ECLIPSES OF MOON
Data from Wikipedia and NASA (C)
A lunar eclipse happens when the Moon passes in the cone of shadow of the Earth and in such a way it darks totally or partially. This situation can only happen in the phase of full Moon, when the Moon and the Earth are in conjunction as seen from the Sun. The penumbral cone is external to that one of shadow, and much more is extended than this last one.
TYPE OF ECLIPSES
Exist 4 type of lunar eclipses :
Total, happens when the Moon is completely darkened from the earth shadow. The disc of the Moon passes totally in our cone of shadow, with a consequent strongly decrease of brightness; sometimes the phenomenon is therefore "deep" that the lunar disc disappear totally to our vision. Other times assume a red color.
Partial, it happens when the Moon passes only partially in the cone of totality shadow. The brightness decrease is inversely proportional to the distance of the Moon from the center of the earth shadow.
Penumbral, happens when the Moon passes in the cone of penumbra of the Earth; our planet blocks only a small part of the sunlight and therefore our satellite appears still very illuminated; this type of eclipse is very little visible to naked eye in how much the brightness case is minimal.
Partial penumbral: also the lunar eclipses of penumbra can be partial; that happens when the Moon does not enter totally in the earth penumbra.
The lunar cycle is approximately 29,5 days, therefore the Moon returns in "the full" phase nearly every month. But why the Moon eclipses are not never repeated then with the same frequency? The answer is in the lunar orbit, that it is tilted of beyond 5° regarding the earth orbit. This inclination makes yes that not always Moon Earth and Sun are aligned, in order the Moon must pass in the so-called ascending node or the descendant of its orbit. That only happens from 2 to 4 times to the year. The Moon eclipses, with the exception of those solar ones, are visible from the entire earth hemisphere that is not turned towards the Sun. Of all the eclipses that happen 35% are of penumbral type, 30% are partial and remaining 35% total. Although during the total eclipses the Earth blocks the sunlight, a small part of it filters and illuminates our satellite of a red-orange-yellow in how much only the red frequencies of the light pass from our atmosphere. To this light sum the light reflected from our same planet.
All the total eclipses begin with a penumbral phase followed from a partial phase whose durations depend on how much the Moon pass near to the center of the earth shadows.
For the lunar observations they do not need filters of protection of the eyes of no type. Indeed, modest binoculars or telescope can offer exceptional shows.
Saying γ (gamma) the minimal distance from the center of the axis of the earth shadow to the center of the Moon, in unit of earth equatorial radius
· if γ > 0 the moon passes to north of the axis of the shadow
· if γ < 0 the moon passes to south of the axis of the shadow
Saying u the radius of the cone of shadow of the Earth in the fundamental plan
σ = 1.2848 + u it is the radius of the penumbra to the distance of the Moon
σ = 0.7403 + it is the radius of the umbra to the distance of the Moon
In the case of penumbral eclipses the maximum magnitude in the place of better visibility on the Earth, that it is more close to the axis of the shadow is
while for the shadow it is
SEVERAL DATA ON THE SUN ECLIPSES
All the data that follow are based on the French Rule of Connaissance des Temps of Paris.
number of lunar eclipses in a year varied from 2 to 5. There will be
eclipses of shadow (and from in ahead we will define here as shadow eclipse is
those totals that those partial ones) can be 0,1,2 or
3. From 1500 to 2499 there are 191 years with 0 eclipses of shadow, 105 with 1,
676 with 2 and 28 with 3. The next event with
4 successive eclipses can be all totals.
In period 0-2999 there will be 7249 moon eclipses, of which 2089 totals, 2536 partial and 2620 penumbral.
maximum magnitude in shadow for this century is 1,88 on
Sometimes there aren’t total eclipse for 3 consecutive years, the next cycle will be in 2160-61-62.
Don exist 2 consecutive years with only penumbral eclipses.
The extreme diameters of the Moon are 1763" at apogee and 2012" at the perigee. The radius of earth penumbra varied 1888"to 1952".
of penumbra, in the period
The magnitude of the total eclipses varied from 1,001 to 1,094.
eclipse the Moon can also hide stars. Such events are rare in the case of luminous:
Regulus will come hidden during the total eclipse on
Also the planets can be hidden during a eclipse:
the total of
in the partial on
in the total on
in the total on
of an eclipse: in period
consider also the phase of partiality the duration it can arrive nearly to 4
hours. The longest on
the phase of penumbra the duration arrives to 379.11 minutes on
4 consecutive total eclipses, in period
Every how much happens the eclipses of Moon shadow? Every 5, 6, 11, 12, 17 or 23 lunations.