They show that most of the molybdenum in Earth's mantle was supplied by the
protoplanet Theia, whose collision with Earth 4.4 billion years ago led to the formation of the Moon.
In the July 1st Astrophysical Journal, the team concludes that 4 billion years ago, a rock-and-ice
protoplanet with at least twice Earth's mass collided with Uranus and knocked it over.
The Dawn spacecraft had a very specific mission in mind to complete, and it was to study the largest objects in the asteroid belt -
protoplanet Vesta and the dwarf planet Ceres.
(2014) Recovery of the candidate
protoplanet HD 100546 b with Gemini/NICI and detection of additional (planet-induced?) disk structure at small separations.
In the case of
protoplanet LkCa 15 b, hydrogen atoms were heated up to nearly 10,000 degrees Celsius (18,000 Fahrenheit).
Researchers think that Ceres is an intact
protoplanet, a fossil from the beginning of the solar system.
In March, NASA's Dawn probe will arrive at
protoplanet Ceres, the most massive body in the asteroid belt between Mars and Jupiter.
(2002), "Formation of
Protoplanet Systems and Diversity of Planetary Systems," The Astrophysical Journal 581(1): 666-680.
He pointed out that the Dawn spacecraft, which since last summer has orbited the Asteroid Belt's second largest object, the
protoplanet Vesta; will soon use ion propulsion to embark on a flight to orbit the dwarf planet Ceres in 2015.
The one that is favored by most planetary scientists is termed the Giant Impact Theory or, much less formally, the Big Whack, in which a Mars-sized
protoplanet, named Theia by astronomers, smashed into the primordial Earth about 4,500,000,000 years ago, when our solar system was taking shape.
(1) is evaluated over the entire spherical surface of a slowly rotating
protoplanet and the approximation is made as in Bhattacharjee (1983), then we can write