柯伊伯带和奥尔特云
发现太阳系外围彗星诞生的神秘区域。从冰冷的柯伊伯带到遥远的奥尔特云，探索这些宇宙旅行者的起源。
快速解答
柯伊伯带（距太阳30-50天文单位）是海王星轨道外的冰冷天体环带，是短周期彗星的发源地。奥尔特云（2,000-100,000天文单位）是包围太阳系的巨大球壳，是长周期彗星的来源。像3I/ATLAS这样的星际天体则完全来自太阳系之外。
它们有多远？
什么是柯伊伯带？
柯伊伯带是从海王星轨道（30天文单位）延伸到距太阳约50天文单位的环形冰冷天体区域。它包含数百万个太阳系形成时遗留下来的冰冻天体。
- 位于距太阳30-50天文单位处（海王星之外）
- 包含数百万个称为KBO的冰冷天体
- 短周期彗星的来源（轨道周期<200年）
1930年发现，2015年新视野号探测器访问
比冥王星略小但质量更大
最亮的柯伊伯带天体之一，2005年发现
什么是奥尔特云？
奥尔特云是太阳系边缘理论上存在的冰冷天体球壳。据信包含数万亿个冰冷天体，标志着太阳引力影响的边界。
- 从距太阳2,000到100,000天文单位延伸
- 估计包含超过万亿个冰冷天体
- 长周期彗星的来源（轨道周期>200年）
内奥尔特云（希尔斯云）
2,000-20,000天文单位，盘状，密度较高
外奥尔特云
20,000-100,000天文单位，球形，松散束缚的天体
按起源分类的彗星类型
- • 起源于柯伊伯带
- • 在与行星相同的平面上运行
- • 回归日期更可预测
- • 起源于奥尔特云
- • 可从任何方向接近
- • 通常在人类历史上只出现一次
常见问题
The Kuiper Belt is a doughnut-shaped region of icy bodies beyond Neptune's orbit, extending from about 30 to 50 AU from the Sun. It contains millions of frozen objects, including dwarf planets like Pluto and Eris. It's the source of short-period comets that orbit the Sun in less than 200 years.
The Oort Cloud is a theoretical spherical shell of icy objects surrounding the solar system at distances of 2,000 to 100,000 AU from the Sun. It's believed to contain trillions of icy bodies and is the source of long-period comets that take more than 200 years to orbit the Sun.
Comets originate from two main regions: the Kuiper Belt (short-period comets) and the Oort Cloud (long-period comets). Both regions contain remnants from the solar system's formation 4.6 billion years ago. Some rare comets, like 3I/ATLAS, come from outside our solar system entirely.
Short-period comets have orbital periods less than 200 years and come from the Kuiper Belt. They orbit in the same plane as the planets. Long-period comets have orbital periods over 200 years (some over millions of years), come from the Oort Cloud, and can approach from any direction.
The Oort Cloud extends from about 2,000 AU to 100,000 AU from the Sun (possibly even 200,000 AU). For reference, Neptune is only 30 AU away. Light takes about 1.5 years to reach the inner edge of the Oort Cloud, and over 1.5 years to reach its outer boundary.
An interstellar object is a body that originated from outside our solar system, traveling through interstellar space before 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.