Solar eclipse
An earthly solar eclipse or eclipse ( ancient Greek ἔκλειψις ékleipsis "overlay, cover, extinction") is an astronomical event in which the sun is partially or completely covered by the moon as seen from the earth . The shadow of the moon strokes the earth, which is only possible with a new moon .
The sun and moon appear to an observer on earth with approximately the same apparent diameter (average 0.52 °), which is why the moon can sometimes completely cover the solar disk . The trace of the umbra of the moon falling on the earth during such a total solar eclipse is, however, at most a few hundred kilometers wide. The penumbra of the moon, on the other hand, measures several thousand kilometers, due to the planar light source of the sun, a transition shadow with a smooth transition in brightness, so that a partial eclipse of the sun can then be observed from more than a quarter of the earth's surface .
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history
Cuneiform writings show that the Babylonians from around 800 BC Eclipse cycles with the Saros period (around 18 years) were already known. This astonishing research was motivated, among other things, by the fact that solar eclipses in antiquity and up to the early modern period were considered to be disastrous signs of divine powers.
The anecdote handed down by Herodotus is known , according to which Thales of Miletus predicted a solar eclipse during a war between the Medes and the Lydians . When this actually occurred, the opponents had ended the fight in fright and made peace. It could be the solar eclipse of May 28, 585 BC. Act, but some arguments also speak in favor of the solar eclipse of March 16, 581 BC. Chr. More reports of eclipses of antiquity lie v especially before a solar eclipse in August 310th BC, which was observed by the fleet of Agathocles on their campaign against Carthage , as well as for an eclipse in April 136 BC. BC, which was observed in Mesopotamia . Corresponding eclipse observations have also been handed down from China . To what extent ancient astronomers were actually able to predict solar eclipses is a matter of dispute in research; What is certain, however, is that the Babylonian astronomers were already familiar with the Saros period . The antique mechanism of Antikythera , a structure of gears probably from the 2nd or 1st century BC. BC, can be viewed as a calendar which, using analogue calculations , also allowed the prediction of solar and lunar eclipses , among other things .
The approximately three-hour eclipse at the crucifixion of Jesus Christ , which is reported in the Bible in the New Testament , cannot have been a solar eclipse in the sense discussed here. For all four Gospels agree that Jesus was crucified on the 14th or 15th of the Jewish month of Nisan ; A solar eclipse is impossible on this date, since in the Jewish calendar there was a full moon around the middle of the month, not the new moon required for a solar eclipse. In contrast, the Bible describes that in the Old Testament - when the Jews left Egypt - a solar eclipse must have played an important role.
The scientific treatment of solar eclipses, which began in antiquity, only came back into the field of vision of researchers with the establishment of the heliocentric worldview by Copernicus and Kepler . Erhard Weigel made a detailed forecast of the solar eclipse on August 2nd July 1654 . / August 12, 1654 greg. in front. Edmond Halley predicted the total solar eclipse of May 3, 1715 and also gave the course of the totality zone in Great Britain . With his knowledge of the orbital motion of the sun and moon, he also tried to research eclipses in the past. He encountered unexpected contradictions - total solar eclipses that had actually been observed in the eastern Mediterranean should, according to Halley's calculations, have taken place in Spain. This contradiction could ultimately be explained by an increasing slowing down of the earth's revolutions : the day length increases by an average of around 17 microseconds per year. This effect adds up over the centuries, so that it has to be taken into account when calculating historical eclipses.
Since the middle of the 19th century, the astronomical societies of some industrialized nations began to organize expeditions to more distant parts of the world to observe solar eclipses. The main focus of interest was the observation of the corona. The total solar eclipse of May 29, 1919 , as it was observed on the African island of Príncipe by an expedition led by Arthur Stanley Eddington , attracted special attention in connection with the theory of relativity developed by Albert Einstein a few years earlier , which, among other things, included distraction of the light of distant stars through the gravitational field of the sun - which was confirmed by the observations.
The mention of a solar eclipse in ancient texts can provide important chronological fixed points. So is the solar eclipse of June 15, 763 BC. . BC in the Assyrian Eponymenliste of Bur-Saggile (governor of Guzana listed), which allows to anchor this list in our calendar.
Basics of a solar eclipse
For a solar eclipse to occur, the sun, moon and earth must be on a line. Since the lunar orbit is inclined towards the ecliptic plane (by about 5 °), this does not occur every time at a new moon , but only when the moon is then near one of the two intersections of the lunar orbit and the ecliptic plane. It takes half an eclipse year (173.31 days) until one of these two lunar nodes passes the sun again .
In the case of many central eclipses - when the center of the lunar disc moves over the center of the sun - the apparent diameter of the moon can be sufficient to completely cover the sun, so that a total solar eclipse can be observed. But sometimes the moon disk is then too small relative to the sun disk, so that the sun remains visible around the moon as a ring-shaped solar eclipse . Because the distances from the sun and moon to the earth can form different relationships, since the orbit of the earth around the sun and that of the moon around the earth is not circular, but slightly elliptical .
If the umbra of the moon does not pass over an observer or a place on earth, but its penumbra, then we speak of a partial solar eclipse . In regional terms, this can be observed more frequently than a total solar eclipse, because the trace of the umbra on the earth's surface is not wide, at most less than 300 km near the equator.
Since the sun, moon and earth are not point-like structures, solar eclipses can also take place at a certain distance from the lunar node, the so-called eclipse limit ; Measured as an ecliptical angle on both sides, this area is just under 17 ° for eclipses that can arise from the moon's penumbra, which is cast in relation to the earth as a whole. Occasionally - alternating one series of the semester cycle from 8 to 10 half years to the next - the next solar eclipse can occur about a month later after a partial solar eclipse. The eclipse range for total solar eclipses, however, only has a node distance of around ± 10.6 ° or is around 22 days; a total lunation (on average 29.53 days) cannot be followed by a total eclipse of the sun, but a lunar eclipse after about half a lunation . In every calendar year there are at least 2, but a maximum of 5 solar eclipses.
Types of solar eclipses
In relation to the earth as a whole and its position in space, solar eclipses are differentiated according to the position of the axis of the moon's shadow, into central ones, where it passes through the earth, and partial solar eclipses where the axis of the shadow passes the earth.
An eclipse in which the earth is only reached by the penumbra of the moon is called a partial solar eclipse in this sense . Such eclipses occur in areas near the two poles of the earth.
Eclipses in which the axis of the moon's shadow crosses the earth are called central eclipses . These are total , ring-shaped and hybrid as three forms differentiated according to whether and how the conical umbra reaches the earth's surface.
As a special case, non-central total or ring-shaped eclipses can occur, in which the axis of the moon's shadow just misses the earth, but parts of the earth's surface can experience totality or eccentric annularity.
Total solar eclipse
In a total solar eclipse, the apparent diameter of the moon is larger than that of the sun. The observation of such an eclipse is of particular interest because one can also observe the solar corona , which is otherwise outshone by the bright light of the sun. For solar physicist consists opportunity to study the solar corona.
Since the apparent diameter of the moon, even in the most favorable constellation, only marginally exceeds that of the sun, the totality zone is max. 273 km relatively narrow. The duration of totality in a place is determined not only by the proportions between the sun and the moon, but also by the orbital speed of the moon and the speed of the earth's rotation. The totality tends to last the longest in the area of the equator , since this is where the earth's surface follows the advancing moon shadow the fastest and also has a shorter distance to the moon, which means that the umbra tends to be larger. The longest total solar eclipse between 1999 BC. And 3,000 AD takes place at 7:29 minutes on July 16, 2186.
Annular solar eclipse
If, due to the elliptical orbits of the earth around the sun and the moon around the earth, the apparent diameter of the sun exceeds that of the moon, the outer edge of the sun remains visible during an eclipse. It is therefore also called a ring-shaped , annular or wreath of fire solar eclipse . The umbra of the moon does not reach the surface of the earth. A solar corona is then not recognizable because it is outshone by the part of the sun that remains visible.
A circular phase can last longer than a full phase. This is because the moon disk, which is smaller in a ring-shaped eclipse, has to travel a longer distance before it is past the sun disk. In addition, the orbital speed of the moon is lower because of its greater distance from the earth (2nd Kepler's law) . Theoretically, the annular phase can currently reach about 12.5 minutes.
Hybrid solar eclipse
At the beginning and / or end of a hybrid solar eclipse - also known as a ring-shaped total eclipse - the umbra of the moon does not extend to the surface of the earth; but because of its spherical shape, it meets it in the middle of its track. A hybrid solar eclipse begins and ends (mostly) as a ring-shaped eclipse, in between it is total. At the point of transition, both phases can each be observed for a tiny moment. The totality lasts only very briefly.
This form of solar eclipse is rare and only accounts for about 1% of all cases in the long-term compilations. An example is the eclipse of April 8, 2005 . At its maximum, the totality zone in the eastern Pacific off Costa Rica and Panama was only 27 kilometers wide, the totality duration was only 42 seconds. The last such eclipse took place on November 3, 2013 .
Partial solar eclipse
Most observers of a central eclipse are to the side outside of the central strip. The much wider side strips are only in the partial shade of the moon and observers only see a partially eclipsed sun. The observers of a total solar eclipse in the central strip also experience only the penumbra for a long time before and after the totality. Conceptually, the partial eclipse related to the earth must be distinguished from an observation of a partially eclipsed sun related to location and time in certain regions.
The decrease in brightness caused by a partial eclipse of the sun is only clearly perceptible when the degree of coverage is very high.
In an astronomical canon of solar eclipses, only partial solar eclipses that occur in the polar regions of the earth are referred to as such.
Non-central total or annular solar eclipse
If the axis of the moon's shadow misses the earth very closely, so that in a total eclipse parts of the moon's shadow reach the earth's surface, or in a ring-shaped eclipse the entire moon can be seen within the solar disk, but not centered anywhere, one speaks of a non-central total or annular solar eclipse. Such eclipses are rare - they only make up 1.3% of all eclipses. Like partial eclipses, they only occur near the earth's poles. The only non-central total eclipse in the 21st century is the solar eclipse of April 9, 2043 .
Characteristics of a solar eclipse
The quantitative labeling is particularly pronounced in the case of central eclipses. Several different parameters are used for this purpose.
contacts
In addition to the moment of maximum , every solar eclipse has four other characteristic moments, the four contacts, at every observation location .
- Contact: The new moon touches the solar disk for the first time. The partial phase begins.
- Contact: The new moon completely covers the solar disk (total eclipse) or is completely in front of the solar disk (annular eclipse). The total or ring-shaped phase begins.
- Contact: The new moon releases parts of the sun disk again (total darkness) or is no longer completely in front of the sun disk (ring-shaped darkness). It is switched back to the partial phase.
- Contact: The new moon touches the sun disk for the last time, after which the eclipse is over.
The time of each contact is given in the relevant tables. Often the direction of the relative movement between the moon and the sun, for example with respect to the horizon , is noted. For the moment of the maximum, the elevation angle of the sun is also given.
Degree of coverage and size
For both the partial and the various total phases, the extent of the eclipse can be described by the degree of coverage or by the size . This also applies to "pure" partial eclipses.
- The degree of coverage is the ratio between the area covered by the moon and the total area of the solar disk; it is stated in percent. In the case of total eclipse, the degree of coverage reaches the maximum of 100% everywhere within the totality zone; in the case of a ring-shaped eclipse, the value remains below 100%.
- According to the usual definition of a partial eclipse, the size (also called magnitude ) is the proportion of the sun's diameter covered by the moon (value less than 1). In the case of a total or a ring-shaped eclipse, the size is the ratio between the diameter of the moon and the diameter of the sun . The value is slightly larger than 1 (total) or slightly smaller than 1 (ring-shaped). An alternative definition named in the main article Size of a solar eclipse is uniform, i.e. it can be used for all types of eclipses.
During the course of an eclipse, the degree of coverage and size slowly increase, reach maximum values and then decrease again. In addition to the general maximum values, the relevant tables also specify the maximum values that can be achieved at an observation site.
Gamma value
The gamma value (symbol: γ ) is in an eclipse the smallest distance of the shadow of the moon axis from the center of the earth in terms of the equatorial radius is thus becomes approximately specified, in which. Latitudes of the Earth extends the central line.
The value is negative if the shadow axis passes south of the center of the earth. For | γ | <0.9972 there is a central line on the earth's surface where the eclipse is central (total or ring-shaped). Partial solar eclipses occur up to | γ | = 1.55.
Place and type of darkness
For example, the following table shows all solar eclipses between April 2311 and March 2315. Nine (−4 to +4) eclipses occurring over a period of about four years form the natural semester cycle. They follow each other in about 177 days (six lunations ). A graphic (right) is arranged next to the table for the middle of these nine eclipses.
| No. | width | Type |
date | Type |
width | gamma | size |
|---|---|---|---|---|---|---|---|
| −4 | April 19, 2311 | P | 71 ° N | 1.41 | 0.25 | ||
| v e1 | 69 ° S | P | May 19, 2311 | ||||
| −3 | October 13, 2311 | P | 72 ° S | −1.38 | 0.30 | ||
| v e2 | 70 ° N | P | November 11, 2311 | ||||
| −2 | April 7, 2312 | A. | 51 ° N | 0.72 | 0.93 | ||
| −1 | October 1, 2312 | T | 44 ° S | −0.68 | 1.06 | ||
| 0 | March 27, 2313 | A. | 2.6 ° N | −0.001 | 0.95 | ||
| 1 | September 21, 2313 | T | 3.0 ° N | 0.04 | 1.02 | ||
| 2 | March 17, 2314 | A. | 55 ° S | −0.72 | 0.99 | ||
| 3 | September 10, 2314 | A. | 57 ° N | 0.82 | 0.97 | ||
| n a | 70 ° N | P | February 5, 2315 | ||||
| 4th | March 6, 2315 | P | 72 ° S | −1.37 | 0.32 |
The celestial images of such an eclipse series are contained in the graphic below, relative to each other and relative to the two lunar nodes drawn on top of each other . The middle eclipse (theoretically) takes place exactly in the (descending) node: Gamma = 0. If, in addition, there is equality of day and night, its maximum is on the equator . The following (+) or preceding (-) eclipses alternately follow; respectively before; the node passage takes place. The greater the nodal distance , the greater their distance from the equator. At first they appear as central eclipses (1 and 2). If the lunar parallax or the eclipse limit for central eclipses is exceeded, there are only partial eclipses (3 and 4) that can be observed from the polar caps. Then the eclipse limit for partial eclipses is exceeded and the semester cycle ends. Before its end, however, the next cycle had already started on the other side of the node (n a ), and the previous cycle did not end until it started (v e ).
Deviations between the table and the graphic are "natural", because such a generally valid graphic can only be created with mean values of the underlying scattering astronomical quantities.
Local course of an eclipse
When calculating an eclipse, it is essentially about determining the global visibility areas and sizes of the eclipse as well as the local contact times, taking into account the apparent sizes of the sun and moon. Primarily, the intersection of the moon's shadow cone with the earth's surface is to be determined. This demanding task is solved with the help of the method developed by Friedrich Wilhelm Bessel .
In rare cases, however, the direction and speed of the shadow path for the moment of the maximum can be specified in a simple way (strictly speaking, this is not a real physical speed, but a projection effect). In the two figures, eclipses with a gamma of approximately zero are selected. The ratio between the speed of the moon's shadow and the speed of rotation of the earth at the equator is assumed to be approximately 2: 1 (black arrows). The vectorial addition gives the direction and the speed of the shadow path of the moon at the place of maximum eclipse relative to the earth's surface (red arrows). The results confirm the directions given by NASA (blue lines) at these locations. In the second example, the location of maximum eclipse is on the Tropic of Capricorn. There the circumferential speed at the earth's surface is lower than at the equator (factor = cos 23.44 ° ≈ 0.92).
The calculation of the course of a future solar eclipse on the earth's surface involves increasing uncertainty as the distance increases. This is because the earth's rotation is not constant. The rotation speed of the earth is permanently reduced by tidal friction , so that the days are on average 17 µs longer per year. These smallest time units add up and are corrected at irregular intervals in the form of leap seconds . The number of leap seconds is included in the calculation of the eclipses as delta T , but can only be estimated for the future using computer models. For eclipses that are more than a few decades in the future, the Delta T can vary by up to several minutes, depending on the model. Since the earth's surface at the equator moves 27.8 km in one minute, the position of the earth's shadow relative to a designated location on the earth's surface shifts accordingly. Of course, this also applies to eclipses in the past, but here the difference between the calculated and reported location of the eclipse is used to reconstruct the delta T in the past.
Belonging to a cycle of darkness
→ Main articles: Eclipse cycles , Saros cycle , Inex cycle
In a canon of eclipses, all eclipses are listed one after the other. On average, nine eclipses follow each other at an interval of six lunations and thus form the semester cycle. The previous and the following semester cycle are either five lunations apart or they overlap the beginning or end of the one under consideration. Semester cycles are seldom nested over two eclipses. Through a special selection of events, eclipse cycles can be specified with an even higher number of eclipses at a greater time interval, with the respective eclipse events in such cycles becoming more similar the longer their period becomes. The Saros cycle is a special cycle ; the eclipses of such a cycle are extremely similar, since the earth and moon are each at almost the same point in their orbit.
Phenomena during a total solar eclipse
A total solar eclipse is one of the most impressive natural phenomena. Several fascinating phenomena can be observed.
Change in brightness
The illuminance decreases to about 1 / 10,000 to 1 / 100,000 of the normal sunshine brightness. That is about 50 to 5 times the brightness of a full moon night. The day almost turns into night. The fastest relative change in brightness takes place shortly (in the last second) before and after the totality phase and also corresponds to the perceived change in brightness.
Light change
Even during the partial phase, the light takes on a lead-colored tint. Shadows become more contoured, and in the shade of trees and bushes a hundredfold sun crescents and light circles form on the ground due to the so-called "pinhole effect" ( camera obscura ). When totality is reached, the horizon is orange-yellow to reddish in color, while the umbra makes the sky appear deep dark blue near the zenith.
Flying shadows
With a narrow sun crescent - about one minute before the 2nd contact and after the 3rd contact - flying shadows can appear. It is a scintillation phenomenon. Due to differences in refraction in the air, the earth is not evenly illuminated, so that with a very narrow crescent of the sun, recognizable stripe patterns form on the ground, which move analogously to the movement in the air. With a broad crescent of the sun or outside of an eclipse, the contrast drops below the limit of perception and detection due to the superimposition of different phases. The term “flying shadows” is factually incorrect, and neither is the English term “ shadow bands” .
Diamond ring or pearl cord effect
In the moments of the 2nd and 3rd contact, the last or the first rays of the sun shine through the valleys of the mountainous moon silhouette and create the impression of a diamond ring or a string of pearls . This effect is called Baily's beads after the British astronomer Francis Baily .
Solar corona and prominences
Between the 2nd and 3rd contact the sun's corona shines around the dark disc of the moon. Depending on the sun's activity , the shape of the corona appears more uniform (maximum) or elongated (minimum). During the total phase, reddish protuberances can also be seen over the edge of the moon .
When observing an annular solar eclipse, the solar corona is not visible. The pearl-string phenomenon can, however, be seen at the 2nd and 3rd contact.
The scientific observation of the sun extends from the photosphere (shortly before the 2nd contact and shortly and after the 3rd contact), over the narrow chromosphere (in the moments of the 2nd and 3rd contact) to the extensive corona and the prominences (between 2nd and 3rd contact).
Visibility of planets and stars
Around the eclipsed sun the brightest planets and fixed stars can be seen.
Temperature drop
Often the temperature drops several degrees during a total solar eclipse. Animals and plants also react to the darkness and the drop in temperature. Birds fall silent and almost all diurnal animals seek their hiding places, while bats and other nocturnal animals leave their hiding places. Flowers close their petals.
Viewing a solar eclipse
When observing a solar eclipse, as in general when observing the sun, great caution is required, as serious eye damage and even blindness can result if you look directly into the sun. Eclipse glasses are required for direct observation , while stronger filters are required when looking through binoculars or telescopes. Only during the short period of a totality phase can the sun protection goggles and the sun filters be removed from optical devices. However, a ring-shaped or partial eclipse must be observed continuously with light filtering.
In contrast, indirect observation of the projected image of the solar disk is also possible with the unprotected eye. In the simplest case, a hole the size of a darning needle in a postcard is sufficient, through which the light figure is thrown outlined in shadow onto a background, similar to a camera obscura .
Emotional experience
A total solar eclipse remains a long memorable event for many who experience it. There are many otherwise completely unfamiliar phenomena that contribute to this: above all the special lighting conditions and their sudden occurrence, the quiet nature, the emerging wind and (if visible) the flying shadow or the visibility of bright stars. Because total eclipses are rare and can only be observed in the narrow central zone , the journey to this event and any preparations are usually remembered.
The Austrian poet Adalbert Stifter described the emotional experience very impressively on the occasion of the solar eclipse on the morning of July 8, 1842 , which he observed in Vienna . From his six-page description, only a few paragraphs are picked out because of Stifter's certain lengthy breathlessness:
“Since I knew that at so and so many hours the moon would move away from under the sun […] and because of the earth's axis rotation it would draw a black stripe over its sphere […] that a black disk seemed to move into the sun, always from it takes away more and more, until only a narrow sickle remains, and finally it disappears too [...] But since it [the total darkness] really arrived, since I was standing on a control tower high above the whole city and saw the apparition with my own eyes Looked at, quite different things happened, of course, of which I had neither waking nor dreaming thought, of which no one thinks who has not seen the miracle.
Never and never in my entire life have I been so shaken as in these two minutes, it was no different as if God had suddenly spoken a clear word and I had understood it. I descended from the lookout, just as Moses might have come down from the burning mountain a thousand and a thousand years ago, with a confused and numb heart [...] At last at the predicted minute - she received the gentle kiss of death, a fine streak of her light gave way to her breath this kiss back, the other edge flowed gently and golden in the glass of the star tube - 'it's coming', those who only looked up with steaming glasses, but otherwise with free eyes […] The first, strange, strange sensation shouted now trickled through the hearts [...]
Do not object that the matter is natural and easy to calculate from the laws of motion of the body; the wonderful magic of beauty that God gave to things does not ask anything about such calculations, it is there because it is there [...] The sublime that overwhelms our soul already resides in the immense space of heaven, and yet this space is in mathematics nothing else but great. [...]
Finally the effects became visible on earth, and more and more, the narrower the glowing sickle in the sky became; the river no longer shimmered, but was a taffeta-gray ribbon, dull shadows lay around, the swallows became restless, the beautiful, gentle shine of the sky [became] leaden light […] - this gradual death in the middle of just a few minutes ago was shocking prevailing freshness of the morning.
We had imagined the dusk to be like going into the evening, only without the sunset ; […] But it was completely different, it was a burdensome and uncanny alienation from our nature; towards the south-east lay a strange, yellow-red darkness […] I took another look into the star tube, it was the last; as narrow as carved into the darkness with the edge of a penknife, only the glowing sickle stood there [...] like the last spark of a dying wick, the last spark of the sun melted away, probably back through the gorge between two moon mountains - it was a very sad moment. Nobody had foreseen that - a unanimous 'Ah' from everyone's lips, and then dead silence, it was the moment when God spoke and people listened. "
Frequency of solar eclipses
There are at least two and a maximum of five solar eclipses every year. The long-term average is 2.38. Between 2000 and 2100, 224 solar eclipses take place, about one third each total, ring-shaped and partial. See the list of 21st century solar eclipses .
- In a certain place
On average, a total solar eclipse can only be expected every 375 years over a certain location. If you add the ring-shaped ones, it's 140 years. The reason for this is that the strip in which a central solar eclipse (total and ring-shaped) takes place is very narrow. In Switzerland the last total solar eclipse on May 22, 1724 took place. In Austria there was no total darkness between July 8, 1842 and in Germany between August 19, 1887 and August 11, 1999 . Germany, Switzerland and Austria will not be hit by a total eclipse until September 3, 2081 .
Deviating from the above-mentioned average frequency of total and ring-shaped solar eclipses, it is quite possible that places have to wait much shorter for a central solar eclipse. For example, in an area east of Ankara ( Turkey ), the total eclipse of August 11, 1999 and that of March 29, 2006 could be seen within just seven years. The inhabitants of a small area of Angola south of the port city of Sumbe had to wait even shorter, namely only 18 months : total eclipses on June 21, 2001 and December 4, 2002 . Switzerland, parts of southern Germany and parts of Austria are also facing such a short interval: total eclipse on September 3, 2081 , ring-shaped eclipse on February 27, 2082 towards evening.
On the other hand, there are places where no total solar eclipse occurs for a period of more than four millennia.
- ↑ The totality path of the solar eclipse of July 8, 1842 touched the south of the Swiss cantons of Ticino and Graubünden. The totality there lasted more than 1 minute. The central line, however, was far outside of Switzerland.
Solar eclipses and space travel
Before space travel , solar physicists relied on the rare solar eclipses to study most of the properties of the sun. In space it is relatively easy to simulate a "solar eclipse" at any time. The sun disk is covered by a suitably large screen at an appropriate distance, for example to photograph and examine the corona. This is not possible on earth because of the scattered light of the earth's atmosphere . However, the inner corona cannot be examined because it is too bright, which is possible during a solar eclipse on Earth. Such simulations are carried out, for example, with the LASCO observation instrument on board the SOHO space probe .
But space travel also plays a role in tracking a solar eclipse on Earth. The first documented observation of an earthly solar eclipse from space comes from Gemini 12 : total solar eclipse on November 12th, 1966. Pictures of the shadow moving over the earth were also made by Mir , the pictures from August 11th, 1999 are among the last pictures before the station is decommissioned. During the total solar eclipse of March 29, 2006 , the International Space Station (ISS) came close to the umbra of the moon, and some images were taken. Conversely, from some places on the earth the ISS could be seen passing in front of the partially eclipsed sun.
Current solar eclipses
The last total solar eclipse took place on July 2, 2019 , it was seen in the Pacific and South America .
The following total solar eclipse will occur on December 14, 2020 in the South Pacific and the South Atlantic .
The next solar eclipse visible in Central Europe will take place on June 10, 2021 , but seen from there only with comparatively little sun coverage.
Dates of all solar eclipses of the 20th and 21st centuries are given in the lists of solar eclipses .
Historically significant solar eclipses
The following solar eclipses have acquired special scientific or other historical significance.
- Solar eclipse of May 28, 585 BC Chr . : This darkness could have been foretold by Thales of Miletus ; thus it would have been the first for which the place and time were predicted. It is also said that this darkness was the cause of the end of the war between the Lydians and the Medes .
- May 3, 1715 : The shadow orbit of this solar eclipse over southern England was predicted by Edmond Halley and the eclipse was probably the first for which such a calculation was attempted.
- July 8, 1842 : This total darkness is best known because of the extensive and very emotional description by Adalbert Stifter . The astronomer Karl Ludwig von Littrow also contributed to the description of the moving event .
- May 29, 1919 : During this eclipse, the gravitational deflection of light predicted by general relativity was checked and confirmed.
- August 11, 1999 : The last total solar eclipse of the second millennium was also the solar eclipse, which was observed by more people than any other solar eclipse in world history.
Solar eclipses on other planets
Eclipses are not the only feature of the earth-moon system, but occur on all planets with moons, both as solar eclipses and as lunar eclipses . But on no other planet in our solar system is the constellation as given as on earth, where the apparent diameters of the sun and moon are almost the same.
On Jupiter , the solar eclipses are caused by its four large moons . Since these are almost in the plane of the orbit of Jupiter around the sun, solar eclipses on Jupiter are almost everyday. The shadow that these moons cast on their planet can already be observed with smaller telescopes .
Solar eclipses are difficult to observe and very rare on the other outer planets , as their equatorial plane, in which the moons orbit, is strongly inclined to the plane of the planet's orbit and the orbital times around the sun are very long. The eclipses caused by the two small moons of Mars can be described as transit , they do not cause any measurable decrease in brightness on Mars.
See also
literature
- Rudolf Kippenhahn , Wolfram Knapp: Black sun, red moon. The eclipse of the century. DVA, Stuttgart 1999, ISBN 3-421-02775-7 (with CD-ROM : The sun - the star from which we live ).
- Andreas Walker: Solar eclipses and other fascinating phenomena in the sky. Birkhäuser, Basel 1999, ISBN 3-7643-6024-0 .
- JP McEvoy: Solar Eclipse. The story of a sensational phenomenon. Berlin-Verlag, Berlin 2001, ISBN 3-8270-0372-5 .
- Hermann Mucke , Jean Meeus : Canon of solar eclipses −2003 to +2526. 2nd Edition. Astronomical Office , Vienna 1999
- Fred Espenak : Thousand Year Canon of Solar Eclipses 1501 to 2500. Astropixels Publishing, Portal 2015, ISBN 978-1-941983-02-7 ( online )
- Fred Espenak: 21st Century Canon of Solar Eclipses. Astropixels Publishing, Portal 2016, ISBN 978-1-941983-12-6 ( online )
- Richard F. Stephenson: Historical eclipses and earth's rotation. Cambridge Univ. Press, Cambridge 1997, ISBN 0-521-46194-4 .
- John M. Steele: Observations and predictions of eclipse times by early astronomers. Kluwer Acad. Publ., Dordrecht 2000, ISBN 0-7923-6298-5 .
Web links
- General
- Wolfgang Strickling: Solar eclipse
- John Walker : On the influence of the relative size of the moon on the type of solar eclipse (English, with animations)
- Spektrum.de : Collection of amateur recordings
- Compilation and calculation
- CalSky: Local solar eclipses - Calculation of the times for date and location
- NASA / Goddard SFC: Solar Eclipses: 2004–2010 (English)
- NASA / Goddard SFC: World map of all total solar eclipses from 2001–2025
- NASA / Goddard SFC: Deviations TDT up to 501 BC Chr.
- NASA / Goddard SFC: Solar eclipses 600–501 BC Chr.
- www.solar-eclipse.de: List of all solar eclipses in Germany (from −2000–3000)
- Robert Harry van Gent: A Catalog of Eclipse Cycles. In: Webpages on the History of Astronomy. September 8, 2003, accessed on August 25, 2011 (English, compilation of all cycles in the series of eclipses).
Remarks
- ↑ The NASA Five Millennium Catalog of Solar Eclipses −1999 to +3000 (2000 BCE to 3000 CE) gives the following distribution: 2 eclipses in 72.5%, 3 eclipses in 17.5%, 4 eclipses in 9.5% and 5 eclipses in 0.5% of the years.
- ↑ An example is the ring-shaped solar eclipse of July 23, 2093 , which will cross the north and east of Germany. While the NASA calculation ( Annular Solar Eclipse of 2093 July 23 Delta T = 187.5 s) sees the Hanseatic City of Hamburg in the zone of annularity, according to the Calsky calculation ( www.calsky.com Delta T = 79.0 s) clearly outside the zone, since the latter calculation sees the central line approx. 25 km to the west.
Individual evidence
- ↑ Dors Unbehaun: Solar eclipses in history at astronomie.de, accessed on May 3, 2015.
- ↑ FR Stephenson, LJ Fatoohi: Thale's Prediction of a Solar Eclipse. In: Journal for the History of Astronomy. No. 11, 1997, p. 279. bibcode : 1997JHA .... 28..279S
- ↑ D. Panchenko: Thales's prediction of a Solar Eclipse. In: Journal for the History of Astronomy. No. 11, 1994, p. 275. bibcode : 1994JHA .... 25..275P
- ↑ Gernot Meiser: From the story. ( Memento from April 24, 2015 in the Internet Archive ) at astronomie.de, accessed on May 3, 2015.
- ↑ Luke 23: 44-45, Matthew 27:45 and Mark 15:33. The Gospel of John does not mention such an event.
- ↑ Berthold Seewald: Reach out your hand to heaven that there will be such darkness in Egypt that it can be grasped. And Moses stretched out his hand to heaven at welt.de, accessed on May 3, 2015.
- ↑ De Eclipsibus, growth in genere, in tum specie De Magna Solis Eclipsi, August d 2. proxime Futura . Jena 1654 ( digitized version )
- ↑ Hans-Ulrich Keller: Compendium of Astronomy . Kosmos, Stuttgart 2008, ISBN 978-3-440-11289-2 , pp. 98-101, see literature
- ^ Date in the proleptic Julian calendar .
- ↑ a b H. Mucke, J. Meeus: Canon of solar eclipses −2003 to +2526. 2nd Edition. Astronomical Office , Vienna 1999 Astronomical Office, Vienna: Publications or Canon of the Eclipses by Theodor Oppolzer , 1887.
- ↑ Hans-Ulrich Keller: Compendium of Astronomy . Kosmos, Stuttgart 2008, ISBN 978-3-440-11289-2 , pp. 103-109, see literature
- ↑ From Five Millennium Canon of Solar Eclipses: −1999 to +3000
- ^ J. Meeus: Mathematical Astronomy Morsels IV . Willmann-Bell, Richmond 2007, ISBN 978-0-943396-87-3 , chap. 8th
- ↑ All other eclipse cycles are cycles won by selection. The more eclipses are skipped, the easier it is to form longer and longer rows in which the change in the node distance from darkness to darkness is always smaller.
- ↑ From Five Millennium Canon of Solar Eclipses: −1999 to +3000
- ↑ about 3400 km / h to 1700 km / h; 6. The course of a total solar eclipse
- ^ For example: Theodor Oppolzer , Canon der Finsternisse , memoranda of the Imperial Academy of Sciences, mathematical and natural science class, L II vol, Vienna 1887.
- ↑ Solar eclipse: Do not look directly into the sun. on: test.de , March 16, 2015, accessed on March 17, 2015.
- ↑ Adalbert Stifter: The solar eclipse on July 8, 1842. from: www.strickling.net , accessed on March 19, 2015.
- ^ J. Meeus: Mathematical Astronomy Morsels. Willmann-Bell, 1997, ISBN 0-943396-51-4 , p. 88 ff.
- ^ J. Meeus: More Mathematical Astronomy Morsels. Willmann-Bell, 2002, ISBN 0-943396-74-3 , pp. 98ff.
- ↑ Jay M. Pasachoff: Eclipse researchers hope for a clear view. In: Spiegel-online . March 29, 2006.
- ↑ Looking Back on an Eclipsed Earth - Astronomy Picture of the Day of August 30, 1999 (English).
- ↑ astronomie.info: Two simultaneous eclipses - the moon and the space station ISS in front of the sun
- ↑ JP McEvoy: Solar Eclipse. The story of a sensational phenomenon. 2001, p. 120.
- ^ Adalbert Stifter : The solar eclipse on July 8, 1842 .
- ↑ JP McEvoy: Solar Eclipse. The story of a sensational phenomenon. 2001, p. 197.
- ↑ a b c R. Kippenhahn, W. Knapp: Black sun, red moon. 1999, pp. 196-204.
| Passages in our solar system | ||||||
|---|---|---|---|---|---|---|
| Venus | earth | Mars | Jupiter | Saturn | Uranus | Neptune |
| Mercury | Mercury | Mercury | Mercury | Mercury | Mercury | Mercury |
| Venus | Venus | Venus | Venus | Venus | Venus | |
| earth | earth | earth | earth | earth | ||
| Mars | Mars | Mars | Mars | |||
| Jupiter | Jupiter | Jupiter | ||||
| moon | Deimos | Saturn | Saturn | |||
| Phobos | Uranus | |||||