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Theia (/ ˈ θ iː ə /) is a hypothesized ancient planet in the early Solar System which, according to the giant-impact hypothesis, collided with the early Earth around 4.5 billion years ago, with some of the resulting ejected debris coalescing to form the Moon.
By 10 million years, gas in the protoplanetary disc has been blown away, and outer planet formation is likely complete. [39] 10 million – 100 million years 4.5–4.6 bya: Terrestrial planets and the Moon form. Giant impacts occur. Water delivered to Earth. [2] Main sequence 50 million years 4.5 bya: Sun becomes a main-sequence star. [33] 200 ...
A planet's year depends on its distance from its star; the farther a planet is from its star, the longer the distance it must travel and the slower its speed, since it is less affected by its star's gravity. No planet's orbit is perfectly circular, and hence the distance of each from the host star varies over the course of its year.
[31] [68] Searches as of 2011 have found that core accretion is likely the dominant formation mechanism. [68] Giant planet core formation is thought to proceed roughly along the lines of the terrestrial planet formation. [20] It starts with planetesimals that undergo runaway growth, followed by the slower oligarchic stage. [65]
Artist's depiction of a collision between two planetary bodies. Such an impact between Earth and a Mars-sized object likely formed the Moon.. The giant-impact hypothesis, sometimes called the Theia Impact, is an astrogeology hypothesis for the formation of the Moon first proposed in 1946 by Canadian geologist Reginald Daly.
A blanet is a member of a hypothetical class of exoplanets that directly orbit black holes. [1]Blanets are fundamentally similar to other planets; they have enough mass to be rounded by their own gravity, but are not massive enough to start thermonuclear fusion and become stars.
OGLE-2005-BLG-390Lb (known sometimes as Hoth by NASA [1]) is a super-Earth ice exoplanet orbiting OGLE-2005-BLG-390L, a star 21,500 ± 3,300 light-years (6,600 ± 1,000 parsecs) from Earth near the center of the Milky Way, making it one of the most distant planets known.
According to the assessment of UNESCO, "The karst formation of Phong Nha-Kẻ Bàng National Park has evolved since the Palaeozoic (some 400 million years ago) and so is the oldest major karst area in Asia" and "Phong Nha displays an impressive amount of evidence of earth's history. It is a site of very great importance for increasing our ...