{"page":"\u003clink rel=\"stylesheet\" href=\"https://lessonplanet.com/assets/packs/css/resources-c03aa079.css\" /\u003e\n\u003clink rel=\"stylesheet\" href=\"https://lessonplanet.com/assets/packs/css/lp_boclips_stylesheets-517835be.css\" media=\"all\" /\u003e\n\u003cdiv data-title='Tracing the History of Starlight with NASA\u0026#39;s Fermi Mission' data-url='/boclips/videos/6280ea7d00d7e2096956c463' data-video-url='/boclips/videos/6280ea7d00d7e2096956c463' id='bo_player_modal'\u003e\n\u003cdiv class='boclips-resource-page modal-dialog panel-container'\u003e\n\u003cdiv class='react-notifications-root'\u003e\u003c/div\u003e\n\u003cdiv class='rp-header'\u003e\n\u003cdiv class='rp-type'\u003e\n\u003ci aria-hidden='true' class='fai fa-regular fa-circle-play'\u003e\u003c/i\u003e\nVideo\n\u003c/div\u003e\n\u003ch1 class='rp-title' id='video-title'\u003e\nTracing the History of Starlight with NASA\u0026#39;s Fermi Mission\n\u003c/h1\u003e\n\u003cdiv class='rp-actions'\u003e\n\u003cdiv class='mr-1'\u003e\n\u003ca class=\"btn btn-success\" data-posthog-event=\"Signup: LP Signup Activity\" data-posthog-location=\"body_link_boclips\" data-remote=\"true\" href=\"/subscription/new\"\u003e\u003cspan\u003e\u003cspan\u003eGet Free Access\u003c/span\u003e\u003cspan class=\"\"\u003e for 10 Days\u003c/span\u003e\u003cspan\u003e!\u003c/span\u003e\u003c/span\u003e\u003c/a\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class='rp-body'\u003e\n\u003cdiv class='rp-info'\u003e\n\u003cdiv aria-label='Hide resource details' class='rp-hide-info' role='button' tabindex='0'\u003e\u0026times;\u003c/div\u003e\n\u003ci aria-label='Expand resource details' class='rp-expand-info fai fa-solid fa-up-right-and-down-left-from-center' role='button' tabindex='0'\u003e\u003c/i\u003e\n\u003ci aria-label='Compress resource details' class='rp-compress-info fai fa-solid fa-down-left-and-up-right-to-center' role='button' tabindex='0'\u003e\u003c/i\u003e\n\u003cdiv class='rp-rating'\u003e\n\u003cspan class='resource-pool'\u003e\n\u003cspan class='pool-label'\u003ePublisher:\u003c/span\u003e\n\u003cspan class='pool-name'\u003e\n\u003cspan class='text'\u003e\u003ca data-publisher-id=\"384398\" href=\"/search?publisher_ids%5B%5D=384398\"\u003eNASA\u003c/a\u003e\u003c/span\u003e\n\u003c/span\u003e\n\u003c/span\u003e\n\u003c/div\u003e\n\u003cdiv class='rp-description'\u003e\n\u003cspan class='short-description'\u003eScientists using data from NASA's Fermi Gamma-ray Space Telescope have measured all the starlight produced over 90 percent of the universe's history. The analysis, which examines the gamma-ray output of distant galaxies, estimates the...\u003c/span\u003e\n\u003cspan class='full-description hide'\u003eScientists using data from NASA's Fermi Gamma-ray Space Telescope have measured all the starlight produced over 90 percent of the universe's history. The analysis, which examines the gamma-ray output of distant galaxies, estimates the formation rate of stars and provides a reference for future missions that will explore the still-murky early days of stellar evolution.\u003cbr/\u003e\u003cbr/\u003eOne of the main goals of the Fermi mission is to assess the extragalactic background light (EBL), a cosmic fog composed of all the ultraviolet, visible and infrared light stars have created over the universe's history. Because starlight continues to travel across the cosmos long after its sources have burned out, measuring the EBL allows astronomers to study stellar formation and evolution separately from the stars themselves.\u003cbr/\u003e\u003cbr/\u003eThe collision between a high-energy gamma ray and infrared light transforms the energy into a pair of particles, an electron and its antimatter counterpart, a positron. The same process occurs when medium-energy gamma rays interact with visible light, and low-energy gamma rays interact with ultraviolet light. Enough of these interactions occur over cosmic distances that the farther back scientists look, the more evident their effects become on gamma-ray sources, enabling a deep probe of the universe's stellar content.\u003cbr/\u003e\u003cbr/\u003eThe scientists examined gamma-ray signals from 739 blazars -- galaxies with monster black holes at their centers -- collected over nine years by Fermi's Large Area Telescope (LAT). The measurement quintuples the number of blazars used in an earlier Fermi EBL analysis published in 2012 and includes new calculations of how the EBL builds over time, revealing the peak of star formation around 10 billion years ago.\u003cbr/\u003e\u003cbr/\u003eMusic: \"Inducing Waves\" from Killer Tracks\u003cbr/\u003e\u003cbr/\u003eCredit: NASA's Goddard Space Flight Center\u003cbr/\u003eScott Wiessinger (USRA): Lead Producer\u003cbr/\u003eJeanette Kazmierczak (University of Maryland College Park): Lead Science Writer\u003cbr/\u003eLK Ward (USRA): Narrator\u003cbr/\u003eFrancis Reddy (University of Maryland College Park): Science Writer\u003cbr/\u003e\u003cbr/\u003e\u003cbr/\u003e\u003cbr/\u003e\u003cbr/\u003e\u003cbr/\u003e \u003cbr/\u003e   \u003cbr/\u003e \u003cbr/\u003e\u003c/span\u003e\n\u003c/div\u003e\n\u003cdiv class='action-container flex justify-between'\u003e\n\u003cbutton aria-expanded='false' aria-label='Read more description' class='rp-full-description' 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href=\"/search?grade_ids%5B%5D=249\u0026amp;grade_ids%5B%5D=250\u0026amp;grade_ids%5B%5D=251\u0026amp;grade_ids%5B%5D=252\u0026amp;grade_ids%5B%5D=253\u0026amp;grade_ids%5B%5D=254\u0026amp;grade_ids%5B%5D=255\u0026amp;grade_ids%5B%5D=256\u0026amp;grade_ids%5B%5D=257\u0026amp;search_tab_id=2\u0026amp;type_ids%5B%5D=4543647\"\u003eInstructional Videos\u003c/a\u003e\u003c/span\u003e\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cdiv class='detail'\u003e\n\u003cdl\u003e\n\u003cdt\u003eSource:\u003c/dt\u003e\n\u003cdiv class='preview-source' data-animation='true' data-boundary='.rp-info' data-container='.rp-resource-details' data-html='false' data-title='NASA\u0026#39;s Goddard Space Flight Center is home to the nation\u0026#39;s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study Earth, the sun, our solar system and the universe.' data-trigger='hover focus'\u003e\n\u003cspan\u003eNASA 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