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In many cases it is not possible to have an exact value, and an estimated range is instead provided. The coldest and oldest planet directly imaged is Epsilon Indi Ab, which has six times Jupiter's mass, an effective temperature of 275 K, and an age of about 3.5 Ga. This list includes the four members of the multi-planet system that orbit HR 8799.
A classical planet is an astronomical object that is visible to the naked eye and moves across the sky and its backdrop of fixed stars (the common stars which seem still in contrast to the planets). Visible to humans on Earth there are seven classical planets (the seven luminaries ).
Gonggong (minor-planet designation: 225088 Gonggong) is a dwarf planet and a member of the scattered disc beyond Neptune.It has a highly eccentric and inclined orbit during which it ranges from 34–101 astronomical units (5.1–15.1 billion kilometers; 3.2–9.4 billion miles) from the Sun.
Mars is the fourth planet from the Sun.The surface of Mars is orange-red because it is covered in iron(III) oxide dust, giving it the nickname "the Red Planet". [22] [23] Mars is among the brightest objects in Earth's sky, and its high-contrast albedo features have made it a common subject for telescope viewing.
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 ] ).
HD 189733 b is an exoplanet in the constellation of Vulpecula approximately 64.5 light-years (19.8 parsecs) away [7] from the Solar System.Astronomers in France discovered the planet orbiting the star HD 189733 on October 5, 2005, by observing its transit across the star's face. [1]
In these celestial models, the apparent motions of the fixed stars and planets are accounted for by treating them as embedded in rotating spheres made of an aetherial, transparent fifth element (quintessence), like gems set in orbs. Since it was believed that the fixed stars did not change their positions relative to one another, it was argued ...
Schematic diagram of the orbits of the fictional planets Vulcan, Counter-Earth, and Phaëton in relation to the five innermost planets of the Solar System.. Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to hypothetical planets that have at one point or another been seriously proposed by real-world astronomers, though commonly ...