https://phys.org/news/2017-06-evidence-jupiter-oldest-planet-solar.html Jupiter's early formation acted as an effective barrier against inward transport of material across the solar system disk, potentially explaining why our solar system lacks any super-Earths. Effectivelly protecting the Earth. Jupiter's core grew to about 20 Earth masses within 1 million years, then to about 50 Earth masses for 3-4 million years before it's final 300 EMs. via Evidence that Jupiter is the oldest planet in the solar system.