Comparative sizes of planets and stars
Comparative sizes of the terrestrial planets
|Automatic translation||Updated June 01, 2013|
Our Universe is really vast and empty, though a few grains of matter dotting the cosmic void, from small dust grains to the biggest stars. Between small planets in the solar system and the biggest stars, the size difference is enormous, for example, the diameter of the star Betelgeuse is 141,863 times larger than the diameter of the Earth.
Jupiter, the largest planet in the system, has captured 71% of the remainder. The other planets are shared the residue of the gravitational evolution, i.e. 0.038% of the total mass. The four terrestrial planets represent only 11.17% of the total mass of the solar system planets.
Image: Comparative sizes of 4 terrestrial planets, Mercury left, Venus, Earth and Mars. These four terrestrial planets represent only 11.17% of the total mass of the solar system planets.
Size comparison of planets with Earth
A dwarf planet, since the new definition of August 2006, is a celestial body orbiting the Sun that has sufficient mass for its self-gravity to outweigh the cohesive forces of the solid body and assumes a hydrostatic equilibrium (in a nearly spherical shape), and which is not a satellite, but does not clear up in its orbital neighborhood.
Image: Comparative sizes of trans-Neptunian objects, located in the Kuiper Belt, compared to the size of the Earth (left).
Neptune is in the outer solar system, 4.5 billion km. Neptune is four times larger than the earth.
Image: Compare the size of Neptune with the Earth. In this picture you can see the dark blue anticyclone, comparable to the Great Red Spot of Jupiter, that it is twice as large (pictured right).
Comparison of the sizes of stars
Image: Comparative sizes of some super giant stars like Antares, Betelgeuse, Rigel, Aldebaran and some white dwarfs as Arcturus, Pollux, Sirius and the Sun (left). It is thanks to the Stefan-Boltzmann law, which astronomers can easily calculate the radii of the stars (see note below). In 1879, the Austrian physicist Josef Stefan, who is interested in radiation from hot bodies, discovers that the total energy emitted by an object is proportional to the 4th power of its absolute temperature. Antares has a diameter of ≈ 700 times that of the Sun, or about 1 billion kilometers. Betelgeuse has a diameter ≈ 1300 times that of the Sun. Aldebaran has a diameter ≈ 45 times that of the Sun. Rigel has a diameter of about 116 million km, ≈ 35 times that of the Sun. Arcturus is 20 times bigger than the sun. Pollux is ≈ 8 times larger than the sun.NB: Thanks to the Stefan-Boltzmann law, astronomers can calculate the radii of the stars. The brightness of a star is: L = 4πσR2T4
L is the brightness, σ is the Stefan-Boltzmann constant, R the radius of the star and T the temperature.
Image: Size of the Earth compared to the size of a white dwarf (left). White dwarfs are stars off residues. This is the penultimate phase of the evolution of stars whose mass is between 0.3 and 1.4 times that of the Sun. The density of a white dwarf is very high. A white dwarf of about one solar mass has a radius of the order of that of the Earth.
Video on the size of planets and stars
Our Sun is very small, compared to some stars. The planets are as dust compared to blue and red Giant of our universe. This video on YouTube, the relative sizes of the planets and stars are made of the smallest to the largest.
Video: Comparative sizes of some giant and supergiant stars like Antares, Betelgeuse, Rigel, Aldebaran, Pistol star Antares A Mu Cephei, the red hypergiant VY Canis Majoris and some white dwarfs as Arcturus, Pollux, Sirius and the Sun. credit & Copyright: morn1415 (YouTube)NB: VY Canis Majoris (VY CMa) is a red star hypergiant type, which is located in the constellation Canis Major, at 5000 light years from our Sun. VY Canis Majoris is the largest known star and one of the brightest.
Apparent size of the Moon and the Sun
Distance from the Sun varies throughout the year between 147,098,074 km and 152,097,701 km, it is a function of the eccentricity of Earth's orbit and hence its apparent size as seen from Earth also varies. The distance of the Moon varies during the month between 363,104 and 405,696 km, it is a function of the eccentricity of the lunar orbit and hence its apparent size as seen from Earth also varies. When the Moon is at its apogee, that is farthest from the Earth, its apparent diameter is smaller than that of the sun at this point of its orbit is too small to completely cover the solar disk. When the Moon is at perigee, i.e. closer to the Earth, its apparent diameter is larger than that of the Sun, at this point in its orbit is large enough to completely cover the solar disk. Two or three times a year, Solar Dynamics Observatory of NASA observed the moon passing in front of the sun, as the right image taken on October 7, 2010.
Image: Comparison of diameters of the Earth and the Moon. File created by NASA in the public domain.
Image: Apparent size of the Moon and the Sun. Credit: NASA/SDO/LRO/GSFC
Size of Earth relative to Sun
Earth is small compared to the Sun, in the volume of the Sun could put more than a million Earths (1,305,620). Its average diameter is ≈ 12 742 km and that of the Sun, ≈ 1,392,684 km (≈ 109 times larger). The image shows the size ratio Earth / Sun, if the Earth stood on the same plane, very close to the Sun. Since April 2010 the mission of the Space Telescope SDO is to examine the sun's magnetic field, it allows a better understanding of the solar atmosphere and the role Sun plays on climate and atmospheric chemistry of the Earth. The telescope has 10 CCDs high quality in visible light which are also designed for the detection of light in the extreme ultraviolet. SDO located on the geosynchronous orbit, provides images with 10 times better than HDTV clarity.
Table: number of planets, contained in a solar volume. How many Earths contains the volume of the Sun?