Observing basics
视宁度
Seeing
How much the atmosphere smears a star's image.
In poor seeing, anything past 200× is just a blur.
Related terms
- ZHR — The theoretical hourly rate of a shower under perfect skies.
- Sidereal day — One rotation relative to the stars, about 4 minutes short of a solar day.
- Solar eclipse — The Moon covering the Sun.
- Lunar eclipse — The Moon passing into Earth's shadow.