The 365 Days of Astronomy Astronomy Cast Ep. 771: Comet Tails
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Nov 17, 2025 Dive into the mystical world of comets and their mesmerizing tails. Discover why tails exist, how they grow, and the captivating colors they can display. Learn about the unique phenomena of forward-facing plumes and how solar forces shape tail directions. Uncover the secrets behind comet dust, ion tails, and the fascinating role of spectroscopy in revealing their composition. Plus, explore the exciting potential of spacecraft encounters with these icy wanderers as they journey through the cosmos!
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What A Comet Tail Actually Is
- A comet tail is material removed from the nucleus by sublimation or other energetic processes.
- The coma is expanding gas and dust lofted from the nucleus and forms the visible tail when acted on by external forces.
Making A Classroom Comet
- Fraser described a hands-on comet demo using dry ice, cooking oil, dirt and ammonia at a public science event.
- The model showed sublimation lofting particles and shedding material from the surface.
Two Distinct Tail Mechanisms
- Comet tails split into an ion tail and a dust tail with different drivers.
- Ion tails are charged and follow magnetic/solar-wind forces while dust tails respond to momentum and photon pressure.