Small bodies

Comets

Ices, dust and long tails

Small bodies rich in ices can develop a coma and tails as they approach the Sun.

Educational illustration · shapes and sizes are not to scale.

Composition: Ices and dust
Examples: 1P/Halley · 67P/Churyumov–Gerasimenko

What makes this world interesting

Warming releases gas and dust. The tails are not a fixed trail behind the object’s motion: solar radiation and the solar wind shape them. Their brightness can change in ways that are difficult to predict.

Observe or explore it

Use recent ephemerides. An integrated magnitude does not guarantee the visibility of a diffuse object; a dark sky matters greatly.

Connect the discoveries

The Kuiper Belt The Oort Cloud Meteoroids, meteors and meteorites

Sources and reference information

NASA Science — Comets

Rounded educational data, sources consulted on 18 October 2026. Orbital distances are mean reference distances from the Sun, not current distances from Earth. Periods are expressed in Earth time. The planner provides date-specific positions for supported targets.