Today, the Nice model offers the predominant understanding of how a disc of dust and gas about 4.6 billion years ago became a system of planets circling a sun.

The regions both lead and follow Jupiter in its orbit. Some comets and asteroids were flung to the deep outer solar system, and others were ejected entirely out into the Milky Way.ДЄ small minority of scattered asteroids were ensnared in two of JupiterвЂ™s permanent Lagrange points, which are regions of space where the gravitational and orbital influences of the planet and the sun are balanced. In the process, as the giant planets moved, and Uranus and Neptune bounded outward, they scattered the small bodies of the solar system. The model suggests that the giant planets formed much closer to the sun than their current orbits, and that the increasingly eccentric orbits of a young Jupiter and Saturn destabilized and rearranged the solar system. The NASA team hopes that the robotic Lucy does the same for the solar systemвЂ™s evolution, and prehistory is a recurring theme among the missionвЂ™s scientists. The mission name вЂњLucyвЂќ is a nod to the 3.2 million-year-old australopithecine skeleton discovered in 1974, which revealed secrets of human evolution. The result was the overall descriptor of вЂњTrojan.вЂќ When the first was spotted more than a century ago, astronomers began naming them after heroes of HomerвЂ™s Iliad. About 10,000 such objects have been discovered. And the New Horizons mission visited Arrokoth, an object in the solar systemвЂ™s distant Kuiper belt.Д«ut the Trojans in JupiterвЂ™s vicinity have yet to be investigated. JapanвЂ™s Hayabusa missions and NASAвЂ™s OSIRIS-REX completed close encounters with near earth asteroids. The Dawn mission orbited Ceres and Vesta, the two largest worlds in the belt between Mars and Jupiter.

The NEAR mission landed on Eros in the inner asteroid belt. Humanity has explored a variety of small rocky bodies throughout the solar system. вЂњEvery time weвЂ™ve done that, weвЂ™ve learned more and more about our solar system and the area in space that we live in.вЂќ вЂњItвЂ™s always interesting to go somewhere for the first time,вЂќ said Cathy Olkin, the deputy principal investigator of the Lucy mission.

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