According to the standard theory, the Earth is thought to have formed from the collision of small celestial bodies known as planetesimals
. Since such bodies were poor in water, Earth's water must have been delivered either by a larger planetesimal
or by a shower of smaller objects such as asteroids or comets.
Scientists think that the lobes of the Ultima Thule are "primordial planetary building blocks called planetesimals
The Trappist-1 system is named after the Transiting Planets and Planetesimals
Small Telescope (TRAPPIST) in Chile, which discovered two of the planets in the system in February 2016.
In the so-called Nice Model, the giant planets that orbit our own Sun migrated inward and outward as they were forming, launching many planetesimals
into interstellar space.
Both the asteroids and comets are relic planetesimals
. The vast primordial population of ancient planetesimals
served as the building blocks of the eight major planets of the sun's family.
In one, it occurs in stages, with small dust particles coalescing into "planetesimals
" -- rock fragments ten to 100 kilometers in diameter -- that collide to form planetary embryos, and then planets, over a time scale of 50 to 100 million years.
In most models it is considered that the protoplanetary disk is formed by a distribution of continuous material, which as it rotates around the star, acquires dynamics (stable and / or turbulent), so that originates planets through a process of accretion of planetesimals
The discovery was made using Europe's Transiting Planets and Planetesimals
Small Telescope, or TRAPPIST, located at the La Silla Observatory in Chile.
The researchers used the Transiting Planets and Planetesimals
Small Telescope (TRAPPIST) to find the three Earth-like planets.
"It's the perfect recipe if you want to form planets or planetesimals
," said Isella, of Rice University in Houston.
The current leading theory for planetary formation is the core-accretion model, in which a heavy element core is built by the accretion of planetesimals
. As the core grows, its ability to accrete gas from the surrounding disk increases.