| Our planet's shadow has two parts, a dark inner core called the umbra and a pale outer fringe called the penumbra. |
| But the penumbra is so faint that it cannot be recognized until just before the Moon enters the Earth's dark central shadow, the umbra. |
| Long, thin filaments radiate from the umbra into a brighter surrounding region called the penumbra. |
| Outlined against the setting sun, the silhouette took on a strangely surreal beauty, as if a shadow's penumbra and umbra were fused together. |
| He stands within the penumbra of the falls, near the top of Irish Mountain. |
| How much the moon is dimmed depends on whether it passed through the penumbra or the darkest part of the shadow, the umbra. |
