For Help: [You MUST use the meteorite sample disk] Q2: Did any meteorites show/go through differentiation? Q3: What is the age based on this fact, rank them (aidest-voungest)? Q4. Which of these meteorites is more like a terrestrial planet ortintion and which is more like a jovian? [Extra Credit question] - The first solid particles were microscopic in size. They orbited the Sun in nearly circular orbits right next to each other, as the gas from which they condensed. Gently collisions allowed the flakes to stick together and make larger particles which, in turn, attracted more solid particles. This process is cailed accretion. - The objects formed by accretion are called planetesimals (small planets): they act as seeds for planet formation. At first, planetesimals were closely packed. Thoy coalesced into larger objects, forming clumps of up to a fow kilometers across in a few million years, a small time compared to the age of the solar system. - Once planetesimals had grown to these sizes, collisions became destructive, making further growth more difficult. Only the biggest planetesimals survived this fragmentation process and continued to slowly grow into protoplanets by accretion of planetesimals of similar composition. - After protoplanets formed, accumulation of heat from radioactive decay of short-lived elements melted the planet from within, allowing materials to differentiate (Remember what differenttate means?). Formation of terrestrial planets: - In the warmer inner solar system, planetesimals formed from rock and metal, materials cooked billions of years ago in cores of massive stars. - These elements made up only 0.6% of the material in the solar nebula (and the faster collisions among particles close to the Sun were more destructive on average), so the planets could not grow very large and could not exert large pull on hydrogen and helium gas. - Even if terrestrial planets had hydrogen and helium, proximity to the Sun would heat gasses and cause them to escape. - Hence, terrestrial planets (Mercury Venus, Earth, and Mars) are dense small worlds composed mostly from 2% of heav elements contained in solar nebulae