Caption: Figures from the Nice model (named for Nice, France), a computer simulation of planetary migration.

The Nice model is not the last word in the Solar System formation and evolution.

The planet orbits shown are:

1. Jupiter in green.
2. Saturn in orange.
3. Uranus in light blue.
4. Neptune in dark blue.

The Kuiper Belt objects (KBOs) are shown as white dots. KBOs are rocky-icy bodies that in the modern Solar System orbit from about 30 AU (i.e., about the radius of the orbit of Neptune) to about 50 AU. The region of the KBOs is---surprise---called the Kuiper belt. KBOs fall into the larger class of trans-Neptunian objects (TNOs).

The epochs shown in the computer simulation are:

1. Before Jupiter and Saturn pass through a 2:1 orbital resonance (i.e., 2 Jupiter orbital periods to 1 of Saturn).
2. Scattering of KBOs to within some of the planet orbits??? after the orbital shift of Neptune.
3. After ejection of KBOs by Jupiter.

Credit/Permission: © Mark Booth (AKA User:AstroMark), before or circa 2008 (uploaded to Wikimedia Commons by User:Poppy, 2008) / CC BY-SA 3.0.
Image link: Wikimedia Commons.
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