EclipseGeeks - Solar Eclipses and Lunar Eclipses


All you ever wanted to know about eclipses and other celstial bodies

A Total Lunar Eclipse occurs at night with the Moon entering Earth's shadow, firstly into the penumbra (Earth's outer shadow) where only some of the light is blocked from reaching the Moon - turning the Moon from its familiar white to a subtle shade of white-grey. This phase is rather difficult to detect by the human eye, and may go un-noticed.


However, when the Moon begins to enter Earth's umbra shadow, the Full Moon will begin the turn black and it will look like a chunk has been cut from the Moon. It is very noticeable and easy to see. As the Moon progresses further into the umbra, the Moon will seem to disappear and resmble a quarter Moon. Soon after this phase the Earth begins to prevent almost all of the Sun's light reaching the surface of the Moon, and Moon is completely

The reason the Moon turns red during a Total Lunar Eclipse


Deep in Earth's umbra during the Moon's phase of Totality one would expect the Full Moon to disappear from sight but this does not happen, instead it glows copper red, brown, crimson red, or orange.


The reason is that although the Moon is in Earth's umbra, light is scattered and refracted from Earth's atmosphere.


When sunlight strikes Earth, the atmosphere of Earth filters out most of the blue light and it is scattered, which is why the sky is blue. The remaining light is of orange to deep red, and is much dimmer than pure white sunlight. Earth's atmosphere then refracts (bends) some of this red light towards the Moon, and so is illuminated a reddish tone.


In addition, the amount of colour change is affected by particles in Earth's atmosphere such as dust floating around in the very air we breathe, fine particles from recent volcanic activity, water vapour, pollutants and a myriad of other particles in the atmosphere. All this contributes to the apparent colour of the Moon and helps make a Lunar Eclipse so magical to observe. If volcanic activity has been recent the Moon will often appear even redder than a normal lunar eclipse.

partial penumbra eclipse

In principle a Penumbra Lunar Eclipse can be either a partial penumbra eclipse or a total penumbra eclipse. The vast majority of penumbra eclipses are partial with the Moon passing through part of the penumbra while a portion of the Moon remains outside in normal sunlight.


Most penumbra eclipses are uninteresting since the Moon is still quite brightly illuminated. At maximum eclipse sharp eyed viewers may see a subtle shading across the Moon but it is difficult to see, even when using a telescope and it also very much depends on how much the Moon is inside the penumbra shadow. The deeper inside the penumbra the more chance one has of spotting the subtle changes of tone and illumination.


The diagram on the left shows the Moon passing quite deeply through the penumbra. A penumbra eclipse such as this would appear darker in the northern regions while the south would still be in sunlight and therefore appear brighter

It would be pretty amazing and make a breath-taking sight to view the eclipse from the Moon's own surface watching the Earth being eclipsed.  Although the Earth would completely cover the Sun, it would be surrounded by a halo of an orange tinged ring and glow like millions of glittering diamonds, You would simultaneously be watching every sunset and sunrise occurring at the same time on planet earth.  


Earth's atmosphere glowing bright orange and the sudden drop of temperature on the Moon’s surface from maximum 133C to minimum -233C in an instant, the surface under your feet changing colour to crimson red.  It would be a glorious sight.


I had the ambition to not only go farther than any man had gone before, but to go as far as it was possible to go - Captain Cook, 1728 - 1779

Forth classification called a Total Penumbral Lunar Eclipse.


This is when the Moon passes completely within the penumbra, without any section passing through the inner umbra.


These types of lunar eclipses are rather rare. From 1901 to 2000 there were only 9 Total Penumbral Lunar Eclipses, and between 2001 to 2100 there will be only 5 such lunar eclipses.


Their rarity doesn’t mean they are anything extravagant to watch, they are not that noticeable, and when the Moon passes completely through the penumbra, it dims slightly, and many people wouldn’t really notice much difference in brightness.    


Geometry of a Total Lunar Eclipse

Total Lunar Eclipse physical attributes (diagram 1)


A Total Eclipse of the Moon, or Total Lunar Eclipse is when the Sun, the Earth and the Moon are in perfect or very near perfect alignment.


Earth is between the Sun and the Moon.  The Moon is a Full Moon and is at one of its nodes.


The Moon passes behind Earth and becomes completely immersed in Earth’s umbra shadow.

Geometry of Lunar Eclipses

The Various Types of Lunar Eclipse


There are three main types of Lunar Eclipse, they are; penumbra, partial, and Total.

There is also a forth sub-classification called, a Total Penumbral Lunar Eclipse (This type of lunar eclipse is relatively rare)

various types of lunar eclipse: reasons why and how lunar eclipses occur:


Everything you need to know about an eclipse of the Moon is here:

An Eclipse of the Moon can be: a Total Eclipse; a partail eclipse, or penumbra eclipse.

The multi-exposure image shows the changing shades of the Moon as it passes trhough Eath's shadow. Compare them with the diagram on the far left, showing the Moon's postion in its various stages through Earth's penumbra and umbra through .



A lunar eclipse needs three physical requirements.


(1) The Moon must be a Full Moon.

(2) The Moon must be at or near one of its nodes.

(3) The Sun, the Earth, and the Moon must be in perfect or very near perfect alignment.

Below are dagrams showing the position of the Moon during a Lunar Eclipse


Below are various diagrams showing the position of the Moon, the Earth, and the Sun during an eclipse of the Moon;

plus explanations describing the lunar nodes.


Examples of a Total Lunar Eclipse


What is an eclipse?  

Eclipse Definition:


An eclipse is the total or partial obscuring of one celestial body by another. It may occur when one celestial body passes in front of another therefore cutting off some or all of its light. It may also occur when a celestial body passes through all or part off the shadow of another celestial body.

What is a Lunar Eclipse, or Eclipse of the Moon?


A lunar eclipse occurs when the Moon passes through Earth's shadow.  


A lunar eclipse only occurs when the Sun, the Moon, and the Earth are in perfect or very near perfect alignment, and the Full Mooon is at or near one of its nodes.

click above to enlarge diagram of eclipse.

When observing a Total Lunar eclipse you are watching the Day Side of the Moon. As the Moon enters the umbra it begins to

change colour from a bright Full Moon to one of varying colours of brown - orange - red. A Lunar Eclipse is visible to everyone

with a clear view of the Moon on Earth's night-time side. A Lunar Eclipse can last for several hours from first contact with the

penumbra to last contact with the penumbra. The length of totality can range from around 20 to approximately 100 minutes.



A photograph of a rare Total Penumbra Lunar Eclipse showing the slight variation of brightness. The two images of the Moon side-by-side make it fairly easy to see the slight tone change. However observing a total penumbra lunar eclipse, even with a telescope can be difficult to see due to such slight differences in appearence.

Nodes of the Moon:

points at which the Moon crosses the ecliptic plane


The Moon must be crossing the ecliptic plane within 11° 38´ longitude, either travelling south or northwards, so that the Sun, Earth, and the Moon are in perfect or near perfect alignment.


Diagram;  Nodes of the Moon as it crosses the ecliptic plane


Diagram of a Total Lunar Eclipse

showing the relative positions of the Sun, Earth and the Moon




Lucien Rudaux - French astronomer and artist  (1874 – 1947) who created famous paintings of space themes of  the 1920s and 1930s.


Title of painting: Lunar Eclipse as seen from the Moon


A Total Lunar Eclipse as seen from the Moon.


This is an artists impression of a total lunar eclipse as seen from the surface o fthe Moon. It was quite a feat painting such amn accurate account of how a total lunar eclipse look from the Moon, considering the age in which he imagined and created the art piece. h ba l


Lucien Rudaux was, first and foremost, an astronomer and became director of the observatory at Donville, Normandy. He also wrote and illustrated his own books, such as the sought-after classic Sur les autres mondes.


Total Penumbra Eclipse

A Rare Total Penumbra Lunar Eclipse


The diagram shows the position of the Moon as it passes through Earth's outer fainter penumbra shadow.


A Total Penumbra Eclipse is when the whole of the Moon passes within the penumbra shadow. A Total Penumbra Eclipse is rare because the penumbra shadow cast by Earth is about as wide as the Moon itself. About 1.2% of all lunar eclipses are Total Penumbra Eclipses.

Eclipse of the Moon

position the Moon through Earth's umbra and penumbra during a Total Lunar Eclipse


Total Lunar Eclipse requirments.


The example diagram shows the Moon passing through Earth’s shadows. The outer fainter shadow is  called, the penumbra, and the deep inner shadow is called the umbra.  


In the diagram the Moon is passing completely immersed in the shadow of Earth’s umbra, and therefor is a Total Lunar Eclipse. A Total Lunar Eclipse is visible to the entire night-side of Earth.  


click idiagram nodes of Moon to enlarge

Geometry of a Lunar Eclipse

Information about Lunar Eclipses


Why the Moon turns red during a Total lunar Eclipse

As easy as chips:

A Lunar Eclipse


The Nodes of the Moon explained.


Phases of the Moon

We have all observed the various phases of the Moon as it orbits Earth. As viewed from the surface of Earth, it takes 29.53059 days (29d 12h 44m 03s) for the Moon to complete one orbit of Earth. This orbit of the Moon is called the Synodic Month and it is the well- known cycle that governs our Moon Phases.


Eclipse of the Moon

If the Moon orbited Earth in the same plane as the ecliptic, there would be an Eclipse of the Moon every month, followed two weeks later by a Solar Eclipse, but the Moon does not orbit Earth along the ecliptic plane, instead it orbits Earth at an inclined angle.


The Moon's inclined orbit around Earth

The Moon orbits Earth at an angle of 5.16 degrees. This means that as it takes approximately 29 days for the Moon to complete 1 orbit of Earth it must cross the ecliptic plane twice in that time.


Moon Nodes

The point at which the Moon intersects the ecliptic plane is called a node. The Moon can pass either southwards or northward through the ecliptic plane; hence, one of its nodes.


If the Moon is going from south to north in its orbit, it is called an ascending node. If the Moon is going from north to south, it is called a descending node.


Eclipse Window is within 11.38 degrees longitude of the ecliptic plane:

If a Full Moon or New Moon is within 11.38 degrees longitude of the ecliptic plane then there will be an eclipse. A Full Moon meeting these specifications will produce a lunar eclipse, while a New Moon meeting these requirements will produce a solar eclipse.

Moon-photo-image-Total-Lunar-Eclipse-Geeks Moon-image-photo-Total-Lunar-Eclipse-Geeks

To enlarge: Click diagram of penumbra / umbra.