The massive cores of the giant planets are thought to have formed in a gas disk by the accretion of pebble-sized particles whose accretional cross-section was enhanced by aerodynamic gas drag^1,2. A commonly held view is that the terrestrial planet system formed later (30–200 Myr after the dispersal of the gas disk) by giant collisions of tens of lunar- to Mars-sized protoplanets^3,4. Here we propose, instead, that the terrestrial planets of the Solar System formed earlier by the gas-driven convergent migration of protoplanets towards ~1 au. To investigate situations in which convergent migration occurs and determine the thermal structure of the gas and pebble disks in the terrestrial planet zone, we developed a radiation–hydrodynamic model with realistic opacities^5,6. We find that protoplanets grow in the first 10 Myr by mutual collisions and pebble accretion, and gain orbital eccentricities by gravitational scattering and the hot-trail effect^7,8. The orbital structure of the inner Solar System is well reproduced in our simulations, including its tight mass concentration at 0.7–1 au and the small sizes of Mercury and Mars. The early-stage protosolar disk temperature exceeds 1,500 K inside 0.4 au, implying that Mercury grew in a highly reducing environment next to the evaporation lines of iron and silicates, influencing Mercury’s bulk composition⁹. A dissipating gas disk, however, is cold, and pebbles drifting from larger heliocentric distances would deliver volatile elements.

巨行星的巨大核心被认为是由卵石大小的粒子吸积形成的气盘，这些颗粒的吸积横截面因气动气体阻力^1,2而增强。一个普遍持有的观点是，类地行星系统是由数十颗月球到火星大小的原行星^{3,4 的}巨大碰撞形成的（气盘分散后 30-200 Myr）。相反，在这里我们提出，太阳系的类地行星是由气体驱动的原行星向约 1 au 的汇聚迁移形成的。为了研究发生会聚迁移的情况并确定类地行星带中气体和卵石盘的热结构，我们开发了具有实际不透明度的辐射-流体动力学模型^5,6. ^{我们发现原行星在前 10 Myr 通过相互碰撞和卵石吸积而生长，并通过引力散射和热轨效应7,8}获得轨道偏心率。内太阳系的轨道结构在我们的模拟中得到了很好的再现，包括它在 0.7-1 au 的紧密质量浓度以及水星和火星的小尺寸。早期的原太阳盘温度在 0.4 au 内超过 1,500 K，这意味着水星在铁和硅酸盐蒸发线旁边的高度还原环境中生长，影响了水星的整体组成⁹。然而，一个正在消散的气体盘是冷的，从较大的日心距离漂移的鹅卵石会释放出挥发性元素。