陨石中发现的富钙铝包体（CAI）如何用作太阳系形成的时间零点？
How are calcium–aluminium inclusions (CAIs) in meteorites used as time zero for Solar System formation?
CAI 是太阳系中最早结晶的高温难熔矿物集合，其铅–铅等同位素定年给出约 45.67 亿年的形成时刻，被约定为太阳系的时间零点。以 CAI 为基准的相对定年（如锰–铬、铝–镁法）可重建各天体的形成次序。
CAIs are the earliest-crystallized, high-temperature refractory minerals in the Solar System; lead–lead dating places them at ~4.567 Gyr, adopted as time zero. CAI-anchored relative dating (Mn–Cr, Al–Mg) reconstructs the formation sequence of bodies.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Connelly 等 2012, Science 338, 651（太阳原行星盘固体绝对年代）
Connelly et al. (2012), Science 338, 651, 'The Absolute Chronology and Thermal Processing of Solids in the Solar Protoplanetary Disk'
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1126/science.1226919：The Absolute Chronol
#富钙铝包体 #铅-铅定年 #太阳系年龄
尼斯模型如何用行星迁移解释外太阳系结构的形成？
How does the Nice model use planetary migration to explain outer Solar System architecture?
尼斯模型假设早期四颗巨行星靠近且外缘有星子盘，行星与盘的引力相互作用引发轨道迁移并触发轨道共振穿越，使木星内移、土星等外移，并散射大量星子——既解释了 LHB，也说明了特洛伊小行星与共轨结构的来源。
The Nice model posits the four giant planets started compact with an outer planetesimal disk; planet–disk interactions drove migration and a resonance-crossing instability, moving Jupiter inward and others outward while scattering planetesimals—explaining the LHB and the origin of Trojans and co-orbital structures.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Tsiganis, Gomes, Morbidelli & Levison 2005, Nature 435, 459（尼斯模型）
Tsiganis, Gomes, Morbidelli & Levison (2005), Nature 435, 459, 'Origin of the orbital architecture of the giant planets of the Solar System'
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1038/nature03539：Origin of the orbital ar
#尼斯模型 #行星迁移 #共振穿越
晚期重轰炸期（LHB）假说认为太阳系早期发生了什么？
What does the Late Heavy Bombardment (LHB) hypothesis propose about early Solar System history?
LHB 假说认为约 41–38 亿年前，巨行星轨道不稳（尼斯模型）导致大量小行星与彗星被抛向内太阳系，在月球与类地行星表面留下密集撞击坑。月球高地撞击坑密度是其主要证据，但具体是否集中爆发仍有争议。
The LHB hypothesis holds that ~4.1–3.8 Gyr ago, giant-planet orbital instability (Nice model) scattered asteroids and comets inward, battering the Moon and terrestrial planets with impact craters. Lunar highland crater density is key evidence, though whether it was a sharp spike remains debated.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据结论有争议 · Contested
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#晚期重轰炸 #尼斯模型 #月球撞击
原行星盘是如何从分子云坍缩中形成的？
How does a protoplanetary disk form from molecular-cloud collapse?
分子云局部密度涨落引发引力坍缩，角动量守恒使下落物质形成绕中心原恒星旋转的扁平盘。盘内尘埃与气体在冷区凝聚成星子，进而吸积成行星。太阳系约 46 亿年前也始于这样的原行星盘（陨石中保存了其成分记录）。
Density fluctuations in a molecular cloud trigger gravitational collapse; angular-momentum conservation flattens infalling matter into a rotating disk around the protostar. Dust and gas condense into planetesimals that accrete into planets. The Solar System, ~4.6 Gyr ago, began in such a disk, recorded in meteorites.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#原行星盘 #分子云 #星子
为什么冥王星被重新归类为矮行星而非行星？
Why was Pluto reclassified as a dwarf planet rather than a planet?
2006 年国际天文学联合会（IAU）定义行星须同时满足环绕太阳、呈流体静力平衡（近球形）并清空其轨道邻域。冥王星质量太小、轨道与海王星外天体群重叠，未清空轨道，故归为矮行星。
In 2006 the IAU defined a planet as orbiting the Sun, being in hydrostatic equilibrium (near-spherical), and having cleared its orbital neighborhood. Pluto is too small and shares its orbit with trans-Neptunian objects, so it is a dwarf planet.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#矮行星 #IAU定义 #冥王星
柯伊伯带与奥尔特云在位置和成分上有何区别？
How do the Kuiper Belt and Oort Cloud differ in location and composition?
柯伊伯带位于海王星轨道外约 30–55 天文单位的盘状区域，主要由冰质天体（水、甲烷、氨冰）组成，是短周期彗星的源地。奥尔特云是延伸至数万天文单位的球壳，由更零散的冰彗体构成，被认为是长周期彗星储库。
The Kuiper Belt is a disk-like region ~30–55 AU beyond Neptune, made of icy bodies (water, methane, ammonia ices) and the source of short-period comets. The Oort Cloud is a spherical shell out to tens of thousands of AU of scattered icy comets, the reservoir of long-period comets.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#柯伊伯带 #奥尔特云 #彗星
地球水的来源更可能是彗星还是小行星？依据是什么？
Is Earth's water more likely from comets or asteroids, and what is the evidence?
氢同位素比对显示，多数彗星的水氘/氢比远高于地球海洋，而一类碳质球粒陨石的水同位素与地球接近。因此主流观点认为地球水主要来自类型相近的小行星，彗星贡献较小。
Hydrogen isotope ratios show most comets have D/H far higher than Earth's oceans, whereas certain carbonaceous chondrites match Earth's water. The prevailing view is that Earth's water came mainly from similar asteroids, with only minor cometary contribution.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#地球水起源 #氘氢比 #碳质球粒陨石
小行星带为何没有聚合成一颗行星？
Why didn't the asteroid belt coalesce into a planet?
火星与木星轨道之间小行星带的星子持续受到木星强引力摄动，轨道被搅动到高速碰撞而非温和吸积，难以长大成行星核。木星的迁移（大迁徙模型）还可能清空并重塑了这一区域。
Planetesimals in the Mars–Jupiter gap were continuously stirred by Jupiter's strong perturbations into high-velocity collisions instead of gentle accretion, preventing growth into a planetary core. Jupiter's migration (Grand Tack) may also have cleared and reshaped the region.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
苏宜,《天文学新概论》第5版,科学出版社
Su Yi, Introduction to Astronomy, 5th ed., Science Press
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787030620477（豆瓣书目条目: 天文学新概论）
#小行星带 #木星摄动 #行星形成