{"id":104963,"date":"2025-03-10T06:00:00","date_gmt":"2025-03-10T05:00:00","guid":{"rendered":"https:\/\/www.futuribles.com\/under-alien-skies\/"},"modified":"2025-12-09T09:49:52","modified_gmt":"2025-12-09T08:49:52","slug":"under-alien-skies","status":"publish","type":"post","link":"https:\/\/www.futuribles.com\/en\/under-alien-skies\/","title":{"rendered":"Under Alien Skies"},"content":{"rendered":"
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In this book, Philip Plait \u2014 an American astronomer and popular science writer \u2014 takes readers on a journey through the cosmos in his spaceship. From lunar regoliths to the event horizon of a black hole, via Saturn\u2019s rings and the Orion Nebula, Under Alien Skies is a book that lives up to its name. The 10 chapters that make up the book follow each other like the different stages of a journey, taking the reader further and further away \u2014 both in space and time \u2014 to discover landscapes that are sometimes breathtaking, sometimes disturbing, but always intriguing. In spite of everything, Under Alien Skies<\/em> remains a work of popular science: Philip Plait ensures, thanks to his pen and his abundant imagination, that his readers not only contemplate, but also understand the workings of the Universe in which they live.<\/h6>
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Plait<\/span> Philip, Under Alien Skies: A Sightseer’s Guide to the Universe,<\/em> New York: Norton, April 2023, 336 p.<\/p>\n\n <\/div>\n \n \n <\/a>\n <\/div>\n \"\"\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n\n\n\n\n

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In the collective imagination, a space tourist leaps onto the ground of a distant planet, wearing his space suit. In this vision we find two of the major constraints associated with a pedestrian excursion to an alien world, largely dealt with in the first five chapters dedicated to our solar system.<\/p>\n

The first constraint is gravity<\/strong>. Since the human body is adapted to the Earth\u2019s gravity, our movements would be much more complicated on other celestial bodies, especially when they are lighter than the Earth. In the chapter on asteroids and comets, for example, we learn that a simple knee bend would produce such an impact on the surface of an asteroid that you would find yourself sunk several metres deep. Strange as it may seem, an asteroid is more like a huge crumbly biscuit than a compact block of rock. Only gas giants like Saturn escape this gravitational problem because, as their name suggests, they are made up of gas, making them impossible to walk on. However, it is interesting to note that Saturn\u2019s rings, although stretching for hundreds of thousands of kilometres, are only about twelve metres thick.<\/p>\n

The second major constraint on an extraterrestrial walk is the atmosphere of the celestial body<\/strong>. That is, if there is one. The Moon and asteroids, for example, have no atmosphere. On Mars and Pluto, the atmosphere is too thin and its composition is unsuitable for the human respiratory system. The spacesuit is therefore the essential piece of equipment for any space tourist. This suit is not only for breathing, but also for maintaining a bearable temperature, which is also influenced by the atmosphere. On Earth, the dense atmosphere retains some of the sun\u2019s heat and warms the planet. This is known as the \u201cgreenhouse effect\u201d. On Mars, for example, the absence of air results in extreme temperatures of -73\u00b0C.<\/p>\n\n <\/div>\n

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\n Voir aussi<\/span>\n
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\n \n \"\"<\/a>\n <\/span>\n \n Space conquest: China and India in the running<\/a>\n \n \n \n <\/use>\n<\/svg>\n <\/a>\n <\/span>\n
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19 November 2024<\/div>\n COU\u00c9 Philippe<\/a>\n
\n 6 min.\n <\/div>\n <\/div>\n\n
\n \n \n <\/use>\n<\/svg>\n\n Newswatch\n <\/a>\n Geopolitics<\/a>\n Science and Technology<\/a>\n <\/div>\n <\/div>\n<\/div>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n
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Philip Plait then takes us beyond the solar system, on a journey through both space and time. In the last five chapters, the kilometre gives way to the light-year \u2014 the distance travelled by light in one year, or about 9,500 billion kilometres. So observing a galaxy 1,000 light-years away is like looking at a photo of it 1,000 years ago, since the light from that galaxy took 1,000 years to reach us. By observing galaxies and nebulae located more than 10 billion light-years away, astronomers are observing the Universe at its origins, just after the Big Bang.<\/p>\n

Planets with two suns, gas jets stretching across hundreds of thousands of light-years. Sometimes frightening, often breathtaking, the cosmos is portrayed as a vast, well-oiled machine. Stars are born in the huge clouds of gas known as nebulae \u2014 such as the famous Orion Nebula \u2014 grow, sometimes devouring each other if they get too close, and then die when they have used up all their fuel. Depending on their mass, this death can be peaceful or dramatic. After burning and swelling throughout its life, when a star with more than eight times the mass of the Sun dies, it collapses in on itself before exploding as a supernova. During this explosion, which is as brief as it is cataclysmic, the matter that makes up the dying star is ejected at extreme speeds, which can result in the birth of a new nebula.<\/p>\n

The journey ends at the edge of a black hole, at the very limits of human understanding. These mysterious bodies, usually located at the centre of galaxies and with a gravity so intense that not even light can escape, would turn any tourist trapped inside them into a \u201cthin stream of vaporised particles\u201d, through a process that astronomers have very seriously named \u201cspaghettification\u201d.<\/p>\n\n <\/div>\n

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\n Voir aussi<\/span>\n
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\n \n \"\"<\/a>\n <\/span>\n \n Fiction as a Way of Debating the Future of Space: The Outcome of an Experiment<\/a>\n \n \n \n <\/use>\n<\/svg>\n <\/a>\n <\/span>\n
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26 April 2019<\/div>\n KAPLAN Daniel<\/a>\n
\n 14 p.\n <\/div>\n <\/div>\n\n
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Under Alien Skies<\/em> is a rich and exciting book that will appeal to novice readers and experienced astronomers alike. Although some passages may require several readings to grasp the physical concepts described, the book is generally easy to read, thanks in particular to the regular and thoughtful alternation between fictional accounts, scientific explanations and elements of the history of science, which \u2014 when embellished with humorous footnotes \u2014 turn Under Alien Skies<\/em> into a genuine initiatory journey through the cosmos.<\/p>\n

However, it is important to remember that the knowledge described in this book is not immutable. Some theories, such as the nature of the core of a black hole, are still being debated within the scientific community. As a result, some of the elements described may prove to be incorrect in the future. Reading this book also raises questions about the societal consequences of uncontrolled space exploration. It seems unlikely that interstellar transport technology would be used solely for tourism. Philip Plait makes this point in his first chapter, when he talks about \u201cmining the south pole\u201d of the Moon. Although the technical advances needed to exploit extraterrestrial resources are currently the stuff of science fiction, the question remains as to what real benefits such technologies would bring to humanity, in a tense geopolitical context and with no ethical, legal or reasoned framework to regulate them. But these societal issues are largely outside the scope of the book, which remains above all a vehicle for the author’s passion for astronomy. And, as he himself points out, \u201cwe can dream, can\u2019t we?\u201d<\/p>\n

\u2014\u2014\u2014\u2014\u2014\u2014\u2013<\/span>
\nN.B.:<\/em> this article has been translated from French by DeepL, and revised by the author and Futuribles.<\/span><\/p>\n\n <\/div>\n

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\n Voir aussi<\/span>\n
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\n \n \"\"<\/a>\n <\/span>\n \n Will the Food of the Future Come from Space?<\/a>\n \n \n \n <\/use>\n<\/svg>\n <\/a>\n <\/span>\n
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29 August 2023<\/div>\n NAVARRO Gr\u00e9gory<\/a>\n
\n 8 min.\n <\/div>\n <\/div>\n\n
\n \n \n <\/use>\n<\/svg>\n\n Interview\n <\/a>\n Environment<\/a>\n Science and Technology<\/a>\n Society<\/a>\n <\/div>\n <\/div>\n<\/div>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n
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In this book, Philip Plait \u2014 an American astronomer and popular science writer \u2014 takes readers on a journey through the cosmos in his spaceship. From lunar regoliths to the event horizon of a black hole, via Saturn\u2019s rings and the Orion Nebula, Under Alien Skies is a book that lives up to its name. … Continued<\/a><\/p>\n","protected":false},"author":25,"featured_media":110351,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"none","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"both","_seopress_redirections_param":"","_seopress_redirections_type":301,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[131],"tags":[210],"keyword":[2550,1265,1044],"class_list":["post-104963","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-read-seen-heard","tag-science-et-technique-en","keyword-astronomy","keyword-sciences-de-l-espace-en","keyword-techniques-spatiales-en"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/posts\/104963","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/comments?post=104963"}],"version-history":[{"count":5,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/posts\/104963\/revisions"}],"predecessor-version":[{"id":121695,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/posts\/104963\/revisions\/121695"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/media\/110351"}],"wp:attachment":[{"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/media?parent=104963"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/categories?post=104963"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/tags?post=104963"},{"taxonomy":"keyword","embeddable":true,"href":"https:\/\/www.futuribles.com\/en\/wp-json\/wp\/v2\/keyword?post=104963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}