Solar and Moon Eclipses

Introduction

Solar eclipses

A solar eclipse occurs when the shadow cone of the Moon intersects the surface of the Earth and is observable by anyone within this shadow zone

Two conditions have to be met for a solar eclipse to occur. The first concerns the relationship between the orbits of the Earth and the Moon, which are not in the same plane, but are inclined at around 5 degrees (5° 8' 43") to each other. The Moon crosses the plane of the Earth's orbit twice in each complete lunar orbit. For an eclipse to occur the Moon must be near one of these intersection points, called nodes. The second condition is that the Sun, the Earth and the Moon must also be lined up, corresponding to the phase of the New Moon.

pes of solar eclipses: annular, partial, total The Moon's shadow consists of two cone-shaped areas, known as the umbra (externally tangent to the Sun and Moon) and the penumbra (internally tangent to the Sun and Moon). For an observer standing between the Moon and the umbra cone summit the eclipse is total. If the observer is beyond the cone summit, the eclipse is annular (ring-like): the apparent diameter of the Moon is too small to mask the whole solar disk. For an observer standing in the penumbra, only a part of the Sun is masked: the eclipse is partial.

The most favourable conditions for a total eclipse are when the Moon is at its perigee, the Earth is farthest from the Sun (around July) and when the Sun is observed near zenith. When these conditions are all met, one can have a totality duration of more than 7 minutes

Moon eclipse

A lunar eclipse occurs when the Earth comes between the Sun and the Moon and the Earth's shadow passes over the Moon. This phenomenon can be seen by any observer on Earth for whom the Moon is above the horizon. Lunar eclipses occur at the time of a Full Moon, but not every Full Moon, because the Moon has to be near one of the nodes of intersection between its orbit and the ecliptic plane.

The Earth umbra is larger than the whole Moon. So, one will observe either a total eclipse by the umbra (which can be well observed), a partial eclipse by the umbra and penumbra, or a total or partial eclipse by the penumbra only, depending on where the centre of the earth's shadow is with respect to the disk of the Moon. The duration of a lunar eclipse is much longer than a solar eclipse, and can take as much as six hours.

In practice, the lunar eclipse conditions are modified due to the refraction of the Sun's rays by the Earth's atmosphere. This refraction (of 35 minutes of arc) allows some light to penetrate the cone of the geometric umbra. So even during total lunar eclipse, the lunar disk is not completely dark. This grazing light is more absorbed by the Earth's atmosphere in the blue and yellow portions of the spectrum, giving a particular reddish light during total lunar eclipse.

2018

31.Jan Lunar Eclipse Total North/East Europe, Asia, Australia, North/East Africa, North America, North/West South America, Pacific, Atlantic, Indian Ocean, Arctic, Antarctica
15. Feb Solar Eclipse Partial South in South America, Pacific, Atlantic, Antarctica
13. Jul Solar Eclipse Partial South in Australia, Pacific, Indian Ocean
27/28. Jul Lunar Eclipse Total Much of Europe, Much of Asia, Australia, Africa, South in North America, South America, Pacific, Atlantic, Indian Ocean, Antarctica
11. Aug Solar Eclipse Partial North/East Europe, North/West Asia, North in North America, Atlantic, Arctic

2019

5/6. Jan Solar Eclipse Partial East in Asia, Pacific
20/21. Jan Lunar Eclipse Total Europe, Asia, Africa, North America, South America, Pacific, Atlantic, Indian Ocean, Arctic
2. Jul Solar Eclipse Total South in North America, Much of South America, Pacific
16/17. Jul Moon Eclipse Partial Much of Europe, Much of Asia, Australia, Africa, South/East North America, South America, Pacific, Atlantic, Indian Ocean, Antarctica
16/17. Jul Moon Eclipse Partial Much of Europe, Much of Asia, Australia, Africa, South/East North America, South America, Pacific, Atlantic, Indian Ocean, Antarctica
26. Dez Solar Eclipse Annular East in Europe, Much of Asia, North/West Australia, East in Africa, Pacific, Indian Ocean