a morning elongation: Mercury rises before the Sun.<\/p>\n<p>The viewing window is narrow. 30 to 45 minutes before sunrise, look low in the east-southeast. The sky is beginning to brighten, but Mercury is still visible. Too early: Mercury is too low. Too late: the Sun drowns it out with its brilliance.<\/p>\n<p>From Switzerland (latitude 46\u201347\u00b0 N), Mercury reaches an altitude of about 10\u201315\u00b0 above the horizon at the optimal viewing time. This is better than the eastern elongation in October (8\u201310\u00b0), because in November the ecliptic forms a wider angle with the eastern horizon. But it\u2019s still low: a tree, a building, or a hill to the east-southeast is enough to block it from view. Choose a clear horizon.<\/p>\n<h2>How to Spot Mercury<\/h2>\n<p>Look for a bright, pinkish-white point of light that shines brighter than the surrounding stars. At magnitude -0.4, Mercury is brighter than most stars visible to the naked eye. But it is low on the horizon, where atmospheric refraction and haze make it harder to see.<\/p>\n<p>Through 10\u00d750 binoculars: Mercury appears as a bright point, not as a disk. This is enough to locate it and confirm its presence. Through a 70 mm+ telescope at 50x\u2013100x magnification: a small disk appears, showing a phase (gibbous, approximately 60\u201370 %). This is one of the rare cases where a planet displays a visible phase through a telescope.<\/p>\n<p>Use an app (Stellarium, SkySafari, Star Walk) to locate Mercury before looking for it with the naked eye. Point toward the east-southeast, and the app will tell you exactly where to look.<\/p>\n<h2>Mercury's Sodium Tail: When Astrophotography Gets Wild<\/h2>\n<p>Mercury looks like a comet. This was revealed by Dr. Sebastian Voltmer, a German astrophotographer based in Spicheren, France, in a series of photos that went viral on social media and was selected as NASA\u2019s Image of the Day (APOD, May 3, 2022).<\/p>\n<p>The solar wind and micrometeorites strip sodium atoms from Mercury\u2019s surface. This sodium, illuminated by the Sun, forms a yellow-orange tail of sodium gas about 2.5 million kilometers long. It\u2019s like a comet\u2019s tail, but emanating from a planet. The phenomenon was predicted in the 1980s and observed for the first time two decades later.<\/p>\n<p>Voltmer captured this tail from the Roque de los Muchachos Observatory on La Palma, using a 135-mm lens and a 589-nm filter tuned to the sodium emission line. Without this filter, the tail is invisible to the naked eye. With it, the tail appears in its full length. Voltmer also photographed Mercury\u2019s surface (craters) using planetary imaging with a C11 EdgeHD telescope and documented the rapid evolution of the sodium tail over the course of a week.<\/p>\n<p>His Ph.D. in scientific photography (University of Applied Arts Vienna) and his work at the intersection of media theory and astronomy have enabled him to take this type of photography to a level rarely achieved. His images are protected by copyright: we do not reproduce them here, but you can view them on his website (voltmer.photo) and his X account (@SeVoSpace).<\/p>\n<p>For those who\u2019d like to give it a try: you\u2019ll need a 589-nm filter (sodium filter), a 135-mm lens or a telescope, a sensitive CCD or CMOS camera, and a very dark sky. The tail is most visible when Mercury is near the Pleiades, which isn\u2019t the case in November 2026. However, the elongation on November 20 remains the best time to observe the planet itself.<\/p>\n<h2>Why this stretch is better than the one in October<\/h2>\n<p>The elongation on October 12, 2026 (already covered on the blog) was an evening elongation: Mercury was visible after sunset, low in the west. In the fall, the ecliptic forms a shallow angle with the western horizon in the Northern Hemisphere. Mercury remained very low (8\u201310\u00b0).<\/p>\n<p>The western elongation on November 20 is a morning elongation. In the fall, the ecliptic is more open toward the eastern horizon. Mercury rises higher before dawn: 10\u201315\u00b0 in altitude, sometimes higher depending on the latitude. This makes for more comfortable observing, even if it means getting up early.<\/p>\n<h2>Recommended Equipment<\/h2>\n<ul>\n<li><strong>With the naked eye<\/strong> : enough to spot Mercury in a clear sky with an unobstructed horizon.<\/li>\n<li><strong>10\u00d750 Binoculars<\/strong> : to locate and confirm. The best value for the money.<\/li>\n<li><strong>70\u2013100 mm Telescope<\/strong> : to observe the phase of Mercury (gibbous). A compact Maksutov (MK105 Pro for CHF 299) or a planetary telescope is ideal.<\/li>\n<li><strong>150 mm+ Telescope<\/strong> : to analyze the phase in greater detail. Caution: Never point the telescope at the Sun.<\/li>\n<\/ul>\n<p>A planetarium app (Stellarium, SkySafari) is essential for locating Mercury before sunrise.<\/p>\n<h2>Why shop at Deep Space Astronomy?<\/h2>\n<p>We're not just a retailer. We test, advise, and provide support.<\/p>\n<ul>\n<li><strong>Personalized Advice<\/strong> : We can advise you on choosing the right instrument for observing the planets based on your local sky conditions and your budget. By phone, WhatsApp, or by appointment in Nyon.<\/li>\n<li><strong>After-Sales Support<\/strong> : Do you have a question about the location, equipment, or processing of your images? We're here to help.<\/li>\n<li><strong>14-Day Return Policy<\/strong> : Not satisfied? Return the product within 14 days.<\/li>\n<li><strong>Secure payment<\/strong> : Twint, credit card, invoice, Apple Pay, Bitcoin. Pay in 3 or 4 installments with no fees.<\/li>\n<li><strong>Free shipping in Switzerland<\/strong> Starting at CHF 200. Free pickup in Nyon.<\/li>\n<\/ul>\n<p>Discover our <a href=\"https:\/\/deep-space-astronomy.ch\/en\/product-category\/visuel\/\">telescopes for observation<\/a> and our <a href=\"https:\/\/deep-space-astronomy.ch\/en\/product-category\/montures\/\">frames<\/a> for planetary observation.<\/p>\n<h2>Sources<\/h2>\n<p>This article is based on the ephemeris data from EarthSky (Mercury\u2019s greatest western elongation, November 2026), In-The-Sky.org (Mercury elongation, November 20, 2026), and on Dr. Sebastian Voltmer\u2019s work on Mercury\u2019s sodium tail (APOD, May 3, 2022; voltmer.photo; @SeVoSpace). The image of Mercury is from the MESSENGER spacecraft (NASA \/ JHU APL \/ Carnegie Institution of Washington), in the public domain, via Wikimedia Commons.<\/p>\n<p>CBurkhalter<\/p>\n<\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Mercure \u00e0 sa plus grande \u00e9longation ouest le 20 novembre 2026. Guide d&rsquo;observation, queue de sodium photographi\u00e9e par le Dr Sebastian Voltmer, et conseil mat\u00e9riel.<\/p>","protected":false},"author":187,"featured_media":21433,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[827],"tags":[],"class_list":["post-21434","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites"],"_links":{"self":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/posts\/21434","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/users\/187"}],"replies":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/comments?post=21434"}],"version-history":[{"count":1,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/posts\/21434\/revisions"}],"predecessor-version":[{"id":21435,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/posts\/21434\/revisions\/21435"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media\/21433"}],"wp:attachment":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media?parent=21434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/categories?post=21434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/tags?post=21434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}