{"id":414,"date":"2022-03-24T13:33:57","date_gmt":"2022-03-24T12:33:57","guid":{"rendered":"https:\/\/www.eovision.at\/esa-schoolatlas\/?page_id=414"},"modified":"2025-03-03T13:55:43","modified_gmt":"2025-03-03T12:55:43","slug":"spectral-information","status":"publish","type":"page","link":"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/remotesensing\/spectral-information\/","title":{"rendered":"Spectral Information"},"content":{"rendered":"<h2><a class=\"glossaryLink\" title=\"Glossary: satellite\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;satellite&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A free-flying object orbiting the Earth, another planet, or the sun.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/satellite\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Satellite<\/a> Image Bands<\/h2>\n<p><iframe src=\"https:\/\/esa-schoolatlas.eu\/wp-content\/gismaps_maps\/rsp09_rawbands\/index.html\" width=\"100%\" height=\"665\"><\/iframe><\/p>\n<p>So-called passive satellite systems record the part of the <a class=\"glossaryLink\" title=\"Glossary: solar radiation\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;solar radiation&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Electromagnetic energy received from the sun. The energy comes from different parts of the spectrum, such as visible light, radio waves, infrared, ultraviolet waves, and x-rays.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/solar-radiation\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">solar radiation<\/a> that is reflected from the observed objects, in most cases features on the Earth surface. Satellites acquire data in specific <strong>spectral bands<\/strong>, parts of the <a class=\"glossaryLink\" title=\"Glossary: electromagnetic spectrum\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;electromagnetic spectrum&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The entire range of radiant energies or wave frequencies from the longest to the shortest wavelengths. The spectrum usually is divided into seven sections: radio, microwave, infrared, visible, ultraviolet, x-ray, and gamma-ray radiation.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/electromagnetic-spectrum\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">electromagnetic spectrum<\/a> that can be characterised by a central <a class=\"glossaryLink\" title=\"Glossary: wavelength\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;wavelength&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Spatial distance between two maxima of a wave.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/wavelength\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">wavelength<\/a> and a <a class=\"glossaryLink\" title=\"Glossary: bandwidth\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;bandwidth&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The total range of frequency required to pass a specific modu&#xAC;lated signal without distortion or loss of data.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/bandwidth\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">bandwidth<\/a>.<\/p>\n<p>Optical satellites are operating in the range from the <strong>visible <\/strong>part of the spectrum (wavelength 400-700 nm) to the <strong>infrared <\/strong>part (from the so-called <a class=\"glossaryLink\" title=\"Glossary: near infrared\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;near infrared&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;NIR: Electromagnetic radiation with wavelengths from just longer than the visible (about 0.7 &#x3BC;m) to about 2 &#x3BC;m.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/near-infrared\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Near Infrared<\/a>, <a class=\"glossaryLink\"  title=\"Glossary: NIR\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;NIR&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Near infrared. Electromagnetic radiation with wavelengths from just longer than the visible (about 0.7 &mu;m) to about 2 &mu;m.&lt;\/div&gt;\"  href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/nir\/\"  target=\"_blank\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>NIR<\/a>, from 700 nm to 2 &micro;m, and <a class=\"glossaryLink\" title=\"Glossary: middle infrared\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;middle infrared&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Electromagnetic radiation between the near infrared and the thermal infrared, about 2-5 &#x3BC;m.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/middle-infrared\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Middle Infrared<\/a>, MIR, from 2 to 5 &#xB5;m, to <a class=\"glossaryLink\" title=\"Glossary: far infrared\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;far infrared&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Part of the electromagnetic spectrum with wavelengths longer than the thermal infrared, between about 25 and 1000 micrometres.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/far-infrared\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Far Infrared<\/a>, FIR, 25 to 1000 &#xB5;m). A special part of the infrared spectrum is the <a class=\"glossaryLink\" title=\"Glossary: thermal infrared\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;thermal infrared&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Electromagnetic radiation with wavelengths between 3 and 25 &#xB5;m (TIR).&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/thermal-infrared\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Thermal Infrared<\/a>, TIR, with wavelengths between 3 and 25 &#xB5;m.<\/p>\n<p>The human eye has receptors that are sensitive for <a class=\"glossaryLink\" title=\"Glossary: radiation\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;radiation&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Energy transfer in the form of electromagnetic waves or particles that release energy when absorbed by an object.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/radiation\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">radiation<\/a> in the blue, green, and red parts of the spectrum. We see objects in different colours depending on differences in the light emission or <a class=\"glossaryLink\" title=\"Glossary: reflection\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;reflection&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The return of light or sound waves from a surface. If a reflecting surface is plane, the angle of reflection of a light ray is the same as the angle of incidence.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/reflection\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">reflection<\/a> by these objects. In the same way objects on the Earth&#x2019;s surface reflect sunlight differently depending on the material they consist of and on its status.<\/p>\n<p>The examples show image bands of the satellite <a class=\"glossaryLink\" title=\"Glossary: Sentinel\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Sentinel&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Series of six different Earth Observation satellite types under responsibility of ESA in the Copernicus programme.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/sentinel\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Sentinel<\/a>-2, which acquires data in bands with central wavelengths ranging from 443 nm to 2.19 &#xB5;m. For comparison, a true-colour image prepared from the bands in the visible range of the spectrum has been added on the next page to make the interpretation of the visible objects easier.<\/p>\n<p>Comparison with the true-colour image shows, why the sea water appears in blue &ndash; especially the blue <a class=\"glossaryLink\"  title=\"Glossary: band\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;band&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A region of the electromagnetic spectrum to which a remote sensor responds; a multispectral sensor makes measurements in a number of spectral bands.&lt;\/div&gt;\"  href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/band\/\"  target=\"_blank\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>band<\/a> is relatively bright, while in the red band the water appears dark. Combined, this results in a light blue colour. Similar considerations can be made with other landcover classes: forests, fields, cropland, and built-up areas such as towns and traffic infrastructure (look at the airport Fiumicino to the left of the images!).<\/p>\n<p>The human eye and mind are very efficient with respect to interpreting true-colour images. Special algorithms applied to the data allow to extract a wealth of additional information that would not be accessible to the human perception otherwise.<\/p>\n<p style=\"text-align: center;\"><img decoding=\"async\" class=\"alignnone size-large wp-image-2334\" src=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-930x541.jpg\" alt=\"\" width=\"60%\" srcset=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-930x541.jpg 930w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-610x355.jpg 610w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-768x447.jpg 768w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-1536x893.jpg 1536w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-258x150.jpg 258w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-1600x931.jpg 1600w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-400x233.jpg 400w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-300x174.jpg 300w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN-600x349.jpg 600w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2025\/02\/EOFromSpace_spectra_mod_fig_EN.jpg 1654w\" sizes=\"(max-width: 930px) 100vw, 930px\"\/><br>\n<em>Diagram showing the electromagnetic spectrum, <a class=\"glossaryLink\" title=\"Glossary: reflectance\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;reflectance&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The proportion of irradiated electromagnetic radiation reflected by a surface.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/reflectance\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">reflectance<\/a> curves for selected <a class=\"glossaryLink\" title=\"Glossary: land cover\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;land cover&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The characteristics of a land surface as determined by its spectral signature (the unique way in which a given type of land cover reflects and absorbs light).&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/land-cover\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">land cover<\/a> classes (top), the atmospheric transmission (middle), and where the bands of selected satellites are located (bottom). Note: the x-axis is logarithmic, i.e. with each red line the wavelength increases by a factor of 10.<\/em><\/p>\n<p>&#xA0;<\/p>\n<h3>Exercises<\/h3>\n<ul>\n<li><strong>Satellite Map:<\/strong>\n<ul>\n<li>Use the layer selector to look at the different satellite bands of the Sentinel-2 data. Compare them with the true-colour image and try to identify the <a class=\"glossaryLink\" title=\"Glossary: land use\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;land use&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The characteristics of a land surface as determined by its use (the unique way in which a given type of land is &#x2013; or is not &#x2013; exploited by man).&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/land-use\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">land use<\/a> and landcover classes in the region.<\/li>\n<li>Try to identify forests (note: forests appear in dark green or brown colours, e.g. in the lower centre of the images; therefore, they are dark in the visible bands).<\/li>\n<li>Look at the water bodies (sea, river). How do they appear in the individual image bands?<\/li>\n<li>For advanced readers: compare the land cover classes identified in the images (especially water and vegetation) with the spectral reflectance curves in the upper part of the diagram below and describe your findings (the grey boxes in the line &#x201C;Sentinel-2&#x201D; indicate the locations of the bands, band index starting with 1 for the leftmost band).<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ul>\n<li><strong><a class=\"glossaryLink\" title=\"Glossary: Copernicus\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Copernicus&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Former name GMES (Global Monitoring for Environment and Security), the EU&#x2019;s Copernicus Earth observation programme, comprising in-situ elements (measurement tools) and the space segment (satellites).&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/copernicus\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Copernicus<\/a> Browser:<\/strong>\n<ul>\n<li>Open the case study area in the <a href=\"https:\/\/link.dataspace.copernicus.eu\/czyo\" target=\"_blank\" rel=\"noopener\">Copernicus Browser<\/a>.<\/li>\n<li>Find the most recent Sentinel-2 dataset covering the area displayed in the satellite map.<\/li>\n<li>Select a natural colour representation.<\/li>\n<li>Can you identify additional, recent changes in the area?<\/li>\n<li>Select the <a class=\"glossaryLink\" title=\"Glossary: false colour\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;false colour&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;A colour imaging process which produces an image of a colour that does not correspond to the true or natural colour of the scene (as seen by our eyes). In Earth observation often used e.g. with infrared data (False colour Infrared, FIR).&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/false-colour\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">false colour<\/a> infrared representation. Can you identify the land-use of the most intensely vegetated areas (represented by bright red colours)?<\/li>\n<li>Select the <strong>custom visualisation<\/strong>. Visualize individual bands (you can do this by dragging the same band to R, G, and B fields). Do this for different bands and compare. What are your findings with respect to the representation of different landcover classes (water, agricultural land, built-up land, etc.)?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&#xA0;<\/p>\n<h3>Links and Sources<\/h3>\n<table style=\"background-color: #444444;\">\n<tbody>\n<tr>\n<td style=\"vertical-align: middle; padding-left: 10px;\"><strong>Downloads:<\/strong><\/td>\n<td><\/td>\n<\/tr><tr>\n<td align=\"center\"><img decoding=\"async\" class=\"wp-image-1439\" src=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-150x150.png\" alt=\"\" width=\"25\" height=\"25\" srcset=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-150x150.png 150w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-152x150.png 152w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-80x80.png 80w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-300x300.png 300w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4.png 320w\" sizes=\"(max-width: 25px) 100vw, 25px\"\/><\/td>\n<td>\nPDF document of the case study (includes exercises):<br>\n<a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/RSP09_1_EN_RemoteSensing_Bands.pdf\" target=\"_blank\" rel=\"noopener\">English<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/RSP09_1_DE_RemoteSensing_Bands.pdf\" target=\"_blank\" rel=\"noopener\"> German<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/RSP09_1_FR_RemoteSensing_Bands.pdf\" target=\"_blank\" rel=\"noopener\"> French<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/RSP09_1_IT_RemoteSensing_Bands.pdf\" target=\"_blank\" rel=\"noopener\"> Italian<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/RSP09_1_ES_RemoteSensing_Bands.pdf\" target=\"_blank\" rel=\"noopener\"> Spanish<\/a>\n<\/td>\n<\/tr>\n<tr>\n<td align=\"center\">\n<img decoding=\"async\" class=\"wp-image-1439\" src=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-150x150.png\" alt=\"\" width=\"25\" height=\"25\" srcset=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-150x150.png 150w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-152x150.png 152w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-80x80.png 80w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4-300x300.png 300w, https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/uploads\/sites\/7\/2023\/11\/pdf-icon-4.png 320w\" sizes=\"(max-width: 25px) 100vw, 25px\"\/>\n<\/td>\n<td>\nThis case study is covered on page 18 of the printed <a class=\"glossaryLink\"  title=\"Glossary: ESA\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;ESA&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;The European Space Agency&lt;\/div&gt;\"  href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/esa\/\"  target=\"_blank\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>ESA<\/a> Schoolatlas &ndash; download the PDF document of the page:<br>\n<a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/ESA_Schoolatlas_EN_Page18.pdf\" target=\"_blank\" rel=\"noopener\">English<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/ESA_Schoolatlas_DE_Page18.pdf\" target=\"_blank\" rel=\"noopener\">German<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/ESA_Schoolatlas_FR_Page18.pdf\" target=\"_blank\" rel=\"noopener\">French<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/ESA_Schoolatlas_IT_Page18.pdf\" target=\"_blank\" rel=\"noopener\">Italian<\/a>, <a href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/wp-content\/gismaps_maps\/rsp09_rawbands\/ESA_Schoolatlas_ES_Page18.pdf\" target=\"_blank\" rel=\"noopener\">Spanish<\/a>\n<\/td>\n<\/tr>\n<\/tbody><\/table>\n\n\n\n\n<table style=\"background-color: #444444;\">\n<tbody>\n<tr>\n<td style=\"vertical-align: middle; padding-left: 10px;\"><strong>Links:<\/strong><\/td>\n<\/tr>\n<tr>\n<td style=\"padding-left: 10px;\">\n<ul>\n<li><a href=\"https:\/\/www.esa.int\/Education\/1._Introduction\" target=\"_blank\" rel=\"noopener\">https:\/\/www.esa.int\/Education\/1._Introduction<\/a> &#x2013; <a class=\"glossaryLink\" title=\"Glossary: Earth observation\" aria-describedby=\"tt\" data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;Earth observation&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Observation of the Earth from space, mostly based on satellites.&lt;\/div&gt;\" href=\"https:\/\/esa-schoolatlas.eu\/esa-schoolatlas\/fr\/glossary\/earth-observation\/\" target=\"_blank\" data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]' tabindex=\"0\" role=\"link\">Earth observation<\/a> course for secondary schools.<\/li>\n<\/ul><\/td><\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>Satellite Image Bands So-called passive satellite systems record the part of the solar radiation that is reflected from the observed objects, in most cases features on the Earth surface. Satellites acquire data in specific spectral bands, parts of the electromagnetic spectrum that can be characterised by a central wavelength and a bandwidth. Optical satellites are [&#x2026;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":404,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-414","page","type-page","status-publish","hentry"],"translation":{"provider":"WPGlobus","version":"3.0.0","language":"fr","enabled_languages":["en","es","de","fr","it"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"es":{"title":false,"content":false,"excerpt":false},"de":{"title":true,"content":true,"excerpt":false},"fr":{"title":false,"content":false,"excerpt":false},"it":{"title":false,"content":false,"excerpt":false}}},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>- ESA Schoolatlas<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" 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