小行星 vs 彗星 vs 流星
了解这些太空天体之间的关键区别，从它们的组成和起源到它们在夜空中的壮观表现。
快速解答
小行星是岩石天体，彗星是在靠近太阳时会形成彗尾的冰冷天体，流星是小颗粒在地球大气层中燃烧时产生的明亮光迹。主要区别在于组成：小行星是岩石和金属，彗星是冰和尘埃。
- 由岩石和金属组成
- 主要位于小行星带
- 圆形轨道，内太阳系
- 冰、尘埃和冷冻气体
- 柯伊伯带和奥尔特云
- 靠近太阳时形成彗尾
- 小型岩石或金属碎片
- 在地球大气层中燃烧
- 明亮的光迹
详细对比
| 属性 | 小行星 | 彗星 | 流星 |
|---|---|---|---|
| Composition | Rock and metal (silicates, iron, nickel) | Ice, dust, rock, and frozen gases (water, CO2, methane) | Small rock or metal fragments |
| Size | 1 meter to 1,000 km (Ceres is largest) | 1-50 km nucleus (tail can extend millions of km) | Dust grain to 1 meter |
| Location | Mainly asteroid belt (between Mars & Jupiter) | Kuiper Belt & Oort Cloud (outer solar system) | Earth's atmosphere (when burning up) |
| Orbit | Mostly circular, same plane as planets | Highly elliptical, can be inclined | N/A (becomes meteor when entering atmosphere) |
| Tail | No tail | Develops tail when near Sun (gas and dust) | Bright streak (burning trail) |
| Nickname | "Minor planets" or "planetoids" | "Dirty snowballs" or "icy dirt balls" | "Shooting stars" |
什么是彗星？
- 彗核
固体核心（1-50公里），由冰、尘埃和岩石组成——通常被称为「脏雪球」
- 彗发
靠近太阳时围绕彗核的气体和尘埃形成的模糊大气层
- 彗尾
两种类型：蓝色离子尾（气体）直指太阳相反方向，白色/黄色尘埃尾沿轨道弯曲
- • 彗星通常被称为「脏雪球」或「冰冷尘球」
- • 彗星的尾巴总是背向太阳，因为受到太阳风的作用
- • 短周期彗星来自柯伊伯带，长周期彗星来自奥尔特云
- • 哈雷彗星每75-76年回归一次（下次：2061年）
- • 彗星可能为早期地球带来了水和有机分子
什么是小行星？
- C型（碳质）
最常见（约75%），颜色暗淡，富含碳，位于外小行星带
- S型（硅质）
第二常见（约17%），岩石质，硅酸盐矿物，位于内小行星带
- M型（金属质）
稀有但有价值，铁镍组成，可能是被摧毁的原行星核心
- • 我们太阳系已编目超过130万颗小行星
- • 谷神星是最大的小行星（940公里），也被归类为矮行星
- • 所有小行星的总质量不到月球的质量
- • 一些小行星有自己的卫星（如艾达和它的卫星达克提尔）
- • 近地小行星受到监测以防潜在撞击风险
流星 vs 陨石 vs 流星体
流星体
在太空中穿行的小型岩石或颗粒，大小从尘埃粒到1米不等
流星
流星体在地球大气层中燃烧时产生的明亮光迹——也称为「流星」
陨石
穿过大气层后幸存并落在地球表面的流星体
常见问题
The main difference is composition: asteroids are made of rock and metal, while comets are made of ice, dust, and frozen gases. Asteroids orbit in the inner solar system (mainly the asteroid belt), while comets come from the outer solar system (Kuiper Belt and Oort Cloud). Comets develop tails when near the Sun; asteroids do not.
A meteoroid is a small rock or particle in space. When a meteoroid enters Earth's atmosphere and burns up, creating a streak of light, it's called a meteor (or 'shooting star'). If any part survives and lands on Earth, it becomes a meteorite.
Some objects blur the line between asteroids and comets. 'Active asteroids' or 'main-belt comets' are objects in the asteroid belt that occasionally show comet-like activity. Scientists now recognize that the distinction isn't always clear-cut.
Comets are made of ice (water, carbon dioxide, methane, ammonia), dust, and rocky material. They're often called 'dirty snowballs' because they're primarily ice mixed with dark organic material. When heated by the Sun, the ice sublimates (turns to gas), creating the characteristic coma and tail.
Most comets come from two regions: the Kuiper Belt (30-50 AU from the Sun, source of short-period comets) and the Oort Cloud (2,000-100,000 AU away, source of long-period comets). Some rare comets, like 3I/ATLAS, come from outside our solar system entirely - these are called interstellar comets.
An interstellar comet is a comet that originated from another star system and is passing through our solar system. Only three have been confirmed: 1I/'Oumuamua (2017), 2I/Borisov (2019), and 3I/ATLAS (2025). They travel on hyperbolic orbits and will never return to our solar system.