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Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin [4] [5] based on its characteristics; also known by its Kepler object of interest designation KOI-7016.01) is a candidate [6] [7] super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope.
Aristarchus of Samos (/ ˌ æ r ə ˈ s t ɑːr k ə s /; Ancient Greek: Ἀρίσταρχος ὁ Σάμιος, Aristarkhos ho Samios; c. 310 – c. 230 BC) was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the universe, with the Earth revolving around the Sun once a year and rotating about its axis once a day.
In such systems the origin in the center of mass of the Earth, of the Earth–Moon system, of the Sun, of the Sun plus the major planets, or of the entire Solar System, can be selected. [165] Right ascension and declination are examples of geocentric coordinates, used in Earth-based observations, while the heliocentric latitude and longitude ...
The idea that the Earth was formed elsewhere and then migrated to orbit around the Sun does not accord with the scientific understanding of Earth's formation, which is that the Earth formed in orbit around the Sun about 4.5 billion years ago by accretion from a protoplanetary disk, and has remained near its original orbit until the present.
The first report of an exoplanet within this range was in 1998 for a planet orbiting around Gliese 876 (15.3 light-years (ly) away), and the latest as of 2024 is one around Struve 2398 A (11.5 ly). The closest exoplanets are those found orbiting the star closest to the Solar System, which is Proxima Centauri 4.25 light-years away
The planet is higher in the sky and less atmospheric effects affect the view of the planet. Mercury can be viewed as close as 4° to the Sun near superior conjunction when it is almost at its brightest. Mercury can, like several other planets and the brightest stars, be seen during a total solar eclipse. [150]
For the giant planets, the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure. [ 11 ] Because Sedna and 2002 MS 4 have no known moons, directly determining their mass is impossible without sending a probe (estimated to be from 1.7x10 21 to 6.1×10 21 kg for Sedna [ 12 ] ).
Near the time of the equinoxes, the Sun faces the equator of Uranus, giving a period of day–night cycles similar to those seen on most of the other planets. One result of this axis orientation is that, averaged over the Uranian year, the near-polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions.