{"id":258,"date":"2017-08-08T13:12:16","date_gmt":"2017-08-08T17:12:16","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/chapter\/6-6-the-future-of-large-telescopes\/"},"modified":"2017-12-20T13:44:37","modified_gmt":"2017-12-20T18:44:37","slug":"6-6-the-future-of-large-telescopes","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/chapter\/6-6-the-future-of-large-telescopes\/","title":{"raw":"6.6 The Future of Large Telescopes","rendered":"6.6 The Future of Large Telescopes"},"content":{"raw":"\n<div class=\"bcc-box bcc-highlight\">\n<h3>Learning Objectives<\/h3>\n<p id=\"fs-id1168583995213\">By the end of this section, you will be able to:<\/p>\n<ul id=\"fs-id1167470624238\">\n<li>Describe the next generation of ground- and space-based observatories<\/li>\n<li>Explain some of the challenges involved in building these observatories<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-id1167470757058\">If you\u2019ve ever gone on a hike, you have probably been eager to see what lies just around the next bend in the path. Researchers are no different, and astronomers and engineers are working on the technologies that will allow us to explore even more distant parts of the universe and to see them more clearly.<\/p>\n<p id=\"fs-id1167470602191\">The premier space facility planned for the next decade is the <span class=\"no-emphasis\">James Webb Space Telescope<\/span> (<a href=\"#OSC_Astro_06_06_JWST\" class=\"autogenerated-content\">[link]<\/a>), which (in a departure from tradition) is named after one of the early administrators of NASA instead of a scientist. This telescope will have a mirror 6 meters in diameter, made up, like the Keck telescopes, of 36 small hexagons. These will have to unfold into place once the telescope reaches its stable orbit point, some 1.5 million kilometers from Earth (where no astronauts can currently travel if it needs repair.) The telescope is scheduled for launch in 2018 and should have the sensitivity needed to detect the very first generation of stars, formed when the universe was only a few hundred million years old. With the ability to measure both visible and infrared wavelengths, it will serve as the successor to both HST and the Spitzer Space Telescope.<\/p>\n<figure id=\"OSC_Astro_06_06_JWST\">\n<div class=\"title\" style=\"text-align: center\"><strong>James Webb Space Telescope (JWST).<\/strong><\/div>\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/practicalphysics1104\/wp-content\/uploads\/sites\/302\/2017\/08\/OSC_Astro_06_06_JWST-1.jpg\" alt=\"Photograph of the cryogenic mirror testing assembly and 6 of the hexagonal mirror segments of the James Webb Space Telescope. A technician is seen inspecting the right-most mirror segment.\" width=\"487\" height=\"324\"> <strong>Figure 1.<\/strong> This image shows some of the mirrors of the JWST as they underwent cryogenic testing. The mirrors were exposed to extreme temperatures in order to gather accurate measurements on changes in their shape as they heated and cooled. (credit: NASA\/MSFC\/David Higginbotham\/Emmett Given)[\/caption]<\/figure>\n<div id=\"fs-id1167471083052\" class=\"note astronomy link-to-learning\">\n<div class=\"textbox shaded\">Watch this <a href=\"https:\/\/openstaxcollege.org\/l\/30JWSTvid\">video<\/a> to learn more about the James Webb Space Telescope and how it will build upon the work that Hubble has allowed us to begin in exploring the universe.<\/div>\n<\/div>\n<p id=\"fs-id1167470923512\">On the ground, astronomers have started building the <span class=\"no-emphasis\">Large Synoptic Survey Telescope<\/span> (LSST), an 8.4-meter telescope with a significantly larger field of view than any existing telescopes. It will rapidly scan the sky to find <em>transients<\/em>, phenomena that change quickly, such as exploding stars and chunks of rock that orbit near Earth. The LSST is expected to see first light in 2021.<\/p>\n<p id=\"fs-id1167470606203\">The international gamma-ray community is planning the <span class=\"no-emphasis\">Cherenkov Telescope Array<\/span> (CTA), two arrays of telescopes, one in each hemisphere, which will indirectly measure gamma rays from the ground. The CTA will measure gamma-ray energies a thousand times as great as the Fermi telescope can detect.<\/p>\n<p id=\"fs-id1167470761058\">Several groups of astronomers around the globe interested in studying visible light and infrared are exploring the feasibility of building ground-based telescopes with mirrors larger than 30 meters across. Stop and think what this means: 30 meters is one-third the length of a football field. It is technically impossible to build and transport a single astronomical mirror that is 30 meters or larger in diameter. The primary mirror of these giant telescopes will consist of smaller mirrors, all aligned so that they act as a very large mirror in combination. These include the Thirty-Meter Telescope for which construction has begun at the top of Mauna Kea in Hawaii.<\/p>\n<p id=\"fs-id1167471061491\">The most ambitious of these projects is the <span class=\"no-emphasis\">European Extremely Large Telescope<\/span> (E-ELT) (<a href=\"#OSC_Astro_06_06_Conception\" class=\"autogenerated-content\">[link]<\/a>). (Astronomers try to outdo each other not only with the size of these telescopes, but also their names!) The design of the E-ELT calls for a 39.3-meter primary mirror, which will follow the Keck design and be made up of 798 hexagonal mirrors, each 1.4 meters in diameter and all held precisely in position so that they form a continuous surface.<\/p>\n<p>Construction on the site in the Atacama Desert in Northern Chile started in 2014. The E-ELT, along with the Thirty Meter Telescope and the Giant Magellan Telescope, which are being built by international consortia led by US astronomers, will combine light-gathering power with high-resolution imaging. These powerful new instruments will enable astronomers to tackle many important astronomical problems. For example, they should be able to tell us when, where, and how often planets form around other stars. They should even be able to provide us images and spectra of such planets and thus, perhaps, give us the first real evidence (from the chemistry of these planets\u2019 atmospheres) that life exists elsewhere.<\/p>\n<figure id=\"OSC_Astro_06_06_Conception\">\n<div class=\"title\" style=\"text-align: center\"><strong>Artist\u2019s Conception of the European Extremely Large Telescope.<\/strong><\/div>\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/practicalphysics1104\/wp-content\/uploads\/sites\/302\/2017\/08\/OSC_Astro_06_06_Conception-1.jpg\" alt=\"Illustration of the European Extremely Large Telescope seen through the open dome of the building, and the surrounding desert landscape in Chile.\" width=\"487\" height=\"274\"> <strong>Figure 2.<\/strong> The primary mirror in this telescope is 39.3 meters across. The telescope is under construction in the Atacama Desert in Northern Chile. (credit: ESO\/L. Cal\u00e7ada)[\/caption]<\/figure>\n<div id=\"fs-id1167470700235\" class=\"note astronomy link-to-learning\">\n<div class=\"textbox shaded\">Check out this <a href=\"https:\/\/openstaxcollege.org\/l\/30JWSTdiag\">fun diagram<\/a> comparing the sizes of the largest planned and existing telescopes to a regulation basketball and tennis court.<\/div>\n<\/div>\n<section id=\"fs-id1167470625224\" class=\"summary\">\n<p id=\"fs-id1167470625677\">New and even larger telescopes are on the drawing boards. The James Webb Space Telescope, a 6-meter successor to Hubble, is currently scheduled for launch in 2018. Gamma-ray astronomers are planning to build the CTA to measure very energetic gamma rays. Astronomers are building the LSST to observe with an unprecedented field of view and a new generation of visible-light\/infrared telescopes with apertures of 24.5 to 39 meters in diameter.<\/p>\n<\/section>\n<section id=\"fs-id1167470964084\" class=\"further-exploration\">\n<h1>For Further Exploration<\/h1>\n<section id=\"eip-id1163976726160\">\n<h2>Articles<\/h2>\n<p id=\"fs-id1167470825466\">Blades, J. C. \u201cFixing the Hubble One Last Time.\u201d <em>Sky &amp; Telescope<\/em> (October 2008): 26. On the last Shuttle service mission and what the Hubble was then capable of doing.<\/p>\n<p id=\"fs-id1167470636355\">Brown, A. \u201cHow Gaia will Map a Billion Stars.\u201d <em>Astronomy<\/em> (December 2014): 32. Nice review of the mission to do photometry and spectroscopy of all stars above a certain brightness.<\/p>\n<p id=\"fs-id1167470969827\">Irion, R. \u201cPrime Time.\u201d <em>Astronomy<\/em> (February 2001): 46. On how time is allotted on the major research telescopes.<\/p>\n<p id=\"fs-id1167470663739\">Jedicke, Peter &amp; Robert. \u201cThe Coming Giant Sky Patrols.\u201d <em>Sky &amp; Telescope<\/em> (September 2008): 30. About giant telescopes to survey the sky continuously.<\/p>\n<p id=\"fs-id1167470770730\">Lazio, Joseph, et al. \u201cTuning in to the Universe: 21<sup>st<\/sup> Century Radio Astronomy.\u201d <em>Sky &amp; Telescope<\/em> (July 2008): 21. About ALMA and the Square Kilometer Array.<\/p>\n<p id=\"fs-id1167470749980\">Lowe, Jonathan. \u201cMirror, Mirror.\u201d <em>Sky &amp; Telescope<\/em> (December 2007): 22. On the Large Binocular Telescope in Arizona.<\/p>\n<p id=\"fs-id1167470762283\">Lowe, Jonathan. \u201cNext Light: Tomorrow\u2019s Monster Telescopes.\u201d <em>Sky &amp; Telescope<\/em> (April 2008): 20. About plans for extremely large telescopes on the ground.<\/p>\n<p id=\"fs-id1167470565664\">Mason, Todd &amp; Robin. \u201cPalomar\u2019s Big Eye.\u201d <em>Sky &amp; Telescope<\/em> (December 2008): 36. On the Hale 200-inch telescope.<\/p>\n<p id=\"fs-id1167470992584\">Subinsky, Raymond. \u201cWho Really Invented the Telescope.\u201d <em>Astronomy<\/em> (August 2008): 84. Brief historical introduction, focusing on Hans Lippershey.<\/p>\n<\/section>\n<section id=\"eip-id1163976548804\">\n<h2>Websites<\/h2>\n<p id=\"fs-id1167470704622\">Websites for major telescopes are given in <a href=\"\/contents\/cbd1efb7-998a-4672-9337-ba9ecf4f8a8d#fs-id1167470615449\" class=\"autogenerated-content\">[link]<\/a>, <a href=\"\/contents\/99df183c-aa08-41b0-b02e-bb641d304cb9#fs-id1167470936824\" class=\"autogenerated-content\">[link]<\/a>, <a href=\"\/contents\/99df183c-aa08-41b0-b02e-bb641d304cb9#fs-id1167470667239\" class=\"autogenerated-content\">[link]<\/a>, and <a href=\"\/contents\/ae35cefe-bf23-40b0-97a8-d174c341e5d8#fs-id1167469604443\" class=\"autogenerated-content\">[link]<\/a>.<\/p>\n<\/section>\n<section id=\"eip-id1163976872619\">\n<h2>Videos<\/h2>\n<p id=\"fs-id1167470616950\">Astronomy from the Stratosphere: SOFIA: https:\/\/www.youtube.com\/watch?v=NV98BcBBA9c. A talk by Dr. Dana Backman (1:15:32)<\/p>\n<p id=\"fs-id1167471082938\">Galaxies Viewed in Full Spectrum of Light: https:\/\/www.youtube.com\/watch?v=368K0iQv8nE. Scientists with the Spitzer Observatory show how a galaxy looks different at different wavelengths (6:22)<\/p>\n<p id=\"fs-id1167470769763\">Lifting the Cosmic Veil: Highlights from a Decade of the Spitzer Space Telescope: https:\/\/www.youtube.com\/watch?v=nkrNQcwkY78. A talk by Dr. Michael Bicay (1:42:44)<\/p>\n<\/section>\n<\/section>\n<section id=\"fs-id1167470995318\" class=\"group-activities\"><\/section>\n<section id=\"fs-id1167470754765\" class=\"figuring-for-yourself\">\n<div class=\"exercise\" id=\"fs-id1167470670621\">\n<div class=\"problem\" id=\"fs-id1167470670623\">\n<p id=\"fs-id1167470772591\">\n<\/p><\/div>\n<\/div>\n<\/section>\n\n","rendered":"<div class=\"bcc-box bcc-highlight\">\n<h3>Learning Objectives<\/h3>\n<p id=\"fs-id1168583995213\">By the end of this section, you will be able to:<\/p>\n<ul id=\"fs-id1167470624238\">\n<li>Describe the next generation of ground- and space-based observatories<\/li>\n<li>Explain some of the challenges involved in building these observatories<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-id1167470757058\">If you\u2019ve ever gone on a hike, you have probably been eager to see what lies just around the next bend in the path. Researchers are no different, and astronomers and engineers are working on the technologies that will allow us to explore even more distant parts of the universe and to see them more clearly.<\/p>\n<p id=\"fs-id1167470602191\">The premier space facility planned for the next decade is the <span class=\"no-emphasis\">James Webb Space Telescope<\/span> (<a href=\"#OSC_Astro_06_06_JWST\" class=\"autogenerated-content\">[link]<\/a>), which (in a departure from tradition) is named after one of the early administrators of NASA instead of a scientist. This telescope will have a mirror 6 meters in diameter, made up, like the Keck telescopes, of 36 small hexagons. These will have to unfold into place once the telescope reaches its stable orbit point, some 1.5 million kilometers from Earth (where no astronauts can currently travel if it needs repair.) The telescope is scheduled for launch in 2018 and should have the sensitivity needed to detect the very first generation of stars, formed when the universe was only a few hundred million years old. With the ability to measure both visible and infrared wavelengths, it will serve as the successor to both HST and the Spitzer Space Telescope.<\/p>\n<figure id=\"OSC_Astro_06_06_JWST\">\n<div class=\"title\" style=\"text-align: center\"><strong>James Webb Space Telescope (JWST).<\/strong><\/div>\n<figure style=\"width: 487px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/practicalphysics1104\/wp-content\/uploads\/sites\/302\/2017\/08\/OSC_Astro_06_06_JWST-1.jpg\" alt=\"Photograph of the cryogenic mirror testing assembly and 6 of the hexagonal mirror segments of the James Webb Space Telescope. A technician is seen inspecting the right-most mirror segment.\" width=\"487\" height=\"324\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 1.<\/strong> This image shows some of the mirrors of the JWST as they underwent cryogenic testing. The mirrors were exposed to extreme temperatures in order to gather accurate measurements on changes in their shape as they heated and cooled. (credit: NASA\/MSFC\/David Higginbotham\/Emmett Given)<\/figcaption><\/figure>\n<\/figure>\n<div id=\"fs-id1167471083052\" class=\"note astronomy link-to-learning\">\n<div class=\"textbox shaded\">Watch this <a href=\"https:\/\/openstaxcollege.org\/l\/30JWSTvid\">video<\/a> to learn more about the James Webb Space Telescope and how it will build upon the work that Hubble has allowed us to begin in exploring the universe.<\/div>\n<\/div>\n<p id=\"fs-id1167470923512\">On the ground, astronomers have started building the <span class=\"no-emphasis\">Large Synoptic Survey Telescope<\/span> (LSST), an 8.4-meter telescope with a significantly larger field of view than any existing telescopes. It will rapidly scan the sky to find <em>transients<\/em>, phenomena that change quickly, such as exploding stars and chunks of rock that orbit near Earth. The LSST is expected to see first light in 2021.<\/p>\n<p id=\"fs-id1167470606203\">The international gamma-ray community is planning the <span class=\"no-emphasis\">Cherenkov Telescope Array<\/span> (CTA), two arrays of telescopes, one in each hemisphere, which will indirectly measure gamma rays from the ground. The CTA will measure gamma-ray energies a thousand times as great as the Fermi telescope can detect.<\/p>\n<p id=\"fs-id1167470761058\">Several groups of astronomers around the globe interested in studying visible light and infrared are exploring the feasibility of building ground-based telescopes with mirrors larger than 30 meters across. Stop and think what this means: 30 meters is one-third the length of a football field. It is technically impossible to build and transport a single astronomical mirror that is 30 meters or larger in diameter. The primary mirror of these giant telescopes will consist of smaller mirrors, all aligned so that they act as a very large mirror in combination. These include the Thirty-Meter Telescope for which construction has begun at the top of Mauna Kea in Hawaii.<\/p>\n<p id=\"fs-id1167471061491\">The most ambitious of these projects is the <span class=\"no-emphasis\">European Extremely Large Telescope<\/span> (E-ELT) (<a href=\"#OSC_Astro_06_06_Conception\" class=\"autogenerated-content\">[link]<\/a>). (Astronomers try to outdo each other not only with the size of these telescopes, but also their names!) The design of the E-ELT calls for a 39.3-meter primary mirror, which will follow the Keck design and be made up of 798 hexagonal mirrors, each 1.4 meters in diameter and all held precisely in position so that they form a continuous surface.<\/p>\n<p>Construction on the site in the Atacama Desert in Northern Chile started in 2014. The E-ELT, along with the Thirty Meter Telescope and the Giant Magellan Telescope, which are being built by international consortia led by US astronomers, will combine light-gathering power with high-resolution imaging. These powerful new instruments will enable astronomers to tackle many important astronomical problems. For example, they should be able to tell us when, where, and how often planets form around other stars. They should even be able to provide us images and spectra of such planets and thus, perhaps, give us the first real evidence (from the chemistry of these planets\u2019 atmospheres) that life exists elsewhere.<\/p>\n<figure id=\"OSC_Astro_06_06_Conception\">\n<div class=\"title\" style=\"text-align: center\"><strong>Artist\u2019s Conception of the European Extremely Large Telescope.<\/strong><\/div>\n<figure style=\"width: 487px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/practicalphysics1104\/wp-content\/uploads\/sites\/302\/2017\/08\/OSC_Astro_06_06_Conception-1.jpg\" alt=\"Illustration of the European Extremely Large Telescope seen through the open dome of the building, and the surrounding desert landscape in Chile.\" width=\"487\" height=\"274\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 2.<\/strong> The primary mirror in this telescope is 39.3 meters across. The telescope is under construction in the Atacama Desert in Northern Chile. (credit: ESO\/L. Cal\u00e7ada)<\/figcaption><\/figure>\n<\/figure>\n<div id=\"fs-id1167470700235\" class=\"note astronomy link-to-learning\">\n<div class=\"textbox shaded\">Check out this <a href=\"https:\/\/openstaxcollege.org\/l\/30JWSTdiag\">fun diagram<\/a> comparing the sizes of the largest planned and existing telescopes to a regulation basketball and tennis court.<\/div>\n<\/div>\n<section id=\"fs-id1167470625224\" class=\"summary\">\n<p id=\"fs-id1167470625677\">New and even larger telescopes are on the drawing boards. The James Webb Space Telescope, a 6-meter successor to Hubble, is currently scheduled for launch in 2018. Gamma-ray astronomers are planning to build the CTA to measure very energetic gamma rays. Astronomers are building the LSST to observe with an unprecedented field of view and a new generation of visible-light\/infrared telescopes with apertures of 24.5 to 39 meters in diameter.<\/p>\n<\/section>\n<section id=\"fs-id1167470964084\" class=\"further-exploration\">\n<h1>For Further Exploration<\/h1>\n<section id=\"eip-id1163976726160\">\n<h2>Articles<\/h2>\n<p id=\"fs-id1167470825466\">Blades, J. C. \u201cFixing the Hubble One Last Time.\u201d <em>Sky &amp; Telescope<\/em> (October 2008): 26. On the last Shuttle service mission and what the Hubble was then capable of doing.<\/p>\n<p id=\"fs-id1167470636355\">Brown, A. \u201cHow Gaia will Map a Billion Stars.\u201d <em>Astronomy<\/em> (December 2014): 32. Nice review of the mission to do photometry and spectroscopy of all stars above a certain brightness.<\/p>\n<p id=\"fs-id1167470969827\">Irion, R. \u201cPrime Time.\u201d <em>Astronomy<\/em> (February 2001): 46. On how time is allotted on the major research telescopes.<\/p>\n<p id=\"fs-id1167470663739\">Jedicke, Peter &amp; Robert. \u201cThe Coming Giant Sky Patrols.\u201d <em>Sky &amp; Telescope<\/em> (September 2008): 30. About giant telescopes to survey the sky continuously.<\/p>\n<p id=\"fs-id1167470770730\">Lazio, Joseph, et al. \u201cTuning in to the Universe: 21<sup>st<\/sup> Century Radio Astronomy.\u201d <em>Sky &amp; Telescope<\/em> (July 2008): 21. About ALMA and the Square Kilometer Array.<\/p>\n<p id=\"fs-id1167470749980\">Lowe, Jonathan. \u201cMirror, Mirror.\u201d <em>Sky &amp; Telescope<\/em> (December 2007): 22. On the Large Binocular Telescope in Arizona.<\/p>\n<p id=\"fs-id1167470762283\">Lowe, Jonathan. \u201cNext Light: Tomorrow\u2019s Monster Telescopes.\u201d <em>Sky &amp; Telescope<\/em> (April 2008): 20. About plans for extremely large telescopes on the ground.<\/p>\n<p id=\"fs-id1167470565664\">Mason, Todd &amp; Robin. \u201cPalomar\u2019s Big Eye.\u201d <em>Sky &amp; Telescope<\/em> (December 2008): 36. On the Hale 200-inch telescope.<\/p>\n<p id=\"fs-id1167470992584\">Subinsky, Raymond. \u201cWho Really Invented the Telescope.\u201d <em>Astronomy<\/em> (August 2008): 84. Brief historical introduction, focusing on Hans Lippershey.<\/p>\n<\/section>\n<section id=\"eip-id1163976548804\">\n<h2>Websites<\/h2>\n<p id=\"fs-id1167470704622\">Websites for major telescopes are given in <a href=\"\/contents\/cbd1efb7-998a-4672-9337-ba9ecf4f8a8d#fs-id1167470615449\" class=\"autogenerated-content\">[link]<\/a>, <a href=\"\/contents\/99df183c-aa08-41b0-b02e-bb641d304cb9#fs-id1167470936824\" class=\"autogenerated-content\">[link]<\/a>, <a href=\"\/contents\/99df183c-aa08-41b0-b02e-bb641d304cb9#fs-id1167470667239\" class=\"autogenerated-content\">[link]<\/a>, and <a href=\"\/contents\/ae35cefe-bf23-40b0-97a8-d174c341e5d8#fs-id1167469604443\" class=\"autogenerated-content\">[link]<\/a>.<\/p>\n<\/section>\n<section id=\"eip-id1163976872619\">\n<h2>Videos<\/h2>\n<p id=\"fs-id1167470616950\">Astronomy from the Stratosphere: SOFIA: https:\/\/www.youtube.com\/watch?v=NV98BcBBA9c. A talk by Dr. Dana Backman (1:15:32)<\/p>\n<p id=\"fs-id1167471082938\">Galaxies Viewed in Full Spectrum of Light: https:\/\/www.youtube.com\/watch?v=368K0iQv8nE. Scientists with the Spitzer Observatory show how a galaxy looks different at different wavelengths (6:22)<\/p>\n<p id=\"fs-id1167470769763\">Lifting the Cosmic Veil: Highlights from a Decade of the Spitzer Space Telescope: https:\/\/www.youtube.com\/watch?v=nkrNQcwkY78. A talk by Dr. Michael Bicay (1:42:44)<\/p>\n<\/section>\n<\/section>\n<section id=\"fs-id1167470995318\" class=\"group-activities\"><\/section>\n<section id=\"fs-id1167470754765\" class=\"figuring-for-yourself\">\n<div class=\"exercise\" id=\"fs-id1167470670621\">\n<div class=\"problem\" id=\"fs-id1167470670623\">\n<p id=\"fs-id1167470772591\">\n<\/div>\n<\/div>\n<\/section>\n","protected":false},"author":61,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-258","chapter","type-chapter","status-publish","hentry"],"part":216,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapters\/258","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/wp\/v2\/users\/61"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapters\/258\/revisions"}],"predecessor-version":[{"id":259,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapters\/258\/revisions\/259"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/parts\/216"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapters\/258\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/wp\/v2\/media?parent=258"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/pressbooks\/v2\/chapter-type?post=258"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/wp\/v2\/contributor?post=258"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/astronomy1105dl\/wp-json\/wp\/v2\/license?post=258"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}