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If Jupiter had Mercury's orbit (57,900,000 km, 0.387 AU), the Sun–Jupiter barycenter would be approximately 55,000 km from the center of the Sun ( r 1 / R 1 ≈ 0.08). But even if the Earth had Eris's orbit (1.02 × 10 10 km, 68 AU), the Sun–Earth barycenter would still be within the Sun (just over 30,000 km from the center).
The astronomical unit of length is now defined as exactly 149 597 870 700 meters. [4] It is approximately equal to the mean Earth–Sun distance. It was formerly defined as that length for which the Gaussian gravitational constant (k) takes the value 0.017 202 098 95 when the units of measurement are the astronomical units of length, mass and ...
The astronomical unit is too small to be convenient for interstellar distances, where the parsec and light-year are widely used. The parsec (parallax arcsecond) is defined in terms of the astronomical unit, being the distance of an object with a parallax of 1″. The light-year is often used in popular works, but is not an approved non-SI unit ...
Center-to-center distance Altitude above the Earth's surface Speed Orbital period Specific orbital energy; Earth's own rotation at surface (for comparison— not an orbit) 6,378 km: 0 km: 465.1 m/s (1,674 km/h or 1,040 mph) 23 h 56 min 4.09 sec: −62.6 MJ/kg: Orbiting at Earth's surface (equator) theoretical 6,378 km: 0 km
A parsec is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond (not to scale). The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles).
Its diameter is eleven times that of Earth, and a tenth that of the Sun. Jupiter orbits the Sun at a distance of 5.20 AU (778.5 Gm), with an orbital period of 11.86 years. It is the third-brightest natural object in the Earth's night sky, after the Moon and Venus, and has been observed since prehistoric times.
Ignoring the influence of other Solar System bodies, Earth's orbit, also called Earth's revolution, is an ellipse with the Earth–Sun barycenter as one focus with a current eccentricity of 0.0167. Since this value is close to zero, the center of the orbit is relatively close to the center of the Sun (relative to the size of the orbit).
It is similar to Earth in size and mass and is often described as Earth's "sister" or "twin". [33] Venus is close to spherical due to its slow rotation. [ 34 ] Venus has a diameter of 12,103.6 km (7,520.8 mi)—only 638.4 km (396.7 mi) less than Earth's—and its mass is 81.5% of Earth's, making it the third-smallest planet in the Solar System .