{"id":179,"date":"2022-02-07T23:11:13","date_gmt":"2022-02-07T23:11:13","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/astronomy\/?post_type=chapter&#038;p=179"},"modified":"2022-02-11T18:14:37","modified_gmt":"2022-02-11T18:14:37","slug":"3-4-orbits-in-the-solar-system","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/astronomy\/chapter\/3-4-orbits-in-the-solar-system\/","title":{"raw":"3.4 Orbits in the Solar System","rendered":"3.4 Orbits in the Solar System"},"content":{"raw":"<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Learning Objectives<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<p id=\"fs-id1168979569927\" class=\" \">By the end of this section, you will be able to:<\/p>\r\n\r\n<ul id=\"fs-id1163975429192\">\r\n \t<li>Compare the orbital characteristics of the planets in the solar system<\/li>\r\n \t<li>Compare the orbital characteristics of asteroids and comets in the solar system<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<p id=\"fs-id1163975551490\" class=\" \">Recall that the path of an object under the influence of gravity through space is called its orbit, whether that object is a spacecraft, planet, star, or galaxy. An orbit, once determined, allows the future positions of the object to be calculated.<\/p>\r\n<p id=\"fs-id1163975548187\" class=\" \">Two points in any orbit in our solar system have been given special names. The place where the planet is closest to the Sun (<em data-effect=\"italics\">helios<\/em>\u00a0in Greek) and moves the fastest is called the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term106\" data-type=\"term\">perihelion<\/span>\u00a0of its orbit, and the place where it is farthest away and moves the most slowly is the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term107\" data-type=\"term\">aphelion<\/span>. For the Moon or a satellite orbiting Earth (<em data-effect=\"italics\">gee<\/em>\u00a0in Greek), the corresponding terms are\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term108\" data-type=\"term\">perigee<\/span>\u00a0and\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term109\" data-type=\"term\">apogee<\/span>. (In this book, we use the word\u00a0<em data-effect=\"italics\">moon<\/em>\u00a0for a natural object that goes around a planet and the word\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term110\" data-type=\"term\">satellite<\/span>\u00a0to mean a human-made object that revolves around a planet.)<\/p>\r\n\r\n<section id=\"fs-id1163975557819\" data-depth=\"1\">\r\n<h3 data-type=\"title\">Orbits of the Planets<\/h3>\r\n<p id=\"fs-id1163975369497\" class=\" \">Today, Newton\u2019s work enables us to calculate and predict the orbits of the planets with marvelous precision. We know eight planets, beginning with Mercury closest to the Sun and extending outward to Neptune. The average orbital data for the planets are summarized in\u00a0Table 3.2. (Ceres is the largest of the\u00a0<em data-effect=\"italics\">asteroids,<\/em>\u00a0now considered a dwarf planet.)<\/p>\r\n<p id=\"fs-id1163975365984\" class=\" \">According to Kepler\u2019s laws, Mercury must have the shortest orbital period (88 Earth-days); thus, it has the highest orbital speed, averaging 48 kilometers per second. At the opposite extreme, Neptune has a period of 165 years and an average orbital speed of just 5 kilometers per second.<\/p>\r\n<p id=\"fs-id1163975308884\" class=\" \">All the planets have orbits of rather low eccentricity. The most eccentric orbit is that of Mercury (0.21); the rest have eccentricities smaller than 0.1. It is fortunate that among the rest, Mars has an eccentricity greater than that of many of the other planets. Otherwise the pre-telescopic observations of Brahe would not have been sufficient for Kepler to deduce that its orbit had the shape of an ellipse rather than a circle.<\/p>\r\n<p id=\"fs-id1163975578893\" class=\" \">The planetary orbits are also confined close to a common plane, which is near the plane of Earth\u2019s orbit (called the ecliptic). The strange orbit of the dwarf planet Pluto is inclined about 17\u00b0 to the ecliptic, and that of the dwarf planet Eris (orbiting even farther away from the Sun than Pluto) by 44\u00b0, but all the major planets lie within 10\u00b0 of the common plane of the solar system.<\/p>\r\n\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<h3 class=\"textbox__title\">Link to Learning<\/h3>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nJavaLab\u2019s\u00a0<a href=\"https:\/\/openstax.org\/l\/30solarsim\" target=\"_blank\" rel=\"noopener nofollow noreferrer\">solar system simulator<\/a>\u00a0allows you to explore the size and speed of the planets\u2019 orbits, and view the orbits from different perspectives.\r\n\r\n<\/div>\r\n<\/div>\r\n<h3 data-type=\"title\">Orbits of Asteroids and Comets<\/h3>\r\n<p id=\"fs-id1163975464516\" class=\" \">In addition to the eight planets, there are many smaller objects in the solar system. Some of these are moons (natural satellites) that orbit all the planets except Mercury and Venus. In addition, there are two classes of smaller objects in heliocentric orbits:\u00a0<em data-effect=\"italics\">asteroids<\/em>\u00a0and\u00a0<em data-effect=\"italics\">comets<\/em>. Both asteroids and comets are believed to be small chunks of material left over from the formation process of the solar system.<\/p>\r\n<p id=\"fs-id1163975373682\" class=\" \">In general, asteroids have orbits with smaller semimajor axes than do comets (Figure 3.10). The majority of them lie between 2.2 and 3.3 AU, in the region known as the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term111\" data-type=\"term\">asteroid belt<\/span>\u00a0(see\u00a0<a href=\"https:\/\/openstax.org\/books\/astronomy\/pages\/13-thinking-ahead#page_46f47a00-a325-4985-a7e2-92ac70b2483a\" data-page-slug=\"13-thinking-ahead\" data-page-uuid=\"46f47a00-a325-4985-a7e2-92ac70b2483a\" data-page-fragment=\"page_46f47a00-a325-4985-a7e2-92ac70b2483a\">Comets and Asteroids: Debris of the Solar System<\/a>). As you can see in\u00a0Table 3.2, the asteroid belt (represented by its largest member, Ceres) is in the middle of a gap between the orbits of Mars and Jupiter. It is because these two planets are so far apart that stable orbits of small bodies can exist in the region between them.<\/p>\r\n\r\n<div id=\"OSC_Astro_03_04_Solar\" class=\"os-figure\">\r\n<figure data-id=\"OSC_Astro_03_04_Solar\">\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"702\"]<img id=\"2\" src=\"https:\/\/openstax.org\/apps\/archive\/20210823.155019\/resources\/b735e3b52775c4e735bceec6456817b0917fd33b\" alt=\"Solar System Orbits. At the center of this illustration is the Sun, with the orbits of the inner planets drawn as black circles. The elliptical orbits of the comets Halley, Kopff, and Encke are shown in red. Encke\u2019s orbit extends across the orbits of Mercury, Venus, Earth and Mars, while the orbits of Kopff and Halley extend beyond the orbit of Jupiter. The circular orbits of the asteroids Ceres, Pallas, Vesta, and Hygeia are shown in blue, and fall mostly between the orbits of Earth and Jupiter.\" width=\"702\" height=\"686\" data-media-type=\"image\/jpeg\" \/> <strong>Figure\u00a03.10<\/strong> Solar System Orbits.\u00a0We see the orbits of typical comets and asteroids compared with those of the planets Mercury, Venus, Earth, Mars, and Jupiter (black circles). Shown in red are three comets: Halley, Kopff, and Encke. In blue are the four largest asteroids:\u00a0Ceres, Pallas,\u00a0Vesta, and Hygeia.[\/caption]<\/figure>\r\n<\/div>\r\n<div class=\"os-table os-top-titled-container\">\r\n<table id=\"fs-id1163975563522\" class=\"grid landscape aligncenter\" summary=\"Table 3.2 \"><caption>Table 3.2 Orbital Data for the Planets<\/caption>\r\n<thead>\r\n<tr valign=\"top\">\r\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Planet<\/th>\r\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Semimajor Axis (AU)<\/th>\r\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Period (y)<\/th>\r\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Eccentricity<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term114\" class=\"no-emphasis\" data-type=\"term\">Mercury<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.39<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.24<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.21<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term115\" class=\"no-emphasis\" data-type=\"term\">Venus<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.72<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.6<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.01<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term116\" class=\"no-emphasis\" data-type=\"term\">Earth<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">1<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">1.00<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.02<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term117\" class=\"no-emphasis\" data-type=\"term\">Mars<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">1.52<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">1.88<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.09<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\">(<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term118\" class=\"no-emphasis\" data-type=\"term\">Ceres<\/span>)<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">2.77<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">4.6<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.08<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term119\" class=\"no-emphasis\" data-type=\"term\">Jupiter<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">5.20<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">11.86<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.05<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term120\" class=\"no-emphasis\" data-type=\"term\">Saturn<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">9.54<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">29.46<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.06<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term121\" class=\"no-emphasis\" data-type=\"term\">Uranus<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">19.19<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">84.01<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.05<\/td>\r\n<\/tr>\r\n<tr valign=\"top\">\r\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term122\" class=\"no-emphasis\" data-type=\"term\">Neptune<\/span><\/td>\r\n<td data-valign=\"top\" data-align=\"left\">30.06<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">164.82<\/td>\r\n<td data-valign=\"top\" data-align=\"left\">0.01<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<div class=\"os-caption-container\" style=\"text-align: left;\"><span style=\"orphans: 1; text-align: initial; font-size: 1em;\">Comets generally have orbits of larger size and greater eccentricity than those of the asteroids. Typically, the eccentricity of their orbits is 0.8 or higher. According to Kepler\u2019s second law, therefore, they spend most of their time far from the Sun, moving very slowly. As they approach perihelion, the comets speed up and whip through the inner parts of their orbits more rapidly.<\/span><\/div>\r\n<\/div>\r\n<div>\r\n<div class=\"textbox\">This book was adapted from the following: Fraknoi, A., Morrison, D., &amp; Wolff, S. C. (2016). 3.4 Orbits in the Solar System. In <i>Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/3-4-orbits-in-the-solar-system under a <a href=\"http:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">Creative Commons Attribution License 4.0<\/a><\/div>\r\n<div>Access the entire book for free at <a href=\"https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction\">https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>\r\n<\/div>\r\n<\/section>","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Learning Objectives<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p id=\"fs-id1168979569927\" class=\"\">By the end of this section, you will be able to:<\/p>\n<ul id=\"fs-id1163975429192\">\n<li>Compare the orbital characteristics of the planets in the solar system<\/li>\n<li>Compare the orbital characteristics of asteroids and comets in the solar system<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p id=\"fs-id1163975551490\" class=\"\">Recall that the path of an object under the influence of gravity through space is called its orbit, whether that object is a spacecraft, planet, star, or galaxy. An orbit, once determined, allows the future positions of the object to be calculated.<\/p>\n<p id=\"fs-id1163975548187\" class=\"\">Two points in any orbit in our solar system have been given special names. The place where the planet is closest to the Sun (<em data-effect=\"italics\">helios<\/em>\u00a0in Greek) and moves the fastest is called the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term106\" data-type=\"term\">perihelion<\/span>\u00a0of its orbit, and the place where it is farthest away and moves the most slowly is the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term107\" data-type=\"term\">aphelion<\/span>. For the Moon or a satellite orbiting Earth (<em data-effect=\"italics\">gee<\/em>\u00a0in Greek), the corresponding terms are\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term108\" data-type=\"term\">perigee<\/span>\u00a0and\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term109\" data-type=\"term\">apogee<\/span>. (In this book, we use the word\u00a0<em data-effect=\"italics\">moon<\/em>\u00a0for a natural object that goes around a planet and the word\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term110\" data-type=\"term\">satellite<\/span>\u00a0to mean a human-made object that revolves around a planet.)<\/p>\n<section id=\"fs-id1163975557819\" data-depth=\"1\">\n<h3 data-type=\"title\">Orbits of the Planets<\/h3>\n<p id=\"fs-id1163975369497\" class=\"\">Today, Newton\u2019s work enables us to calculate and predict the orbits of the planets with marvelous precision. We know eight planets, beginning with Mercury closest to the Sun and extending outward to Neptune. The average orbital data for the planets are summarized in\u00a0Table 3.2. (Ceres is the largest of the\u00a0<em data-effect=\"italics\">asteroids,<\/em>\u00a0now considered a dwarf planet.)<\/p>\n<p id=\"fs-id1163975365984\" class=\"\">According to Kepler\u2019s laws, Mercury must have the shortest orbital period (88 Earth-days); thus, it has the highest orbital speed, averaging 48 kilometers per second. At the opposite extreme, Neptune has a period of 165 years and an average orbital speed of just 5 kilometers per second.<\/p>\n<p id=\"fs-id1163975308884\" class=\"\">All the planets have orbits of rather low eccentricity. The most eccentric orbit is that of Mercury (0.21); the rest have eccentricities smaller than 0.1. It is fortunate that among the rest, Mars has an eccentricity greater than that of many of the other planets. Otherwise the pre-telescopic observations of Brahe would not have been sufficient for Kepler to deduce that its orbit had the shape of an ellipse rather than a circle.<\/p>\n<p id=\"fs-id1163975578893\" class=\"\">The planetary orbits are also confined close to a common plane, which is near the plane of Earth\u2019s orbit (called the ecliptic). The strange orbit of the dwarf planet Pluto is inclined about 17\u00b0 to the ecliptic, and that of the dwarf planet Eris (orbiting even farther away from the Sun than Pluto) by 44\u00b0, but all the major planets lie within 10\u00b0 of the common plane of the solar system.<\/p>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h3 class=\"textbox__title\">Link to Learning<\/h3>\n<\/header>\n<div class=\"textbox__content\">\n<p>JavaLab\u2019s\u00a0<a href=\"https:\/\/openstax.org\/l\/30solarsim\" target=\"_blank\" rel=\"noopener nofollow noreferrer\">solar system simulator<\/a>\u00a0allows you to explore the size and speed of the planets\u2019 orbits, and view the orbits from different perspectives.<\/p>\n<\/div>\n<\/div>\n<h3 data-type=\"title\">Orbits of Asteroids and Comets<\/h3>\n<p id=\"fs-id1163975464516\" class=\"\">In addition to the eight planets, there are many smaller objects in the solar system. Some of these are moons (natural satellites) that orbit all the planets except Mercury and Venus. In addition, there are two classes of smaller objects in heliocentric orbits:\u00a0<em data-effect=\"italics\">asteroids<\/em>\u00a0and\u00a0<em data-effect=\"italics\">comets<\/em>. Both asteroids and comets are believed to be small chunks of material left over from the formation process of the solar system.<\/p>\n<p id=\"fs-id1163975373682\" class=\"\">In general, asteroids have orbits with smaller semimajor axes than do comets (Figure 3.10). The majority of them lie between 2.2 and 3.3 AU, in the region known as the\u00a0<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term111\" data-type=\"term\">asteroid belt<\/span>\u00a0(see\u00a0<a href=\"https:\/\/openstax.org\/books\/astronomy\/pages\/13-thinking-ahead#page_46f47a00-a325-4985-a7e2-92ac70b2483a\" data-page-slug=\"13-thinking-ahead\" data-page-uuid=\"46f47a00-a325-4985-a7e2-92ac70b2483a\" data-page-fragment=\"page_46f47a00-a325-4985-a7e2-92ac70b2483a\">Comets and Asteroids: Debris of the Solar System<\/a>). As you can see in\u00a0Table 3.2, the asteroid belt (represented by its largest member, Ceres) is in the middle of a gap between the orbits of Mars and Jupiter. It is because these two planets are so far apart that stable orbits of small bodies can exist in the region between them.<\/p>\n<div id=\"OSC_Astro_03_04_Solar\" class=\"os-figure\">\n<figure data-id=\"OSC_Astro_03_04_Solar\">\n<figure style=\"width: 702px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" id=\"2\" src=\"https:\/\/openstax.org\/apps\/archive\/20210823.155019\/resources\/b735e3b52775c4e735bceec6456817b0917fd33b\" alt=\"Solar System Orbits. At the center of this illustration is the Sun, with the orbits of the inner planets drawn as black circles. The elliptical orbits of the comets Halley, Kopff, and Encke are shown in red. Encke\u2019s orbit extends across the orbits of Mercury, Venus, Earth and Mars, while the orbits of Kopff and Halley extend beyond the orbit of Jupiter. The circular orbits of the asteroids Ceres, Pallas, Vesta, and Hygeia are shown in blue, and fall mostly between the orbits of Earth and Jupiter.\" width=\"702\" height=\"686\" data-media-type=\"image\/jpeg\" \/><figcaption class=\"wp-caption-text\"><strong>Figure\u00a03.10<\/strong> Solar System Orbits.\u00a0We see the orbits of typical comets and asteroids compared with those of the planets Mercury, Venus, Earth, Mars, and Jupiter (black circles). Shown in red are three comets: Halley, Kopff, and Encke. In blue are the four largest asteroids:\u00a0Ceres, Pallas,\u00a0Vesta, and Hygeia.<\/figcaption><\/figure>\n<\/figure>\n<\/div>\n<div class=\"os-table os-top-titled-container\">\n<table id=\"fs-id1163975563522\" class=\"grid landscape aligncenter\" summary=\"Table 3.2\">\n<caption>Table 3.2 Orbital Data for the Planets<\/caption>\n<thead>\n<tr valign=\"top\">\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Planet<\/th>\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Semimajor Axis (AU)<\/th>\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Period (y)<\/th>\n<th scope=\"col\" data-valign=\"top\" data-align=\"center\">Eccentricity<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term114\" class=\"no-emphasis\" data-type=\"term\">Mercury<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">0.39<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.24<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.21<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term115\" class=\"no-emphasis\" data-type=\"term\">Venus<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">0.72<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.6<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.01<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term116\" class=\"no-emphasis\" data-type=\"term\">Earth<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">1<\/td>\n<td data-valign=\"top\" data-align=\"left\">1.00<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.02<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term117\" class=\"no-emphasis\" data-type=\"term\">Mars<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">1.52<\/td>\n<td data-valign=\"top\" data-align=\"left\">1.88<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.09<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\">(<span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term118\" class=\"no-emphasis\" data-type=\"term\">Ceres<\/span>)<\/td>\n<td data-valign=\"top\" data-align=\"left\">2.77<\/td>\n<td data-valign=\"top\" data-align=\"left\">4.6<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.08<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term119\" class=\"no-emphasis\" data-type=\"term\">Jupiter<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">5.20<\/td>\n<td data-valign=\"top\" data-align=\"left\">11.86<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.05<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term120\" class=\"no-emphasis\" data-type=\"term\">Saturn<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">9.54<\/td>\n<td data-valign=\"top\" data-align=\"left\">29.46<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.06<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term121\" class=\"no-emphasis\" data-type=\"term\">Uranus<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">19.19<\/td>\n<td data-valign=\"top\" data-align=\"left\">84.01<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.05<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td data-valign=\"top\" data-align=\"left\"><span id=\"e2c6b1d7-f6ec-4586-9648-770769fb9b34_term122\" class=\"no-emphasis\" data-type=\"term\">Neptune<\/span><\/td>\n<td data-valign=\"top\" data-align=\"left\">30.06<\/td>\n<td data-valign=\"top\" data-align=\"left\">164.82<\/td>\n<td data-valign=\"top\" data-align=\"left\">0.01<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"os-caption-container\" style=\"text-align: left;\"><span style=\"orphans: 1; text-align: initial; font-size: 1em;\">Comets generally have orbits of larger size and greater eccentricity than those of the asteroids. Typically, the eccentricity of their orbits is 0.8 or higher. According to Kepler\u2019s second law, therefore, they spend most of their time far from the Sun, moving very slowly. As they approach perihelion, the comets speed up and whip through the inner parts of their orbits more rapidly.<\/span><\/div>\n<\/div>\n<div>\n<div class=\"textbox\">This book was adapted from the following: Fraknoi, A., Morrison, D., &amp; Wolff, S. C. (2016). 3.4 Orbits in the Solar System. In <i>Astronomy<\/i>. OpenStax. https:\/\/openstax.org\/books\/astronomy\/pages\/3-4-orbits-in-the-solar-system under a <a href=\"http:\/\/creativecommons.org\/licenses\/by\/4.0\/\" target=\"_blank\" rel=\"noopener noreferrer\">Creative Commons Attribution License 4.0<\/a><\/div>\n<div>Access the entire book for free at <a href=\"https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction\">https:\/\/openstax.org\/books\/astronomy\/pages\/1-introduction<\/a><\/div>\n<\/div>\n<\/section>\n","protected":false},"author":33,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-179","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":148,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/179","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/users\/33"}],"version-history":[{"count":2,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/179\/revisions"}],"predecessor-version":[{"id":213,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/179\/revisions\/213"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/parts\/148"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapters\/179\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/media?parent=179"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/pressbooks\/v2\/chapter-type?post=179"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/contributor?post=179"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/astronomy\/wp-json\/wp\/v2\/license?post=179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}