[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-115589-en":3,"doc-seo-115589-105":31,"detail-sidebar-cat-0-en-105":92},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":21,"is_downloadable":21,"audit_status":21,"page_count":22,"language":23,"language_code":24,"site_id":25,"html_lang":24,"table_of_contents":26,"faqs":27,"seo_title":28,"seo_description":14,"update_tm":29,"read_time":30},115589,137451207643,"Noah","https://ap-avatar.wpscdn.com/davatar_3d24733baf745e90a7e4bdd5f77d97b2",8,"Research & Report","Mercury - William Sheehan","Mercury explores the planet through science, astronomy observation, and space-mission evidence, tracing how understanding shifted from early sightings and daylight mapping to modern radio and spacecraft discoveries. It explains why Mercury is hard to see, details key findings such as the 58.65-day rotation period and its spin–orbit coupling, and discusses unexpected ice in permanently shadowed polar craters. The narrative also addresses remaining mysteries, including the planet’s unusually iron-rich core.","MERCURY  \n[OceanofPDF.com](OceanofPDF.com)  \nKOSMOS  \nA series exploring our expanding knowledge of the cosmos through science and technology and investigating historical, contemporary and future developments as well as providing guidance for all those interested in astronomy.  \nSeries Editor: Peter Morris  \nAlready published:  \nJupiter William Sheehan and Thomas Hockey Mercury William Sheehan  \nThe Moon Bill Leatherbarrow  \nThe Sun Leon Golub and Jay M. Pasachoff  \n[OceanofPDF.com](OceanofPDF.com)  \nMercury  \nWilliam Sheehan  \nREAKTION BOOKS  \n[OceanofPDF.com](OceanofPDF.com)  \nTo Clark Chapman and Dale Cruikshank, who largely inspired my love of Mercury  \nPublished by Reaktion Books Ltd Unit 32, Waterside  \n44–48 Wharf Road London N1 7UX, UK  \n[www.reaktionbooks.co.uk](www.reaktionbooks.co.uk)  \nFirst published 2018  \nCopyright © William Sheehan 2018 All rights reserved  \nNo part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers  \nPage references in the Photo Acknowledgements and Index match the printed edition of this book.  \nPrinted and bound in China  \nA catalogue record for this book is available from the British Library eISBN: 9781789140224  \n[OceanofPDF.com](OceanofPDF.com)  \nCONTENTS  \nPREFACE  \n1 THE SCINTILLATING ONE  \n2 MOTIONS OF MERCURY  \n3 THROUGH THE TELESCOPE  \n4 ROTATION  \n5 MERCURY UP CLOSE  \n6 VULCAN  \nAPPENDIX I: GLOSSARY  \nAPPENDIX II: BASIC DATA  \nAPPENDIX III: CRATERS  \nREFERENCES  \nFURTHER READING  \nACKNOWLEDGEMENTS  \nPHOTO ACKNOWLEDGEMENTS  \nINDEX  \n[OceanofPDF.com](OceanofPDF.com)  \nCaloris basin. A colour-enhanced composite overlain on a monochrome mosaic of MESSENGER images. The basin has been flooded by lavas that are colour-coded orange in this mosaic. Postflooding craters have excavated material from below the surface, which – in the case of larger craters – has exposed low-reflectance material (blue). This likely represents the original basin floor material. Analysis of these craters yields an estimate of the thickness of the volcanic layer: 2.5–3.5 km.  \nPREFACE  \nMercuryl ranks among the five planets known in  \nong had a reputation for being difficult to see  \nancient times, and has – though there is no  \ntruth to the legend that even Copernicus could never distinguish it. In fact, it can become quite as bright as Jupiter, and stands out readily when at its greatest elongations from the Sun. From northern latitudes, the best opportunities for seeing Mercury in the evening sky always occur in the spring, and for seeing it in the morning sky in the autumn.  \nTo the naked eye, Mercury appears to twinkle, owing both to its small size (its diameter is only half again larger than the Moon’s) and to its being seen through the full thickness of the Earth’s roiling atmosphere. Without taking special precautions, a telescope will usually show little more than the moon-like phases characteristic of the inferior planets – those travelling closer to the Sun than the Earth. Historically, a breakthrough in the study of Mercury occurred in the 1880s, when the great Italian astronomer Giovanni Schiaparelli showed the feasibility of observing it in broad daylight. He produced a map of Mercury, and also believed that he had worked out the rotation period, which he put equal to the period of revolution around the Sun – 88 days.  \nThough other observers – most notably the skilful Graeco-French astronomer Eugène Michel Antoniadi – followed in his footsteps, in fact much of what we thought we knew about Mercury before the 1960s, including the rotation period, was wrong. This says nothing about the skill or dedication of the observers who tried to study it with telescopes from  \nEarth. They made mistakes, but they were hardly blameworthy; rather, they stand as testimony to the difficulty of observing, under challenging conditions, the surface of ","cbCairNcm2fcDXdC","https://ap.wps.com/l/cbCairNcm2fcDXdC","pdf",21854844,2,1,183,"English","en",105,"# Preface\n## The Scintillating One\n## Motions of Mercury\n## Through the Telescope\n## Rotation\n## Mercury Up Close\n## Vulcan\n## Appendix I: Glossary\n## Appendix II: Basic Data\n## Appendix III: Craters\n## References\n## Further Reading\n## Acknowledgements\n## Photo Acknowledgements\n## Index","[{\"question\":\"Why is Mercury difficult to observe from Earth?\",\"answer\":\"Mercury is small and seen through the full thickness of Earth’s roiling atmosphere, so telescopes often show little more than its moon-like phases. Its visibility is also limited to specific times of year and sky positions.\"},{\"question\":\"What was the major breakthrough in Mercury research in the 1880s?\",\"answer\":\"Giovanni Schiaparelli demonstrated that Mercury could be observed in broad daylight, produced a map, and proposed a rotation period equal to the revolution period, though later work showed this was incorrect.\"},{\"question\":\"What changed understanding of Mercury in the 1960s and what did it reveal?\",\"answer\":\"Radio telescopes enabled a modern understanding, including the discovery of a 58.65-day rotation period. This period is exactly two-thirds of Mercury’s orbital period and indicates a unique spin–orbit coupling, plus evidence of bright water-ice patches in permanently shadowed polar craters.\"}]","Mercury - William Sheehan | PDF",1785474909,461,{"code":4,"msg":32,"data":33},"ok",{"site_id":25,"language":24,"slug":34,"title":13,"keywords":35,"description":14,"schema_data":36,"social_meta":87,"head_meta":89,"extra_data":91,"updated_unix":29},"mercury-william-sheehan","",{"@graph":37,"@context":86},[38,54,69],{"@type":39,"itemListElement":40},"BreadcrumbList",[41,45,48,51],{"item":42,"name":43,"@type":44,"position":21},"https://docshare.wps.com","Home","ListItem",{"item":46,"name":47,"@type":44,"position":20},"https://docshare.wps.com/document/","Document",{"item":49,"name":12,"@type":44,"position":50},"https://docshare.wps.com/document/research-report/",3,{"item":52,"name":13,"@type":44,"position":53},"https://docshare.wps.com/document/mercury-william-sheehan/115589/",4,{"url":52,"name":13,"@type":55,"author":56,"headline":13,"publisher":58,"fileFormat":61,"inLanguage":24,"description":14,"dateModified":62,"datePublished":63,"encodingFormat":61,"isAccessibleForFree":64,"interactionStatistic":65},"DigitalDocument",{"name":9,"@type":57},"Person",{"url":42,"name":59,"@type":60},"DocShare","Organization","application/pdf","2026-08-15","2026-07-31",true,{"@type":66,"interactionType":67,"userInteractionCount":20},"InteractionCounter",{"@type":68},"ViewAction",{"@type":70,"mainEntity":71},"FAQPage",[72,78,82],{"name":73,"@type":74,"acceptedAnswer":75},"Why is Mercury difficult to observe from Earth?","Question",{"text":76,"@type":77},"Mercury is small and seen through the full thickness of Earth’s roiling atmosphere, so telescopes often show little more than its moon-like phases. Its visibility is also limited to specific times of year and sky positions.","Answer",{"name":79,"@type":74,"acceptedAnswer":80},"What was the major breakthrough in Mercury research in the 1880s?",{"text":81,"@type":77},"Giovanni Schiaparelli demonstrated that Mercury could be observed in broad daylight, produced a map, and proposed a rotation period equal to the revolution period, though later work showed this was incorrect.",{"name":83,"@type":74,"acceptedAnswer":84},"What changed understanding of Mercury in the 1960s and what did it reveal?",{"text":85,"@type":77},"Radio telescopes enabled a modern understanding, including the discovery of a 58.65-day rotation period. This period is exactly two-thirds of Mercury’s orbital period and indicates a unique spin–orbit coupling, plus evidence of bright water-ice patches in permanently shadowed polar craters.","https://schema.org",{"og:url":52,"og:type":88,"og:title":13,"og:site_name":59,"og:description":14},"article",{"robots":90,"canonical":52},"index,follow",{"doc_id":7,"site_id":25},{"code":4,"msg":5,"data":93},[94,98,102,106,111,116,121,124,129,132,136],{"id":21,"doc_module":4,"doc_module_name":47,"category_name":95,"show_sort_weight":96,"slug":97},"Story & Novel",90,"story-novel",{"id":20,"doc_module":4,"doc_module_name":47,"category_name":99,"show_sort_weight":100,"slug":101},"Literature",80,"literature",{"id":53,"doc_module":4,"doc_module_name":47,"category_name":103,"show_sort_weight":104,"slug":105},"Exam",70,"exam",{"id":107,"doc_module":4,"doc_module_name":47,"category_name":108,"show_sort_weight":109,"slug":110},5,"Comic",60,"comic",{"id":112,"doc_module":4,"doc_module_name":47,"category_name":113,"show_sort_weight":114,"slug":115},6,"Technology",50,"technology",{"id":117,"doc_module":4,"doc_module_name":47,"category_name":118,"show_sort_weight":119,"slug":120},7,"Healthcare",40,"healthcare",{"id":11,"doc_module":4,"doc_module_name":47,"category_name":12,"show_sort_weight":122,"slug":123},30,"research-report",{"id":125,"doc_module":4,"doc_module_name":47,"category_name":126,"show_sort_weight":127,"slug":128},9,"Religion & Spirituality",20,"religion-spirituality",{"id":127,"doc_module":4,"doc_module_name":47,"category_name":130,"show_sort_weight":127,"slug":131},"World Cup","world-cup",{"id":133,"doc_module":4,"doc_module_name":47,"category_name":134,"show_sort_weight":133,"slug":135},10,"Lifestyle","lifestyle",{"id":137,"doc_module":4,"doc_module_name":47,"category_name":138,"show_sort_weight":107,"slug":139},19,"General","general"]