From db8e598e9adf4d737261e8121e899df8981baf9b Mon Sep 17 00:00:00 2001 From: Nicolas Giard Date: Mon, 20 Aug 2018 01:02:57 -0400 Subject: [PATCH] feat: page display + renderers reorg --- client/scss/pages/_new.scss | 2 +- client/themes/default/components/app.vue | 58 +++++++++++-- server/controllers/common.js | 5 +- server/core/kernel.js | 1 + server/db/migrations/2.0.0.js | 9 +- server/jobs/render-page.js | 2 + server/models/pages.js | 2 +- .../renderer/html-asciinema/definition.yml | 7 ++ .../renderer/html-asciinema/renderer.js | 1 + .../renderer/html-blockquotes/definition.yml | 7 ++ .../renderer/html-blockquotes/renderer.js | 1 + .../renderer/html-mathjax/definition.yml | 7 ++ .../{common => html-mathjax}/mathjax.js | 0 .../renderer/html-mediaplayers/definition.yml | 7 ++ .../renderer/html-mediaplayers/renderer.js | 1 + .../renderer/html-security/definition.yml | 7 ++ .../renderer/html-security/renderer.js | 1 + .../renderer/markdown-abbr/definition.yml | 7 ++ .../renderer.js} | 0 .../renderer/markdown-core/definition.yml | 29 +++++++ .../renderer/markdown-core/renderer.js | 1 + .../renderer/markdown-emoji/definition.yml | 7 ++ .../emoji.js => markdown-emoji/renderer.js} | 0 .../markdown-expandtabs/definition.yml | 7 ++ .../renderer.js} | 0 .../markdown-footnotes/definition.yml | 7 ++ .../renderer.js} | 0 .../renderer/markdown-mathjax/definition.yml | 7 ++ .../renderer.js} | 0 .../renderer/markdown-mermaid/definition.yml | 7 ++ .../renderer/markdown-mermaid/renderer.js | 1 + .../renderer/markdown-plantuml/definition.yml | 7 ++ .../renderer/markdown-plantuml/renderer.js | 1 + .../markdown-tasklists/definition.yml | 7 ++ .../renderer.js} | 0 server/views/page.pug | 87 +++++++++++-------- 36 files changed, 241 insertions(+), 52 deletions(-) create mode 100644 server/modules/renderer/html-asciinema/definition.yml create mode 100644 server/modules/renderer/html-asciinema/renderer.js create mode 100644 server/modules/renderer/html-blockquotes/definition.yml create mode 100644 server/modules/renderer/html-blockquotes/renderer.js create mode 100644 server/modules/renderer/html-mathjax/definition.yml rename server/modules/renderer/{common => html-mathjax}/mathjax.js (100%) create mode 100644 server/modules/renderer/html-mediaplayers/definition.yml create mode 100644 server/modules/renderer/html-mediaplayers/renderer.js create mode 100644 server/modules/renderer/html-security/definition.yml create mode 100644 server/modules/renderer/html-security/renderer.js create mode 100644 server/modules/renderer/markdown-abbr/definition.yml rename server/modules/renderer/{markdown/abbreviations.js => markdown-abbr/renderer.js} (100%) create mode 100644 server/modules/renderer/markdown-core/definition.yml create mode 100644 server/modules/renderer/markdown-core/renderer.js create mode 100644 server/modules/renderer/markdown-emoji/definition.yml rename server/modules/renderer/{markdown/emoji.js => markdown-emoji/renderer.js} (100%) create mode 100644 server/modules/renderer/markdown-expandtabs/definition.yml rename server/modules/renderer/{markdown/expand-tabs.js => markdown-expandtabs/renderer.js} (100%) create mode 100644 server/modules/renderer/markdown-footnotes/definition.yml rename server/modules/renderer/{markdown/footnotes.js => markdown-footnotes/renderer.js} (100%) create mode 100644 server/modules/renderer/markdown-mathjax/definition.yml rename server/modules/renderer/{markdown/mathjax.js => markdown-mathjax/renderer.js} (100%) create mode 100644 server/modules/renderer/markdown-mermaid/definition.yml create mode 100644 server/modules/renderer/markdown-mermaid/renderer.js create mode 100644 server/modules/renderer/markdown-plantuml/definition.yml create mode 100644 server/modules/renderer/markdown-plantuml/renderer.js create mode 100644 server/modules/renderer/markdown-tasklists/definition.yml rename server/modules/renderer/{markdown/tasks-lists.js => markdown-tasklists/renderer.js} (100%) diff --git a/client/scss/pages/_new.scss b/client/scss/pages/_new.scss index 81cc16aa..630209f0 100644 --- a/client/scss/pages/_new.scss +++ b/client/scss/pages/_new.scss @@ -59,7 +59,7 @@ height: 250px; margin-bottom: 3rem; z-index: 2; - animation-duration: 3s; + animation-duration: 2s; @include until($tablet) { height: 200px; diff --git a/client/themes/default/components/app.vue b/client/themes/default/components/app.vue index ce9b9aad..2dd77188 100644 --- a/client/themes/default/components/app.vue +++ b/client/themes/default/components/app.vue @@ -37,8 +37,10 @@ v-breadcrumbs-item Galaxy v-breadcrumbs-item Solar System v-breadcrumbs-item Planet Earth - v-spacer - status-indicator(active, pulse) + template(v-if='!isPublished') + v-spacer + .caption.red--text Unpublished + status-indicator.ml-3(negative, pulse) v-divider v-layout(row) v-flex(xs12, lg9, xl10) @@ -53,11 +55,11 @@ v-toolbar(color='grey lighten-4', flat, :height='90') div .caption.grey--text.text--lighten-1 Last edited by - .body-2.grey--text.text--darken-3 John Doe - .caption.grey--text.text--darken-1 Monday at 12:34 PM + .body-2.grey--text.text--darken-3 {{ authorName }} + .caption.grey--text.text--darken-1 {{ updatedAt | moment('calendar') }} v-spacer - v-tooltip(bottom) - v-btn(icon, slot='activator') + v-tooltip(left) + v-btn(icon, slot='activator', :href='"/e/" + path') v-icon(color='grey') edit span Edit Page v-divider @@ -81,9 +83,15 @@ v-divider v-toolbar(color='grey lighten-3', flat, dense) v-spacer - v-btn(icon): v-icon(color='grey') bookmark - v-btn(icon): v-icon(color='grey') share - v-btn(icon): v-icon(color='grey') print + v-tooltip(bottom) + v-btn(icon, slot='activator'): v-icon(color='grey') bookmark + span Bookmark + v-tooltip(bottom) + v-btn(icon, slot='activator'): v-icon(color='grey') share + span Share + v-tooltip(bottom) + v-btn(icon, slot='activator'): v-icon(color='grey') print + span Print Format v-spacer nav-footer @@ -96,6 +104,14 @@ export default { StatusIndicator }, props: { + locale: { + type: String, + default: 'en' + }, + path: { + type: String, + default: 'home' + }, title: { type: String, default: 'Untitled Page' @@ -103,6 +119,30 @@ export default { description: { type: String, default: '' + }, + createdAt: { + type: String, + default: '' + }, + updatedAt: { + type: String, + default: '' + }, + tags: { + type: Array, + default: () => ([]) + }, + authorName: { + type: String, + default: 'Unknown' + }, + authorId: { + type: Number, + default: 0 + }, + isPublished: { + type: Boolean, + default: false } }, data() { diff --git a/server/controllers/common.js b/server/controllers/common.js index 29ed2187..02ef965d 100644 --- a/server/controllers/common.js +++ b/server/controllers/common.js @@ -33,10 +33,11 @@ router.get('/*', async (req, res, next) => { const page = await WIKI.models.pages.getPage({ path: pageArgs.path, locale: pageArgs.locale, - userId: req.user.id + userId: req.user.id, + private: false }) if (page) { - res.render('page') + res.render('page', { page }) } else if (pageArgs.path === 'home') { res.render('welcome') } else { diff --git a/server/core/kernel.js b/server/core/kernel.js index e3d55a42..3c389c52 100644 --- a/server/core/kernel.js +++ b/server/core/kernel.js @@ -50,6 +50,7 @@ module.exports = { */ async postBootMaster() { await WIKI.models.authentication.refreshStrategiesFromDisk() + await WIKI.models.editors.refreshEditorsFromDisk() await WIKI.models.storage.refreshTargetsFromDisk() await WIKI.auth.activateStrategies() diff --git a/server/db/migrations/2.0.0.js b/server/db/migrations/2.0.0.js index 27aad108..380e7e48 100644 --- a/server/db/migrations/2.0.0.js +++ b/server/db/migrations/2.0.0.js @@ -96,6 +96,13 @@ exports.up = knex => { table.string('createdAt').notNullable() table.string('updatedAt').notNullable() }) + // STORAGE ----------------------------- + .createTable('renderers', table => { + table.increments('id').primary() + table.string('key').notNullable().unique() + table.boolean('isEnabled').notNullable().defaultTo(false) + table.json('config') + }) // SETTINGS ---------------------------- .createTable('settings', table => { table.increments('id').primary() @@ -108,7 +115,7 @@ exports.up = knex => { table.increments('id').primary() table.string('key').notNullable().unique() table.boolean('isEnabled').notNullable().defaultTo(false) - table.enum('mode', ['sync', 'push', 'pull']).notNullable().defaultTo('push') + table.string('mode', ['sync', 'push', 'pull']).notNullable().defaultTo('push') table.json('config') }) // TAGS -------------------------------- diff --git a/server/jobs/render-page.js b/server/jobs/render-page.js index 528ea35e..a8df0cd2 100644 --- a/server/jobs/render-page.js +++ b/server/jobs/render-page.js @@ -2,6 +2,8 @@ require('../core/worker') /* global WIKI */ +WIKI.models = require('../core/db').init() + module.exports = async (job) => { WIKI.logger.info(`Rendering page ${job.data.path}...`) diff --git a/server/models/pages.js b/server/models/pages.js index d8959f2d..6f2de09a 100644 --- a/server/models/pages.js +++ b/server/models/pages.js @@ -116,7 +116,7 @@ module.exports = class Page extends Model { authorId: opts.authorId, content: opts.content, creatorId: opts.authorId, - contentType: _.get(WIKI.data.editors, `${opts.editor}.contentType`, 'text'), + contentType: _.get(_.find(WIKI.data.editors, ['key', opts.editor]), `contentType`, 'text'), description: opts.description, editorKey: opts.editor, isPrivate: opts.isPrivate, diff --git a/server/modules/renderer/html-asciinema/definition.yml b/server/modules/renderer/html-asciinema/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/html-asciinema/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/html-asciinema/renderer.js b/server/modules/renderer/html-asciinema/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/html-asciinema/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/html-blockquotes/definition.yml b/server/modules/renderer/html-blockquotes/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/html-blockquotes/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/html-blockquotes/renderer.js b/server/modules/renderer/html-blockquotes/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/html-blockquotes/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/html-mathjax/definition.yml b/server/modules/renderer/html-mathjax/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/html-mathjax/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/common/mathjax.js b/server/modules/renderer/html-mathjax/mathjax.js similarity index 100% rename from server/modules/renderer/common/mathjax.js rename to server/modules/renderer/html-mathjax/mathjax.js diff --git a/server/modules/renderer/html-mediaplayers/definition.yml b/server/modules/renderer/html-mediaplayers/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/html-mediaplayers/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/html-mediaplayers/renderer.js b/server/modules/renderer/html-mediaplayers/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/html-mediaplayers/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/html-security/definition.yml b/server/modules/renderer/html-security/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/html-security/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/html-security/renderer.js b/server/modules/renderer/html-security/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/html-security/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/markdown-abbr/definition.yml b/server/modules/renderer/markdown-abbr/definition.yml new file mode 100644 index 00000000..0454c0ea --- /dev/null +++ b/server/modules/renderer/markdown-abbr/definition.yml @@ -0,0 +1,7 @@ +key: markdownAbbr +title: Abbreviations +description: Parse abbreviations into abbr tags +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/abbreviations.js b/server/modules/renderer/markdown-abbr/renderer.js similarity index 100% rename from server/modules/renderer/markdown/abbreviations.js rename to server/modules/renderer/markdown-abbr/renderer.js diff --git a/server/modules/renderer/markdown-core/definition.yml b/server/modules/renderer/markdown-core/definition.yml new file mode 100644 index 00000000..6c2cb483 --- /dev/null +++ b/server/modules/renderer/markdown-core/definition.yml @@ -0,0 +1,29 @@ +key: markdownCore +title: Core +description: Basic Markdown Parser +author: requarks.io +dependsOn: [] +props: + linkify: + type: Boolean + default: true + title: Automatically convert links + hint: Links will automatically be converted to clickable links. + linebreaks: + type: Boolean + default: true + title: Automatically convert line breaks + hint: Add linebreaks within paragraphs. + highlightCode: + type: Boolean + default: true + title: Highlight code blocks + hint: Add syntax coloring to code blocks. + codeTheme: + type: String + default: light + title: Code Color Theme + hint: Color theme for code blocks + enum: + - light + - dark diff --git a/server/modules/renderer/markdown-core/renderer.js b/server/modules/renderer/markdown-core/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/markdown-core/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/markdown-emoji/definition.yml b/server/modules/renderer/markdown-emoji/definition.yml new file mode 100644 index 00000000..3220194b --- /dev/null +++ b/server/modules/renderer/markdown-emoji/definition.yml @@ -0,0 +1,7 @@ +key: markdownEmoji +title: Emoji +description: Convert tags to emojis +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/emoji.js b/server/modules/renderer/markdown-emoji/renderer.js similarity index 100% rename from server/modules/renderer/markdown/emoji.js rename to server/modules/renderer/markdown-emoji/renderer.js diff --git a/server/modules/renderer/markdown-expandtabs/definition.yml b/server/modules/renderer/markdown-expandtabs/definition.yml new file mode 100644 index 00000000..92f7cada --- /dev/null +++ b/server/modules/renderer/markdown-expandtabs/definition.yml @@ -0,0 +1,7 @@ +key: markdownExpandtabs +title: Expand Tabs +description: Replace tabs with spaces in code blocks +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/expand-tabs.js b/server/modules/renderer/markdown-expandtabs/renderer.js similarity index 100% rename from server/modules/renderer/markdown/expand-tabs.js rename to server/modules/renderer/markdown-expandtabs/renderer.js diff --git a/server/modules/renderer/markdown-footnotes/definition.yml b/server/modules/renderer/markdown-footnotes/definition.yml new file mode 100644 index 00000000..44913865 --- /dev/null +++ b/server/modules/renderer/markdown-footnotes/definition.yml @@ -0,0 +1,7 @@ +key: markdownFootnotes +title: Footnotes +description: Parse footnotes references +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/footnotes.js b/server/modules/renderer/markdown-footnotes/renderer.js similarity index 100% rename from server/modules/renderer/markdown/footnotes.js rename to server/modules/renderer/markdown-footnotes/renderer.js diff --git a/server/modules/renderer/markdown-mathjax/definition.yml b/server/modules/renderer/markdown-mathjax/definition.yml new file mode 100644 index 00000000..dd7b1c84 --- /dev/null +++ b/server/modules/renderer/markdown-mathjax/definition.yml @@ -0,0 +1,7 @@ +key: markdownMathjax +title: Mathjax Pre-Processor +description: Pre-parse TeX blocks for Mathjax +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/mathjax.js b/server/modules/renderer/markdown-mathjax/renderer.js similarity index 100% rename from server/modules/renderer/markdown/mathjax.js rename to server/modules/renderer/markdown-mathjax/renderer.js diff --git a/server/modules/renderer/markdown-mermaid/definition.yml b/server/modules/renderer/markdown-mermaid/definition.yml new file mode 100644 index 00000000..573e6e96 --- /dev/null +++ b/server/modules/renderer/markdown-mermaid/definition.yml @@ -0,0 +1,7 @@ +key: markdownMermaid +title: Mermaid +description: Generate flowcharts from Mermaid syntax +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown-mermaid/renderer.js b/server/modules/renderer/markdown-mermaid/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/markdown-mermaid/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/markdown-plantuml/definition.yml b/server/modules/renderer/markdown-plantuml/definition.yml new file mode 100644 index 00000000..0a24302d --- /dev/null +++ b/server/modules/renderer/markdown-plantuml/definition.yml @@ -0,0 +1,7 @@ +key: markdownPlantuml +title: PlantUML +description: Generate diagrams from PlantUML syntax +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown-plantuml/renderer.js b/server/modules/renderer/markdown-plantuml/renderer.js new file mode 100644 index 00000000..4ba52ba2 --- /dev/null +++ b/server/modules/renderer/markdown-plantuml/renderer.js @@ -0,0 +1 @@ +module.exports = {} diff --git a/server/modules/renderer/markdown-tasklists/definition.yml b/server/modules/renderer/markdown-tasklists/definition.yml new file mode 100644 index 00000000..27c5410f --- /dev/null +++ b/server/modules/renderer/markdown-tasklists/definition.yml @@ -0,0 +1,7 @@ +key: markdownTasklists +title: Task Lists +description: Parse task lists to checkboxes +author: requarks.io +dependsOn: + - markdownCore +props: {} diff --git a/server/modules/renderer/markdown/tasks-lists.js b/server/modules/renderer/markdown-tasklists/renderer.js similarity index 100% rename from server/modules/renderer/markdown/tasks-lists.js rename to server/modules/renderer/markdown-tasklists/renderer.js diff --git a/server/views/page.pug b/server/views/page.pug index 95c59111..1aa2b854 100644 --- a/server/views/page.pug +++ b/server/views/page.pug @@ -4,42 +4,53 @@ block head block body #root - page(title='Planet Earth', description='The 3rd planet of the solar system') - template(slot='contents') - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - h1 Introduction - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - h1 Cities - h2 New York - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - h2 Chicago - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. - p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] - p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. - p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. - p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + page( + locale=page.localeCode + path=page.path + title=page.title + description=page.description + tags=page.tags + created-at=page.createdAt + updated-at=page.updatedAt + author-name=page.authorName + author-id=page.authorId + is-published=page.isPublished + ) + template(slot='contents')!= page.render + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- h1 Introduction + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- h1 Cities + //- h2 New York + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- h2 Chicago + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states. + //- p Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago.[24][25][26] Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.[n 5] + //- p Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth.[27] The gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest of the four terrestrial planets. + //- p Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water, mostly by oceans.[29] The remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, and a convecting mantle that drives plate tectonics. + //- p Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms. Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive.[30][31] In the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species[32] that ever lived on Earth are extinct.[33][34] Estimates of the number of species on Earth today vary widely;[35][36][37] most species have not been described.[38] Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.[39] Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states.