Explanation of Penumbral Contacts and Extremes for Solar Eclipses
by Fred Espenak
The following tables contain brief explanations for the various contact times of the Moon’s penumbral shadow with Earth’s surface during an eclipse of the Sun.
| Contacts of Penumbral Shadow with Earth | ||
| Contact Event | Contact | Description |
| First External Contact | P1 | Instant of first external tangency of the penumbral shadow cone with Earth’s surface
(edge of penumbral shadow first falls on Earth - partial eclipse begins) |
| First Internal Contact | P2 | Instant of first internal tangency of the penumbral shadow cone with Earth’s surface
(entire penumbral shadow first falls on Earth) |
| Last Internal Contact | P3 | Instant of last internal tangency of the penumbral shadow cone with Earth’s surface
(entire penumbral shadow last falls on Earth) |
| Last External Contact | P4 | Instant of last external tangency of the penumbral shadow cone with Earth’s surface
(edge of penumbral shadow last falls on Earth - partial eclipse ends) |
| Extreme Northern and Southern Path Limits of Penumbra | ||
| Contact Event | Contact | Description |
| North Extreme Path Limit 1 | N1 | Northern limit of the penumbral shadow at the start of the penumbral path |
| South Extreme Path Limit 1 | S1 | Southern limit of the penumbral shadow at the start of the penumbral path |
| North Extreme Path Limit 2 | N2 | Northern limit of the penumbral shadow at the end of the penumbral path |
| South Extreme Path Limit 2 | S2 | Southern limit of the penumbral shadow at the end of the penumbral path |
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