为什么彗星有尾巴？
Why do comets have tails?
彗核是冰掺尘埃，本身几乎不发光。靠近太阳时冰直接升华，气体带着尘埃溢出成彗发，再分两路：中性尘埃被太阳辐射压向外推、反射阳光，成宽而弯的尘埃尾；电离气体被太阳风及其磁场拖拽，成笔直背离太阳的离子尾，长可超过日地距离。但要注意尾的朝向由太阳定而非飞行方向，彗星离去时尾巴在它前头；那看着实心的光带也稀薄得挡不住背后的星。
A comet nucleus is ice mixed with dust and barely shines by itself. Nearing the sun the ice sublimates straight into gas, dust spilling out with it into a coma, then two forces sort the debris: radiation pressure pushes neutral dust outward and reflected sunlight makes the broad curved dust tail, while the solar wind and its magnetic field drag ionized gas into a straight ion tail pointing away from the sun, long enough to exceed the earth-sun distance. The sun, not the motion, sets that direction—an outbound comet has its tail ahead of it—and the seemingly solid band is too tenuous to hide the stars behind it.
难度 进阶 · 适合 小学高段(9-12)
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 #太阳风 #冰
哈雷彗星大约多久回归一次？
How often does Halley's Comet return?
哈雷彗星的轨道周期约 76 年，是人类最早确认周期性的彗星，下次预计在 2061 年回归。
Halley's Comet has an orbital period of about 76 years and was the first comet recognized as periodic; it is expected to return around 2061.
难度 入门 · 适合 幼儿(3-6)
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）
#彗星 #周期 #哈雷
彗尾为什么总是指向背离太阳的方向？
Why does a comet's tail always point away from the Sun?
太阳风（带电粒子流）和辐射压力把彗星的气体与尘埃吹向外侧，离子尾几乎笔直背向太阳，尘埃尾则略弯曲。
The solar wind and radiation pressure blow the comet's gas and dust outward; the ion tail points nearly straight away from the Sun while the dust tail curves slightly.
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）
#彗星 #太阳风 #彗尾
彗星由哪几部分组成？
What parts make up a comet?
彗星中心是冰与尘埃组成的彗核，靠近太阳时蒸发形成彗发和背向太阳的彗尾，常分为尘埃尾和离子尾。
A comet has an icy-dust nucleus; near the Sun it vaporizes to form a coma and a tail pointing away from the Sun, typically split into a dust tail and an ion tail.
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）
#彗星 #彗核 #彗尾