What is a lunar eclipse?
A lunar eclipse occurs when the moon passes through the earth's shadow. As we can see in the illustration below, the earth has a dark shadow, i.e. The umbra, and a less dark shadow known as the penumbra. These two shadows create three different types of lunar eclipses.
A total lunar eclipse occurs when the entire moon passes into the earth's umbral shadow. On the other hand, an umbral eclipse occurs when any part of the moon passes through the earth's umbral shadow. Finally, a penumbral eclipse occurs when the moon passes only through the penumbral shadow without entering the umbral shadow.
Eclipse Contact times
The contacts that the moon makes with the earth's shadow define the beginning and end of each eclipse phase. All lunar eclipses have P1 and P4 phases. P1 is the first external contact of the moon with the earth's penumbral shadow and P4 is the final external contact with the earth's shadow. The phase between the P1 and P4 contacts is the penumbral phase. The internal contacts with the earth's penumbral shadow, P2 and P3 are usually not of interest. Since the penumbral shadow is not very dark, these contacts are nearly impossible to observe. In fact, a penumbral eclipse in which less than 60 percent of the moon's diameter enters the penumbra is almost impossible to see even with a telescope.
In addition, the contact points associated with the umbra also have designations. U1 and U4 are the first and last external contacts of the moon and the umbral shadow, while U2 and U3 are the internal contacts with the umbra. The U2 and U3 phases are only present during total lunar eclipses. In fact, all 6 of the contact times, P1, U1, U2, U3, U4, and P4 are relevant for total lunar eclipses.
Lunar Eclipses Classified
The illustration above shows the progress of the three types of eclipses.
Penumbral Eclipses
The red path shows the progression of a penumbral eclipse. The eclipse begins when the moon first touches the edge of the penumbra (P1) and ends when the moon fully exits the earth's penumbra (P4). The gap between the umbra and the penumbra is a little larger than the diameter of the moon. As a result, a "total penumbral eclipse" in which the moon is completely within the penumbral shadow without entering the umbral shadow is possible. According to Fred Espenak, a noted eclipse expert, about 36% of all lunar eclipses are penumbral eclipses. Only about 3% of all penumbral eclipses are "total penumbral eclipses.
Partial Lunar (Umbral) Eclipses
In contrast, the green path shows the progress of a partial lunar eclipse. Contacts P1 and P4 are present. In addition, contact U1 marks the first contact of the moon with the umbra, and contact U4 marks the time of exit of the moon from the umbra. During a partial eclipse, at no time does the moon fully enter the umbra. As a result, there are no U2 or U3 contacts associated with a partial lunar eclipse., About 35% of all lunar eclipses are partial eclipses.
Total Lunar Eclipses
A Total lunar eclipse occurs when the moon is fully within the earth's umbra. ., About 29% of all lunar eclipses are total lunar eclipses.
The blue path shows the progress of a total lunar eclipse. The U2 contact is the first point in the eclipse in which the moon is completely inside the umbra. On the other hand, the U3 contact is the last moment when the moon is totally within the umbra. Accordingly, the time period between U2 and U3 represents the duration of the totality phase of a total lunar eclipse. All total lunar eclipses have penumbral and umbral phases before and after the totality phase.
List of upcoming eclipses
| Date | Type |
|---|---|
| July 5, 2020 | Penumbral Eclipse" |
| May 26, 2021 | Total Lunar Eclipse" |
| November 19, 2021 | Umbral Eclipse" |
| May 16, 2022 | Total Lunar Eclipse" |
| November 8, 2022 | Total Lunar Eclipse" |
| May 5, 2023 | Penumbral Eclipse" |
| October 28, 2023 | Umbral Eclipse" |
| March 25, 2024 | Penumbral Eclipse" |
| September 18, 2024 | Umbral Eclipse" |
| March 14, 2025 | Total Lunar Eclipse" |
| September 7, 2025 | Total Lunar Eclipse" |
| March 3, 2026 | Total Lunar Eclipse" |
| August 28, 2026 | Umbral Eclipse" |
| February 20, 2027 | Penumbral Eclipse" |
| August 17, 2027 | Penumbral Eclipse" |
| January 12, 2028 | Umbral Eclipse" |
| July 6, 2028 | Umbral Eclipse" |
| December 31, 2028 | Total Lunar Eclipse" |
| June 26, 2029 | Total Lunar Eclipse" |
| December 20, 2029 | Total Lunar Eclipse" |
| June 15, 2030 | Umbral Eclipse" |