{"id":42573,"date":"2023-03-23T09:52:45","date_gmt":"2023-03-23T09:52:45","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?post_type=purple_issue&#038;p=42573"},"modified":"2023-03-23T10:13:05","modified_gmt":"2023-03-23T10:13:05","slug":"mercury-returns-to-twilight","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2023\/03\/23\/mercury-returns-to-twilight\/","title":{"rendered":"Mercury returns to twilight"},"content":{"rendered":"\n<figure class=\"no-tts wp-block-image alignfull size-large article-in-image photo\"><img loading=\"lazy\" width=\"1024\" height=\"681\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview-1024x681.jpg\" alt=\"\" class=\"no-tts wp-image-43226\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview-1024x681.jpg 1024w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview-300x200.jpg 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview-768x511.jpg 768w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview-1536x1021.jpg 1536w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/GDFED4_preview.jpg 1600w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption>Small wonder: as the tiniest planet and the closest to the Sun, Mercury isn\u2019t easy to observe but it\u2019s well worth the effort  <\/figcaption><\/figure>\n\n<h2 class=\"has-text-align-center\">Mercury returns to twilight<\/h2>\n\n<p class=\"sans-serif intro\">The inner wanderer graces our evening skies once again this month. <strong>Charlotte <\/strong><strong>Daniels <\/strong>reveals when to look for Mercury, and what you\u2019ll be able to see <\/p>\n\n<p class=\"has-drop-cap article-full-body sans-serif dropcap\">When most beginners start out in planetary astronomy, it\u2019s easy to default to the \u2018holy trinity\u2019 of Jupiter, Saturn and our neighbour Mars. Each boasts unique and relatively easy to observe features, from Saturn\u2019s rings and Jupiter\u2019s bands and Great Red Spot, to Mars\u2019s dusty surface. But why stop there? There are eight planets in our Solar System and many can be appreciated with beginner setups. The \u2018inner planets\u2019, Mercury and Venus, present new and exciting challenges to planetary astronomers. We explored Venus in last month\u2019s issue and now it\u2019s Mercury\u2019s turn for the spotlight. <\/p>\n\n<p class=\"article-full-body sans-serif\">Due to its proximity to the Sun, extra care must be taken to observe Mercury safely, which adds to the challenge. There are particular times that are best to view this elusive, mysterious planet, and this April we can seize the opportunity. Get ready to enjoy one of the Solar System\u2019s unsung heroes. <\/p>\n\n<h4 class=\"sans-serif article-subhead\"><strong>Following Mercury\u2019s path <\/strong><\/h4>\n\n<p class=\"article-full-body sans-serif\">The fastest planet in the Solar System, Mercury is named after the messenger of the Greek gods, renowned for speed. And time is certainly of the essence with this planet. To catch Mercury, we need to understand how its position relative to the Sun affects its visibility. <\/p>\n\n<p class=\"article-full-body sans-serif\">Mercury is 0.4 astronomical units (AU) away from the Sun and orbits at speeds&nbsp;<span>of up to 47km per second, compared to Earth\u2019s relaxed pace of 30km per second. When it reaches its closest point to the Sun, Mercury is at its fastest and it then slows down slightly the further away it gets. As the innermost planet, it also has the shortest year, taking 88 Earth days to circle the Sun.<\/span><\/p>\n\n<ul class=\"no-tts wp-block-purple-slider\" data-autoplay=\"true\" data-speed=\"300\" data-effect=\"fade\"><li class=\"no-tts blocks-gallery-item\"><figure><img src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/2c739586-99c8-44e2-9821-dbce5aa11207.jpg\" alt=\"\" data-id=\"42566\" data-link=\"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2c739586-99c8-44e2-9821-dbce5aa11207\/\"\/><figcaption>Mercury sets alongside Jupiter, right after the Sun in late March<\/figcaption><\/figure><\/li><li class=\"no-tts blocks-gallery-item\"><figure><img src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d005cc8a-8617-4c72-abd0-efb43e80d905.jpg\" alt=\"\" data-id=\"42567\" data-link=\"https:\/\/c01.purpledshub.com\/bbcskyatnight\/d005cc8a-8617-4c72-abd0-efb43e80d905\/\"\/><figcaption>There&#8217;s more time at elongation on 11 April, when a conjunction with Venus and Uranus also lies in store  <\/figcaption><\/figure><\/li><\/ul>\n\n<p class=\"article-full-body sans-serif\">The gravitational influence of the Sun affects Mercury\u2019s orbit in other ways too. Mercury\u2019s journey around the Sun is highly \u2018eccentric\u2019, or egg-shaped: this means the distance between the two can vary from 46,000,000km to 69,000,000km. Moreover, just because Mercury\u2019s years are short, it doesn\u2019t mean its days are. In fact, it rotates so slowly on its axis that it completes one full rotation roughly every 59 Earth days. When we consider the speed that Mercury travels versus its slovenly rotational rate, we realise it doesn\u2019t experience conventional sunrises and sunsets to mark day and night times \u2013 one \u2018solar day\u2019 (a full day\u2013night cycle) on Mercury is 176 Earth days! <\/p>\n\n<p class=\"article-full-body sans-serif\">Another thing that makes Mercury unique is its lack of moons. Anything likely to be bound to the planet is instead attracted by the strong pull of its host star. <\/p>\n\n<h4 class=\"sans-serif article-subhead\"><strong>Elongations and conjunctions <\/strong><\/h4>\n\n<p class=\"article-full-body sans-serif\">Because Mercury is the planet closest to the Sun, it always appears close by and is often swallowed by our home star\u2019s glare. Mercury\u2019s appearances are therefore closely linked with our sunrise and sunsets, making it a morning or evening object, rather than something we can look for during later hours. <\/p>\n\n<p class=\"article-full-body sans-serif\">The best time to view Mercury is during greatest elongation, which next occurs on <strong>11 April<\/strong>. This is when Mercury is farthest from the Sun, so it is placed far either to the east or west side of it (known as eastern and western elongations, respectively). What we\u2019ll have on 11 April is a greatest eastern elongation event. This places it a little further from the Sun\u2019s glare and at its highest altitude, helping us to view it. The angular separation due to elongation can vary from roughly 20\u00b0 to 28\u00b0, the equivalent of one handspan to three clenched fists next to each other, held at arm\u2019s length. When positioned at the eastern side of the Sun, Mercury appears in our evening skies; when at the western side it appears in early morning skies. When it makes its evening appearances, the planet is seen above the western horizon shortly after sunset in twilight (as it will be around 2\u201315 April), and as a morning planet it appears in the east shortly before sunrise (as it will be around 27\u201331 May). A very clear eastern horizon will be needed. <\/p>\n\n<p class=\"article-full-body sans-serif\">These elongation events mark Mercury\u2019s best and safest observing periods. Because Mercury is closest to the Sun, elongations are regular and happen every <span>3\u20134 months. It\u2019s at this point that the planet will <\/span><span>appear <\/span><span>highest above the horizon, placing it at the <\/span><span>best position to observe as it will be clear of light <\/span><span>pollution and least affected by atmospheric seeing. <\/span><span>Mercury reaches this point on 11 April, making this <\/span><span>a great time to start looking for it. Even so, it never strays far from the Sun, with this elongation only reaching a maximum angular separation of 19.5\u00b0.<\/span><\/p>\n\n<figure class=\"no-tts wp-block-image article-in-image bild\"><img loading=\"lazy\" width=\"1225\" height=\"1318\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/b619faf4-a95e-4f75-b2be-58f221fdafbc.jpg\" alt=\"\" class=\"no-tts wp-image-42568\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/b619faf4-a95e-4f75-b2be-58f221fdafbc.jpg 1225w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/b619faf4-a95e-4f75-b2be-58f221fdafbc-279x300.jpg 279w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/b619faf4-a95e-4f75-b2be-58f221fdafbc-952x1024.jpg 952w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/b619faf4-a95e-4f75-b2be-58f221fdafbc-768x826.jpg 768w\" sizes=\"(max-width: 1225px) 100vw, 1225px\" \/><figcaption>The best time to catch the planet is at eastern or western elongation, when its orbit brings it far enough from the Sun\u2019s glare <\/figcaption><\/figure>\n\n<p class=\"article-full-body sans-serif\">Inferior and superior conjunctions are specific to the inner planets, and mark times when we can\u2019t view Mercury. Inferior conjunctions refer to times when Mercury or Venus pass directly between Earth and the Sun, positioning them in front of the Sun at sunrise and sunset, so they are lost in its glare. Superior conjunctions refer to times when these two planets are positioned on the opposite side of the Sun to Earth, again making them unviewable. Mercury next reaches inferior conjunction on <strong>1 May<\/strong> and superior conjunction on <strong>1 July<\/strong>. <\/p>\n\n<figure class=\"no-tts wp-block-image article-in-image photo\"><img loading=\"lazy\" width=\"2048\" height=\"878\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da.jpg\" alt=\"\" class=\"no-tts wp-image-42569\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da.jpg 2048w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da-300x129.jpg 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da-1024x439.jpg 1024w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da-768x329.jpg 768w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/1658309d-0d07-4ac0-bda3-e2ca646dd9da-1536x659.jpg 1536w\" sizes=\"(max-width: 2048px) 100vw, 2048px\" \/><figcaption>Just like the Moon, Mercury exhibits a range of phases as viewed from Earth throughout the year SIMULATION <\/figcaption><\/figure>\n\n<p class=\"article-full-body sans-serif\">So what can we observe when the time is right <span>for Mercury? Despite its challenges, the planet can be appreciated with and without a telescope. If viewed with the naked eye, it tends to appear as a bright point object, similar in appearance to a star, with its magnitude varying from as bright as mag. \u20132.8 to a dim mag. +7, when it is only visible through binoculars or a telescope. If close to the horizon, atmospheric turbulence might make it appear to \u2018twinkle\u2019 like a star. However, if you take some time to study it unaided you will detect a subtle, rosy, golden tinge that singles it out from the starry background. Mercury\u2019s apparent diameter, depending on its distance from Earth, can range from 4.5 arcseconds at apogee to 12.9 arcseconds at perigee. A pair of low-powered binoculars will help you locate the planet, particularly at times when it is dimmer.<\/span><\/p>\n\n<p class=\"article-full-body sans-serif\">Because Mercury is often viewed against brighter skies, a telescope will help you locate it. Again, you\u2019ll want clear western or eastern horizons (depending on when you\u2019re viewing). With a 3-inch scope you\u2019ll <span>start to appreciate Mercury\u2019s phases. Although the planet is unobservable at its full phase during superior conjunction and at its new phase at inferior conjunction, even in the short windows of opportunity in between you will notice changes in its phases.<\/span><\/p>\n\n<ul class=\"no-tts wp-block-purple-slider\" data-autoplay=\"true\" data-speed=\"300\" data-effect=\"fade\"><li class=\"no-tts blocks-gallery-item\"><figure><img src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/655eb13b-ffe4-4009-a55e-162b9c6ea4a8.jpg\" alt=\"\" data-id=\"42570\" data-link=\"https:\/\/c01.purpledshub.com\/bbcskyatnight\/655eb13b-ffe4-4009-a55e-162b9c6ea4a8\/\"\/><figcaption>From afar Mercury is a tiny but distinct dot in the sky, but&#8230;<\/figcaption><\/figure><\/li><li class=\"no-tts blocks-gallery-item\"><figure><img src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/5d206101-5a4a-4332-86d5-2e6b4dfef509.jpg\" alt=\"\" data-id=\"42571\" data-link=\"https:\/\/c01.purpledshub.com\/bbcskyatnight\/5d206101-5a4a-4332-86d5-2e6b4dfef509\/\"\/><figcaption>&#8230;even with a modest telescope you can see much more <\/figcaption><\/figure><\/li><\/ul>\n\n<p class=\"article-full-body sans-serif\">While we won\u2019t see craters, on nights of exceptional seeing and minimal turbulence, we may discern some surface details with larger-aperture telescopes. With all planetary astronomy, seeing conditions will greatly affect observations. Therefore, providing it\u2019s safe to do so, try to catch the planet at its highest possible altitude, at a minimum of one hour outside of sunrise or sunset times. <\/p>\n\n<p class=\"article-full-body sans-serif\">Because it is so closely bound to our Sun, it is imperative when viewing Mercury to avoid the risk of viewing the Sun directly. Never try to find Mercury in broad daylight or during conjunctions; aim instead for elongation events. Ascertain the sunrise or sunset time on the day of observation and use a sky guide to establish the angular separation of Mercury from the Sun. Ensure that the full disc of the Sun is behind the horizon at the time of viewing. <\/p>\n\n<h4 class=\"sans-serif article-subhead\"><strong>When to observe Mercury <\/strong><\/h4>\n\n<p class=\"article-full-body sans-serif\">You can catch Mercury in the evening sky and close to Jupiter on <strong>27 March<\/strong>, less than half a degree apart from Jupiter\u2019s southeastern limb. It will be a bright mag. \u20131.3, comparable to Jupiter at mag. \u20131.59, and great to view whether with the naked eye or through a telescope. Be quick, however, as it will set an hour after sunset, which is at around 19:25 BST (18:25 UT). A clear western horizon is needed. <\/p>\n\n<p class=\"article-full-body sans-serif\">April is a great time to view Mercury as it meets all the criteria required to enjoy this planet: it\u2019s at its furthest distance from the Sun and relatively high above the horizon at sunset, meaning we can catch it once the Sun is safely out of the way. Mercury is best at the start and middle of the month, when its magnitude will vary from mag. \u20131.0 to mag. +1.2 over the first two weeks \u2013 very bright to the naked eye, providing you have good horizons. It will be at greatest elongation east on <strong>11 April<\/strong>, reaching 16\u00b0 altitude and positioned close to both Uranus and Venus at sunset. It will set two hours later, giving us plenty of time to see it. The remainder of April will see Mercury dim as its peak altitude gets lower. By the month\u2019s end, it is expected to be mag. +4.3 and only 6\u00b0 above the western horizon at sunset. <\/p>\n\n<p class=\"article-full-body sans-serif\">From the end of March to the end of April, those with telescopes can observe Mercury wane from an almost full 91%-lit disc on <strong>28 March<\/strong> to 7%-lit on <strong>24 April<\/strong>. Naturally, as the disc becomes smaller the planet dims and therefore becomes harder to make out, in addition to sinking further towards the horizon. <\/p>\n\n<p class=\"article-full-body sans-serif\">Whether you\u2019re looking with the naked eye or using magnification, if you\u2019ve never taken the time to appreciate Mercury before, now\u2019s the perfect time. <\/p>\n\n<p><\/p>\n\n<hr class=\"no-tts wp-block-separator is-style-wide\"\/>\n\n<h4 class=\"has-text-align-center\">What\u2019s next for Mercury?<\/h4>\n\n<p class=\"has-text-align-center sans-serif intro\">Keep an eye out for more chances to see the planet in the months ahead <\/p>\n\n<p class=\"article-full-body sans-serif\">After April, Mercury goes quiet for a little while. On <strong>1 May<\/strong> there\u2019s an inferior conjunction, where it\u2019s positioned directly between the Sun and Earth. This position in the morning sky will make it almost impossible to observe as not only is it hidden in the Sun\u2019s glare, but it appears as a thin crescent so is hard to pick out even with a telescope. On <strong>29 May<\/strong> it will reach greatest western elongation. On <strong>16 June<\/strong>, it will appear close to a 3%-illuminated Moon. July and August will prove disappointing for Mercury, as at best it will make brief appearances very low on the horizon and in light evening skies. <\/p>\n\n<p class=\"article-full-body sans-serif\">September will see Mercury\u2019s greatest western elongation on <strong>22 September<\/strong>, meaning the planet will make another welcome appearance, rising 100 minutes before sunrise and climbing to 10\u00b0 above the eastern horizon. Make the most of the planet looking bright in early morning skies during the <strong>first week of October <\/strong>before it lurks low on the horizon after sunset for much of November. By <strong>31 December<\/strong>, Mercury will make a final brief appearance in the morning, just above the southeast horizon before sunrise. <\/p>\n\n<figure class=\"no-tts wp-block-image article-in-image bild is-style-default\"><img loading=\"lazy\" width=\"1402\" height=\"1059\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/61fe7901-48ee-4ad7-b6a1-7b77305cdab4.jpg\" alt=\"\" class=\"no-tts wp-image-42579\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/61fe7901-48ee-4ad7-b6a1-7b77305cdab4.jpg 1402w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/61fe7901-48ee-4ad7-b6a1-7b77305cdab4-300x227.jpg 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/61fe7901-48ee-4ad7-b6a1-7b77305cdab4-1024x773.jpg 1024w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/61fe7901-48ee-4ad7-b6a1-7b77305cdab4-768x580.jpg 768w\" sizes=\"(max-width: 1402px) 100vw, 1402px\" \/><figcaption>One of the best sights will be Mercury\u2019s pairing with a sliver of a Moon early on 16 June <\/figcaption><\/figure>\n\n<section class=\"wp-block-uagb-section uagb-section__wrap uagb-section__background-color uagb-block-95420aec-77c5-436d-abe0-5afda4f68f20\"><div class=\"uagb-section__overlay\"><\/div><div class=\"uagb-section__inner-wrap\">\n<h4><span class=\"has-inline-color has-ccp-white-color\">Unravelling Mercury\u2019s mysteries<\/span><\/h4>\n\n\n\n<p class=\"sans-serif intro\"><span class=\"has-inline-color has-ccp-white-color\"><strong>What do we know about the innermost planet, and how has humanity explored it? <\/strong><\/span><\/p>\n\n\n\n<figure class=\"no-tts wp-block-image article-in-image photo is-style-default\"><img loading=\"lazy\" width=\"1984\" height=\"1982\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe.jpg\" alt=\"\" class=\"no-tts wp-image-42575\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe.jpg 1984w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe-300x300.jpg 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe-1024x1024.jpg 1024w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe-150x150.jpg 150w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe-768x767.jpg 768w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/d6f8f303-e0a8-4825-86d7-7198cb3c49fe-1536x1534.jpg 1536w\" sizes=\"(max-width: 1984px) 100vw, 1984px\" \/><figcaption><span class=\"no-tts has-inline-color has-ccp-white-color\">Two spacecraft have now visited Mercury: Mariner 10 in 1973 (top) and Messenger in 2004 (bottom)<\/span><\/figcaption><\/figure>\n\n\n\n<p class=\"article-full-body sans-serif has-ccp-white-color has-text-color\">Mercury is the smallest planet, barely larger than our own Moon at a mere 2,440km in diameter. As it\u2019s also the closest to the Sun, you\u2019d be forgiven for thinking it\u2019s the hottest planet in the system, but that\u2019s not the case due to a thin \u2018exosphere\u2019 of oxygen, hydrogen, sodium, helium and potassium. Lack of heat retention means its surface temperature varies from almost 450\u00b0C in the day to \u2013180\u00b0C at night. Despite being further away, Venus reaches temperatures up to 470\u00b0C thanks to its thick atmosphere. <\/p>\n\n\n\n<p class=\"article-full-body sans-serif has-ccp-white-color has-text-color\">Mercury is a \u2018terrestrial\u2019 or rocky planet, displaying a cratered surface that resembles Earth\u2019s Moon. Underneath lies a large metallic core, mantle and crust. Thanks to a minor axial tilt (2\u00b0), Mercury doesn\u2019t experience seasons. <\/p>\n\n\n\n<p class=\"article-full-body sans-serif has-ccp-white-color has-text-color\">To date, two NASA missions have visited Mercury. Mariner 10 launched in 1973 and flew past the next year, observing the cratered surface. Messenger followed in 2004 and was the first to orbit, in 2011. Discoveries included ice at the poles and the presence of relatively new fault \u2018cliffs\u2019&nbsp;<span>on the surface, hinting at tectonic activity. These fault lines suggest Mercury is contracting and \u2018shrinking\u2019 as the molten interior cools, warping the surface. Over its lifetime, Mercury is estimated to have shrunk by almost 16km (10 miles).<\/span><\/p>\n\n\n\n<p class=\"article-full-body sans-serif has-ccp-white-color has-text-color\">The European Space Agency now has BepiColombo winging its way over, expecting to arrive in 2025. It will take a closer look at the magnetic field, core and polar ice, to learn more about Mercury\u2019s early life. <\/p>\n\n\n\n<figure class=\"no-tts wp-block-image article-in-image photo is-style-default\"><img loading=\"lazy\" width=\"2048\" height=\"950\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1.jpg\" alt=\"\" class=\"no-tts wp-image-42576\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1.jpg 2048w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1-300x139.jpg 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1-1024x475.jpg 1024w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1-768x356.jpg 768w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/44530dbf-0152-42f2-9899-3c0826badeb1-1536x713.jpg 1536w\" sizes=\"(max-width: 2048px) 100vw, 2048px\" \/><figcaption><span class=\"no-tts has-inline-color has-ccp-white-color\">Rays, ridges, craters and basins were imaged by NASA\u2019s Mariner 10 (left) in the 1970s before the Messenger spacecraft in 2011\u201315 took tens of thousands of images, revealing far more detailed pictures (right) of fault lines, double-ringed craters and other tectonic activity <\/span><\/figcaption><\/figure>\n<\/div><\/section>\n\n<p><\/p>\n\n<p class=\"article-full-body sans-serif\"><strong>For more details about observing Mercury this month, <a href=\"navto:\/\/index\/33\">take a look at the planets section in our Sky Guide<\/a>.<\/strong><\/p>\n\n<p><\/p>\n\n<hr class=\"no-tts wp-block-separator is-style-wide\"\/>\n\n<div class=\"no-tts wp-block-image article-in-image photo\"><figure class=\"no-tts alignleft size-large is-resized\"><img loading=\"lazy\" src=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/Layer-0-3.png\" alt=\"\" class=\"no-tts wp-image-43242\" width=\"49\" height=\"49\" srcset=\"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/Layer-0-3.png 315w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/Layer-0-3-300x300.png 300w, https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2023\/03\/Layer-0-3-150x150.png 150w\" sizes=\"(max-width: 49px) 100vw, 49px\" \/><\/figure><\/div>\n\n<p>Charlotte Daniels is an experienced practical astronomer and astrophotographer<\/p>\n\n<p><\/p>\n\n<p class=\"footer\">PHOTOS: WALTER MYERS\/SCIENCE PHOTO LIBRARY, ILLUSTRATION BY PAUL WOOTTON, PETE LAWRENCE, NASA<\/p>\n","protected":false},"excerpt":{"rendered":"<p>When to look for the innermost planet and what you\u2019ll be able to see 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