page_title: Jupiter
section_title: Mass and size
hierarchical_section_title: Jupiter / Physical characteristics / Mass and size
caption_attribution_description: English: This image has four quadrants showing relative sizes of four key Solar System objects: the Sun, Jupiter, Earth and the Moon. On the top-left, all four are shown together with sizes to scale. On the top-right, Jupiter is shown to have a diameter ten times smaller (0.10045×) than the diameter of the Sun. On the bottom-left, Jupiter is shown to be eleven times (10.9733×) the diameter of the Earth. Finally on the bottom-right, the Earth is shown to be three and two-thirds (3.6676×) the diameter of the Moon. This is an 11/3 diameter ratio exactly (0.09% error). The image is titled "Solar System Orders of Magnitude" because of how, generally speaking, the diameter decreases by an order of magnitude when going from the central star, to the gas giants, to the terrestrial planets, down to the moon objects. The fourth image actually shows an unusual situation in the Solar System in that Earth's Moon is closer to its planet's size than other moons are to their planet's size (the Earth-Moon system could actually be considered a double planet). The string of eleven Earth diameters across Jupiter is purposely faded near the Great Red Spot in order to show how the Spot and the Earth have similar diameters. In reference to Jupiter itself, its Red Spot has a diameter that is one order of magnitude smaller than its own diameter. This can be extended to the size relationship of the Sun to Jupiter, that if there were a Giant Sunspot 1/10th of the Sun's diameter, then that Sunspot would have the same diameter as Jupiter. The reason why the bodies are diagrammed at an angle is because their equatorial diameters are larger than their polar diameters, especially for the gas giant, Jupiter. The size ratios depicted here are based upon their average diameters. Also, while it may appear that the bottom-left quadrant shows Jupiter's diameter as slightly smaller than 10.9733 Earth diameters, that is only because a sliver of a crescent of Jupiter is hidden in shadow - the lighting on this image is not 100% "full". NOTE: No effort was made to present the vast distances between any of these bodies to scale. This image was made using GIMP image editing software.
context_page_description: Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter is one of the brightest objects visible to the naked eye in the night sky, and has been known to ancient civilizations since before recorded history. It is named after the Roman god Jupiter. When viewed from Earth, Jupiter can be bright enough for its reflected light to cast visible shadows, and is on average the third-brightest natural object in the night sky after the Moon and Venus.
  Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries.
context_section_description: Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center. Jupiter is much larger than Earth and considerably less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about 1/10 the radius of the Sun, and its mass is 0.001 times the mass of the Sun, so the densities of the two bodies are similar. A "Jupiter mass" (MJ or MJup) is often used as a unit to describe masses of other objects, particularly extrasolar planets and brown dwarfs. So, for example, the extrasolar planet HD 209458 b has a mass of 0.69 MJ, while Kappa Andromedae b has a mass of 12.8 MJ.
  Theoretical models indicate that if Jupiter had much more mass than it does at present, it would shrink. For small changes in mass, the radius would not change appreciably, and above about 500 M⊕ (1.6 Jupiter masses) the interior would become so much more compressed under the increased pressure that its volume would decrease despite the increasing amount of matter. As a result, Jupiter is thought to have about as large a diameter as a planet of its composition and evolutionary history can achieve. The process of further shrinkage with increasing mass would continue until appreciable stellar ignition was achieved, as in high-mass brown dwarfs having around 50 Jupiter masses.
  Although Jupiter would need to be about 75 times as massive to fuse hydrogen and become a star, the smallest red dwarf is only about 30 percent larger in radius than Jupiter. Despite this, Jupiter still radiates more heat than it receives from the Sun; the amount of heat produced inside it is similar to the total solar radiation it receives. This additional heat is generated by the Kelvin–Helmholtz mechanism through contraction. This process causes Jupiter to shrink by about 2 cm each year. When it was first formed, Jupiter was much hotter and was about twice its current diameter.
caption: Jupiter's diameter is one order of magnitude smaller (×0.10045) than that of the Sun, and one order of magnitude larger (×10.9733) than that of Earth. The Great Red Spot is roughly the same size as Earth.
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