什么是奥尔特云？它与彗星有什么关系？
What is the Oort Cloud, and what does it have to do with comets?
奥尔特云是假想中包裹太阳系的巨大球壳，距太阳约2000到10万天文单位，储存了上万亿颗冰质天体。长周期彗星就源于此处，受附近恒星引力扰动后飞向太阳。它被认为是太阳系形成时遗留的『原始冰库』。
The Oort Cloud is a hypothetical vast spherical shell around the solar system, from about 2,000 to 100,000 astronomical units out, holding trillions of icy bodies. Long-period comets come from there, nudged Sunward by passing stars. It is thought to be a primordial 'ice reservoir' left from formation.
难度 专业 · 适合 高中(15-18)
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）
#奥尔特云 #彗星 #太阳系边缘
碳质球粒陨石为什么对研究太阳系起源很重要？
Why are carbonaceous chondrites important for studying solar-system origins?
碳质球粒陨石含有水、有机分子和保存了太阳系形成早期的原始物质，几乎未被加热改造。它们被认为是构建地球等岩质行星的原料之一，还可能是地球水和生命前体物质的来源。分析它们等于直接读取46亿年前的『时间胶囊』。
Carbonaceous chondrites contain water, organic molecules and pristine material from the solar system's birth, barely altered by heating. They are thought to be building blocks of rocky planets like Earth and may have delivered its water and prebiotic matter. Studying them is like reading a 4.6-billion-year-old time capsule.
难度 专业 · 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）
#陨石 #碳质球粒 #太阳系起源
小行星按光谱可以分成哪几类？
What spectral classes are asteroids divided into?
天文学家按反射光谱把小行星大致分为C、S、M等类型：C型富含碳质、颜色偏暗，最常见；S型以硅酸盐岩石为主；M型富含金属，可能是破碎行星核的残片。分类有助于推断它们的成分和起源。
By reflection spectra, asteroids are grouped into classes like C, S and M: C-type are dark, carbon-rich and most common; S-type are silicate rocks; M-type are metallic, possibly fragments of broken planetary cores. Classification helps infer composition and origin.
难度 专业 · 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）
#小行星 #光谱分类 #碳质
通古斯大爆炸可能是小行星造成的吗？
Could the Tunguska event have been caused by an asteroid?
1908年西伯利亚通古斯地区发生猛烈空中爆炸，摧毁约2000平方公里森林却没留下陨石坑。主流解释是一颗直径数十米的小天体在大气层中空爆，可能是小行星或彗星碎片。它警示了近地小天体撞击的现实威胁。
In 1908 a violent aerial explosion flattened about 2,000 square kilometers of Siberian forest with no impact crater. The leading explanation is a small body tens of meters across that airburst in the atmosphere, perhaps an asteroid or comet fragment. It warns of the real threat from near-Earth objects.
难度 专业 · 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）
#通古斯 #小行星 #空爆
水星近日点为什会出现无法用牛顿引力完全解释的偏移？
Why does Mercury's perihelion shift in a way Newton's gravity cannot fully explain?
水星椭圆轨道的近日点每世纪比牛顿理论预测多偏移约43角秒，这一异常长期困扰天文学家。爱因斯坦的广义相对论把太阳引力解释为时空弯曲，恰好算出了这多出的进动。这一成功成为广义相对论早期的重要验证之一。
Mercury's perihelion advances about 43 arc-seconds per century more than Newton's theory predicts, a puzzle for a long time. Einstein's general relativity explains the Sun's gravity as curved spacetime and exactly accounts for the extra precession. This success became an early key test of general relativity.
难度 专业 · 适合 高中(15-18)
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）
#水星 #近日点进动 #相对论
人类为什么要研究小行星采矿？
Why are scientists interested in asteroid mining?
某些近地小行星富含铁、镍、铂族金属甚至水冰，水可分解成火箭燃料、金属可用于太空建造。相比从地球发射物资，利用太空就地资源能大幅降低深空任务成本。它被视为未来太空经济和长期驻留的关键。
Some near-Earth asteroids are rich in iron, nickel, platinum-group metals and even water ice, which can be split into rocket fuel while metals build in space. Using space resources is far cheaper than launching supplies from Earth for deep missions. It is seen as key to a future space economy and long stays.
难度 专业 · 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 #采矿 #资源
球粒陨石中的富钙铝包体为何被视为太阳系最早凝结的固体?对其开展的 Pb-Pb 定年如何确立太阳系年龄的时间零点?
Why are calcium-aluminium-rich inclusions in chondritic meteorites regarded as the earliest condensed solids of the Solar System, and how does their Pb-Pb dating establish the zero point of its age scale?
这类包体由黄长石、深绿辉石(fassaite)和尖晶石等难熔矿物组成,记录了约 1700 K 以上高温星云气体的冷凝序列,结晶时间比绝大多数球粒早一到三百万年。Pb-Pb 同位素体系给出的年龄集中在 4567.3 Ma 附近,不确定度仅数十万年,被采纳为太阳系演化的绝对时间零点。借助该锚点,球粒形成、行星核幔分异等相对时标才能换算为确定的纪年。
These inclusions consist of refractory minerals such as melilite, fassaite, and spinel, recording condensation sequences from nebular gas hotter than about 1700 K and crystallizing one to three million years before most chondrules. Their Pb-Pb isotope systematics cluster near 4567.3 Ma with uncertainties of only a few hundred thousand years, defining the absolute zero point of Solar System evolution. Anchored there, relative timescales for chondrule formation and planetary core-mantle differentiation convert into definite calendar ages.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Connelly 等,Science 338:651 (2012);MacPherson,Treatise on Geochemistry 第二版第一卷 1.4 节 (2014)
Connelly et al., Science 338, 651 (2012); MacPherson, Treatise on Geochemistry 2nd ed., vol. 1, sec. 1.4 (2014)
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1126/science.1226919
#球粒陨石 #同位素定年
为什么彗星的尾巴总是指向背离太阳的方向？
Why does a comet's tail always point away from the Sun?
彗星靠近太阳时，冰升华产生气体和尘埃，形成彗发和彗尾。太阳风把离子吹向背离太阳的一侧，形成离子尾；尘埃受辐射光压也偏向远离太阳的方向，形成尘埃尾。因此无论彗星朝哪飞，尾巴都朝外。
As a comet nears the Sun, its ices sublimate into gas and dust, forming a coma and tails. The solar wind blows ions away from the Sun into an ion tail, while radiation pressure pushes dust outward into a dust tail. So whichever way the comet travels, its tails always point away from the Sun.
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
Carl Sagan,《Cosmos》Random House,1980;中译《宇宙》
C. Sagan, Cosmos, Random House, 1980; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9780394502946（按标识回读: Cosmos）
#彗星 #彗尾 #太阳风
什么是近地小行星？它们危险吗？
What are near-Earth asteroids, and are they dangerous?
近地小行星是轨道与地球轨道相近、可能接近地球的小天体。绝大多数体积很小且不会撞击地球，但较大的近地天体若撞击会造成区域甚至全球灾难。天文学家正持续监测并研究偏转技术以应对潜在威胁。
Near-Earth asteroids are small bodies whose orbits come close to Earth's. Most are tiny and pose no threat, but a larger one could cause regional or global disaster if it hit. Astronomers monitor them continuously and study deflection methods against potential threats.
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）
#近地小行星 #监测 #撞击
小行星带位于太阳系的什么位置？
Where is the asteroid belt located?
小行星带主要位于火星和木星轨道之间，距太阳约2.2到3.2天文单位，聚集了数百万计的小天体。木星的强大引力阻止了它们聚合成一颗行星。虽然数量众多，但彼此间距很大，探测器穿越时并不危险。
The main asteroid belt lies between the orbits of Mars and Jupiter, about 2.2 to 3.2 astronomical units from the Sun, holding millions of small bodies. Jupiter's strong gravity prevented them from accreting into a planet. Though numerous, they are far apart, so probes cross safely.
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）
#小行星带 #木星 #火星
彗星是由什么构成的？
What are comets made of?
彗星被称为『脏雪球』，主要由水冰、二氧化碳冰、甲烷冰混合岩石尘埃组成，核心直径通常几到几十公里。远离太阳时它只是一个冰封的核，靠近太阳才活跃起来喷出气体和尘埃。它们被认为是太阳系早期物质的活化石。
Comets are 'dirty snowballs' of water, carbon-dioxide and methane ices mixed with rock and dust, with nuclei a few to tens of kilometers across. Far from the Sun they are frozen cores; only near the Sun do they wake up and vent gas and dust. They are thought to be frozen relics of the early solar system.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
惠普尔 1950 年《天体物理学报》(ApJ) 彗星『脏雪球』模型
Whipple (1950, ApJ) 'dirty snowball' comet model
#彗星 #冰 #脏雪球
为什么彗星靠近太阳时会长出彗尾,而小行星不会?
Why do comets grow tails as they approach the Sun while asteroids generally do not?
彗星本质上是混有尘埃的冰质天体,当它们进入距太阳约3–5个天文单位的区域时,水冰等挥发物直接升华,释放出的气体和尘埃在太阳辐射压与太阳风的作用下分别吹向背离太阳的方向,形成离子彗尾和尘埃彗尾。小行星主要形成于太阳系内区,挥发物早已耗尽或从未大量存在,因此表面只呈现反射光点。不过也存在双重身份的天体,例如主带彗星,说明两类天体之间的界限并不绝对。
Comets are ice-rich bodies mixed with dust; inside roughly 3-5 AU from the Sun, volatiles such as water ice sublimate, and the released gas and dust are pushed antisunward by solar radiation pressure and the solar wind, forming separate ion and dust tails. Asteroids formed mostly in the inner solar system where their volatiles were exhausted or never abundant, so they merely reflect sunlight. Objects like main-belt comets blur the boundary between the two populations.
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）
#彗尾机制 #升华挥发物
主带小行星和彗核在成分与轨道上有何本质区别?为何存在“主带彗星”?
What fundamentally distinguishes main-belt asteroids from comet nuclei in composition and orbit, and why do "main-belt comets" exist?
主带小行星形成于雪线以内,以硅酸盐和金属为主,轨道倾角和偏心率适中,长期保持无活动状态;彗核则形成于外太阳系,保留了大量水冰和一氧化碳等挥发分,接近太阳时升华产生彗发和彗尾。然而小行星带并非完全干燥,部分位于主带内侧的冰质小行星在近日点附近也会出现尘埃彗发,被称为活动小行星或主带彗星。它们保留了原始挥发布,说明主带的冰可以在浅层存活数十亿年,是研究内太阳系水来源的重要对象。
Main-belt asteroids formed inside the snow line and are dominated by silicates and metal, with modest eccentricities and inclinations that keep them inactive; comet nuclei formed in the outer Solar System and retain abundant water ice and volatiles like CO, which sublimate near perihelion to produce a coma and tail. Yet the belt is not perfectly dry: some icy asteroids well inside the belt develop dust comas near perihelion and are classed as active asteroids or main-belt comets. Their preserved volatile inventory shows shallow ice can survive billions of years in the belt, making them key targets for studying the origin of water in the inner Solar System.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Hsieh & Jewitt 2006, Science 312, 561《主带中的彗星》
Hsieh & Jewitt 2006, Science 312, 561, "A Population of Comets in the Main Asteroid Belt"
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1126/science.1125150：A Population of Come
#主带彗星 #挥发性物质
恐龙灭绝和小行星撞击有关吗？
Did an asteroid impact cause the dinosaur extinction?
科学界普遍认为约6600万年前一颗约10公里宽的小行星撞击今墨西哥尤卡坦半岛，引发了恐龙等大量生物灭绝。撞击扬起的尘埃遮蔽阳光，导致全球变冷和光合作用中断。这一撞击坑被称为希克苏鲁伯。
Most scientists agree that about 66 million years ago an asteroid roughly 10 kilometers wide hit what is now the Yucatan Peninsula in Mexico, causing the mass extinction of the dinosaurs and many other species. Dust from the impact blocked sunlight, cooling the globe and halting photosynthesis. The crater is called Chicxulub.
难度 入门 · 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）
#小行星 #灭绝 #撞击
什么是流星雨？
What is a meteor shower?
流星雨是地球穿过彗星留下的尘埃带时，大量尘埃高速冲入大气燃烧形成的现象。因为透视效果，这些流星看起来都从天空中的同一个点（辐射点）散开。著名的例子有每年8月的英仙座流星雨。
A meteor shower occurs when Earth passes through the dust trail left by a comet and lots of particles burn up in the atmosphere. Due to perspective, the meteors appear to radiate from a single point in the sky called the radiant. A famous example is the Perseids every August.
难度 入门 · 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）
#流星雨 #彗星 #尘埃
流星、流星体和陨石有什么区别？
What is the difference between a meteor, a meteoroid and a meteorite?
流星体是太空中飘浮的岩石或金属碎块。当它闯入地球大气、因摩擦发光划过夜空时，那一刻的光迹叫流星。若残骸落到地面，就称为陨石。
A meteoroid is a rock or metal fragment drifting in space. When it plunges into Earth's atmosphere and glows from friction, the streak of light is called a meteor. If debris survives and lands on the ground, it is called a meteorite.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Carl Sagan,《Cosmos》Random House,1980;中译《宇宙》
C. Sagan, Cosmos, Random House, 1980; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 DOUBAN ISBN 标识 9780394502946（按标识回读: Cosmos）
#流星 #陨石 #流星体