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While this is quite close, the star LHS 1140 is so dim that the planet only gets 0.43 times the incident flux of Earth at this distance. [2] Assuming an albedo of 0, LHS 1140 b has an equilibrium temperature of 230 K (−43 °C; −46 °F), compared to Earth's at 255 K (−18 °C; −1 °F). If LHS 1140 b has an albedo similar to that of Earth ...
Distances between the planets in the Solar System are often measured in astronomical units (AU), defined as the average distance between the Sun and Earth, some 1.5 × 10 8 kilometers (93 million miles). Venus, the closest planet to Earth is (at closest approach) 0.28 AU away. Neptune, the farthest planet from the Sun, is 29.8 AU away.
The transition between Earth's atmosphere and outer space lacks a well-defined physical boundary, with the air pressure steadily decreasing with altitude until it mixes with the solar wind. Various definitions for a practical boundary have been proposed, ranging from 30 km (19 mi) out to 1,600,000 km (990,000 mi). [15]
This is because the distance between Earth and the Sun is not fixed (it varies between 0.983 289 8912 and 1.016 710 3335 au) and, when Earth is closer to the Sun , the Sun's gravitational field is stronger and Earth is moving faster along its orbital path. As the metre is defined in terms of the second and the speed of light is constant for all ...
Proxima Centauri b is the closest exoplanet to Earth, [19] at a distance of about 4.2 ly (1.3 parsecs). [4] It orbits Proxima Centauri every 11.186 Earth days at a distance of about 0.049 AU, [1] over 20 times closer to Proxima Centauri than Earth is to the Sun. [20] As of 2021, it is unclear whether it has an eccentricity [e] [23] but Proxima Centauri b is unlikely to have any obliquity. [24]
Star 3rd century BC — 1609 380 Earth radii (very inaccurate, true=16000 Earth radii) Aristarchus of Samos made a measurement of the distance of the Sun from the Earth in relation to the distance of the Moon from the Earth. The distance to the Moon was described in Earth radii (20, also inaccurate).
Each spot is a galaxy, consisting of billions of stars. The light from the smallest, most redshifted galaxies originated nearly 13.8 billion years ago. The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40 × 10 26 m) in any direction.
When Venus lies between Earth and the Sun in inferior conjunction, it makes the closest approach to Earth of any planet at an average distance of 41 million km (25 million mi). [4] [note 3] [172] Because of the decreasing eccentricity of Earth's orbit, the minimum distances will become greater over tens of thousands of years.