Alfred Wegener

Alfred Wegener
Alfred Wegener ca.1924-30.jpg
Wegener, circa 1924–1930
Alfred Lothar Wegener

(1880-11-01)1 November 1880
DiedNovember 1930 (aged 50)
Alma materUniversity of Berlin (Ph.D.)
Known forContinental drift theory
Scientific career
FieldsClimatology, geology, geophysics, meteorology
Doctoral advisorJulius Bauschinger
InfluencedJohannes Letzmann
Alfred Wegener Signature.svg

Alfred Lothar Wegener (/ˈvɡənər/;[1] German: [ˈʔalfʁeːt ˈveːɡənɐ];[2][3] 1 November 1880 – November 1930) was a German climatologist, geologist, geophysicist, meteorologist, and polar researcher.

During his lifetime he was primarily known for his achievements in meteorology and as a pioneer of polar research, but today he is most remembered as the originator of continental drift hypothesis by suggesting in 1912 that the continents are slowly drifting around the Earth (German: Kontinentalverschiebung). His hypothesis was controversial and widely rejected by mainstream geology until the 1950s, when numerous discoveries such as palaeomagnetism provided strong support for continental drift, and thereby a substantial basis for today's model of plate tectonics.[4][5] Wegener was involved in several expeditions to Greenland to study polar air circulation before the existence of the jet stream was accepted. Expedition participants made many meteorological observations and were the first to overwinter on the inland Greenland ice sheet and the first to bore ice cores on a moving Arctic glacier.


Early life and education

Alfred Wegener was born in Berlin on 1 November 1880 as the youngest of five children in a clergyman's family. His father, Richard Wegener, was a theologian and teacher of classical languages at the Berlinisches Gymnasium zum Grauen Kloster. In 1886 his family purchased a former manor house near Rheinsberg, which they used as a vacation home. Today there is an Alfred Wegener Memorial site and tourist information office in a nearby building that was once the local schoolhouse.[6] He was cousin to film pioneer Paul Wegener.

Commemorative plaque on Wegener's former school in Wallstrasse

Wegener attended school at the Köllnisches Gymnasium on Wallstrasse in Berlin (a fact which is memorialized on a plaque on this protected building, now a school of music), graduating as the best in his class. Afterward he studied Physics, meteorology and Astronomy in Berlin, Heidelberg and Innsbruck. From 1902 to 1903 during his studies he was an assistant at the Urania astronomical observatory. He obtained a doctorate in astronomy in 1905 based on a dissertation written under the supervision of Julius Bauschinger at Friedrich Wilhelms University (today Humboldt University), Berlin. Wegener had always maintained a strong interest in the developing fields of meteorology and climatology and his studies afterwards focused on these disciplines.

In 1905 Wegener became an assistant at the Aeronautisches Observatorium Lindenberg near Beeskow. He worked there with his brother Kurt, two years his senior, who was likewise a scientist with an interest in meteorology and polar research. The two pioneered the use of weather balloons to track air masses. On a balloon ascent undertaken to carry out meteorological investigations and to test a celestial navigation method using a particular type of quadrant (“Libellenquadrant”), the Wegener brothers set a new record for a continuous balloon flight, remaining aloft 52.5 hours from 5–7 April 1906.[7]

First Greenland expedition and years in Marburg

In that same year 1906, Wegener participated in the first of his four Greenland expeditions, later regarding this experience as marking a decisive turning point in his life. The Denmark expedition was led by the Dane Ludvig Mylius-Erichsen and charged with studying the last unknown portion of the northeastern coast of Greenland. During the expedition Wegener constructed the first meteorological station in Greenland near Danmarkshavn, where he launched kites and tethered balloons to make meteorological measurements in an Arctic climatic zone. Here Wegener also made his first acquaintance with death in a wilderness of ice when the expedition leader and two of his colleagues died on an exploratory trip undertaken with sled dogs.

After his return in 1908 and until World War I, Wegener was a lecturer in meteorology, applied astronomy and cosmic physics at the University of Marburg. His students and colleagues in Marburg particularly valued his ability to clearly and understandably explain even complex topics and current research findings without sacrificing precision. His lectures formed the basis of what was to become a standard textbook in meteorology, first written In 1909/1910: Thermodynamik der Atmosphäre (Thermodynamics of the Atmosphere), in which he incorporated many of the results of the Greenland expedition.

On 6 January 1912 he publicized his first thoughts about continental drift in a lecture at a session of the Geologischen Vereinigung at the Senckenberg Museum, Frankfurt am Main and in three articles in the journal Petermanns Geographische Mitteilungen.[8]

Second Greenland expedition

After a stopover in Iceland to purchase and test ponies as pack animals, the expedition arrived in Danmarkshavn. Even before the trip to the inland ice began the expedition was almost annihilated by a calving glacier. The Danish expedition leader, Johan Peter Koch, broke his leg when he fell into a glacier crevasse and spent months recovering in a sickbed. Wegener and Koch were the first to winter on the inland ice in northeast Greenland.[9] Inside their hut they drilled to a depth of 25 m with an auger. In summer 1913 the team crossed the inland ice, the four expedition participants covering a distance twice as long as Fridtjof Nansen's southern Greenland crossing in 1888. Only a few kilometers from the western Greenland settlement of Kangersuatsiaq the small team ran out of food while struggling to find their way through difficult glacial breakup terrain. But at the last moment, after the last pony and dog had been eaten, they were picked up at a fjord by the clergyman of Upernavik, who just happened to be visiting a remote congregation at the time.


Later in 1913, after his return Wegener married Else Köppen, the daughter of his former teacher and mentor, the meteorologist Wladimir Köppen. The young pair lived in Marburg, where Wegner resumed his university lectureship. There his two older daughters were born, Hilde (1914–1936) and Sophie ("Käte", 1918–2012). Their third daughter Hanna Charlotte ("Lotte", 1920–1989) was born in Hamburg. Lotte would in 1938 marry the famous Austrian mountaineer and adventurer Heinrich Harrer, while in 1939, Käte married Siegfried Uiberreither, Austrian Nazi Gauleiter of Styria.[10]

World War I

As an infantry reserve officer Wegener was immediately called up when the First World War began in 1914. On the war front in Belgium he experienced fierce fighting but his term lasted only a few months: after being wounded twice he was declared unfit for active service and assigned to the army weather service. This activity required him to travel constantly between various weather stations in Germany, on the Balkans, on the Western Front and in the Baltic region.

Nevertheless, he was able in 1915 to complete the first version of his major work, Die Entstehung der Kontinente und Ozeane (“The Origin of Continents and Oceans”). His brother Kurt remarked that Alfred Wegener's motivation was to “reestablish the connection between geophysics on the one hand and geography and geology on the other, which had become completely ruptured because of the specialized development of these branches of science.”

Interest in this small publication was however low, also because of wartime chaos. By the end of the war Wegener had published almost 20 additional meteorological and geophysical papers in which he repeatedly embarked for new scientific frontiers. In 1917 he undertook a scientific investigation of the Treysa meteorite.

Postwar period and third expedition

Wegener obtained a position as a meteorologist at the German Naval Observatory (Deutsche Seewarte) and moved to Hamburg with his wife and their two daughters. In 1921 he was appointed senior lecturer at the new University of Hamburg. From 1919 to 1923 Wegener did pioneering work on reconstructing the climate of past eras (now known as "paleoclimatology"), closely in collaboration with Milutin Milanković,[11] publishing Die Klimate der geologischen Vorzeit (“The Climates of the Geological Past”) together with his father-in-law, Wladimir Köppen, in 1924.[12] In 1922 the third, fully revised edition of “The Origin of Continents and Oceans” appeared, and discussion began on his theory of continental drift, first in the German language area and later internationally. Withering criticism was the response of most experts.

In 1924 Wegener was appointed to a professorship in meteorology and geophysics in Graz, which finally provided him with a secure position for himself and his family. He concentrated on physics and the optics of the atmosphere as well as the study of tornadoes. He had studied tornadoes for several years by this point, publishing the first thorough European tornado climatology in 1917. He also posited tornado vortex structures and formative processes.[13] Scientific assessment of his second Greenland expedition (ice measurements, atmospheric optics, etc.) continued to the end of the 1920s.

In November 1926 Wegener presented his continental drift theory at a symposium of the American Association of Petroleum Geologists in New York City, again earning rejection from everyone but the chairman. Three years later the fourth and final expanded edition of “The Origin of Continents and Oceans” appeared.

In 1929 Wegener embarked on his third trip to Greenland, which laid the groundwork for a later main expedition and included a test of an innovative, propeller-driven snowmobile.

Fourth and last expedition

Wegener (left) and Villumsen (right) in Greenland; 1 November 1930.

Wegener's last Greenland expedition was in 1930. The 14 participants under his leadership were to establish three permanent stations from which the thickness of the Greenland ice sheet could be measured and year-round Arctic weather observations made. Wegener felt personally responsible for the expedition's success, as the German government had contributed $120,000 ($1.5 million in 2007 dollars). Success depended on enough provisions being transferred from West camp to Eismitte ("mid-ice") for two men to winter there, and this was a factor in the decision that led to his death. Owing to a late thaw, the expedition was six weeks behind schedule and, as summer ended, the men at Eismitte sent a message that they had insufficient fuel and so would return on 20 October.

Vehicles used by the 1930 expedition (stored).

On 24 September, although the route markers were by now largely buried under snow, Wegener set out with thirteen Greenlanders and his meteorologist Fritz Loewe to supply the camp by dog sled. During the journey, the temperature reached −60 °C (−76 °F) and Loewe's toes became so frostbitten they had to be amputated with a penknife without anesthetic. Twelve of the Greenlanders returned to West camp. On 19 October the remaining three members of the expedition reached Eismitte. There being only enough supplies for three at Eismitte, Wegener and Rasmus Villumsen took two dog sleds and made for West camp. They took no food for the dogs and killed them one by one to feed the rest until they could run only one sled. While Villumsen rode the sled, Wegener had to use skis, but they never reached the camp: Wegener died and Villumsen was never seen again. The expedition was completed by his brother, Kurt Wegener.

This expedition inspired the Greenland expedition episode of Adam Melfort in John Buchan's 1933 novel A Prince of the Captivity.


Wegener died in Greenland in November 1930 while returning from an expedition to bring food to a group of researchers camped in the middle of an icecap.[14] He supplied the camp successfully, but there was not enough food at the camp for him to stay there. He and a colleague, Rasmus Villumsen, took dog sleds to travel to another camp although they never reached it. Villumsen had buried the body with great care, and a pair of skis marked the grave site. After burying Wegener, Villumsen had resumed his journey to West camp, but was never seen again. Six months later, on 12 May 1931, Kurt Wegener discovered his brother's grave halfway between Eismitte and West camp. He and other expedition members built a pyramid-shaped mausoleum in the ice and snow, and Alfred Wegener's body was laid to rest in it.[15] Wegener had been 50 years of age and a heavy smoker, and it was believed that he had died of heart failure brought on by overexertion. Villumsen was 23 when he died, and it is estimated that his body, and Wegener's diary, now lie under more than 100 metres (330 ft) of accumulated ice and snow.

Continental drift theory

Original world maps created by Alfred Wegener showing Pangaea and the continents drifting apart. Its spatial and temporal classification corresponds to his conception at that time, not to the later proven positions and geological epochs.

Alfred Wegener first thought of this idea by noticing that the different large landmasses of the Earth almost fit together like a jigsaw puzzle. The continental shelf of the Americas fits closely to Africa and Europe. Antarctica, Australia, India and Madagascar fit next to the tip of Southern Africa. But Wegener only published his idea after reading a paper in 1911 which criticized the prevalent hypothesis, that a bridge of land once connected Europe and America, on the grounds that this contradicts isostasy.[16] Wegener's main interest was meteorology, and he wanted to join the Denmark-Greenland expedition scheduled for mid-1912. He presented his Continental Drift hypothesis on 6 January 1912. He analyzed both sides of the Atlantic Ocean for rock type, geological structures and fossils. He noticed that there was a significant similarity between matching sides of the continents, especially in fossil plants.

Fossil patterns across continents (Gondwana).

From 1912, Wegener publicly advocated the existence of "continental drift", arguing that all the continents were once joined together in a single landmass and had since drifted apart. He supposed that the mechanisms causing the drift might be the centrifugal force of the Earth's rotation ("Polflucht") or the astronomical precession. Wegener also speculated about sea-floor spreading and the role of the mid-ocean ridges, stating that "the Mid-Atlantic Ridge ... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth."[17] However, he did not pursue these ideas in his later works.

In 1915, in the first edition of his book, Die Entstehung der Kontinente und Ozeane, written in German,[18] Wegener drew together evidence from various fields to advance the theory that there had once been a giant continent, which he named "Urkontinent"[19] (German for "primal continent", analogous to the Greek "Pangaea",[20] meaning "All-Lands" or "All-Earth"). Expanded editions during the 1920s presented further evidence. (The first English edition was published in 1924 as The Origin of Continents and Oceans, a translation of the 1922 third German edition.) The last German edition, published in 1929, revealed the significant observation that shallower oceans were geologically younger. It was, however, not translated into English until 1962.[18]

Wegener during J.P. Koch's Expedition 1912–1913 in the winter base "Borg".


In his work, Wegener presented a large amount of observational evidence in support of continental drift, but the mechanism remained a problem, partly because Wegener's estimate of the velocity of continental motion, 250 cm/year, was too high.[21] (The currently accepted rate for the separation of the Americas from Europe and Africa is about 2.5 cm/year.)[22]

While his ideas attracted a few early supporters such as Alexander Du Toit from South Africa, Arthur Holmes in England [23] and Milutin Milanković in Serbia, for whom continental drift theory was the premise for investigating polar wandering,[24][25] the hypothesis was initially met with skepticism from geologists, who viewed Wegener as an outsider and were resistant to change.[23] The one American edition of Wegener's work, published in 1925, which was written in "a dogmatic style that often results from German translations",[23] was received so poorly that the American Association of Petroleum Geologists organized a symposium specifically in opposition to the continental drift hypothesis.[26] The opponents argued, as did the Leipziger geologist Franz Kossmat, that the oceanic crust was too firm for the continents to "simply plough through".

From at least 1910, Wegener imagined the continents once fitting together not at the current shore line, but 200 m below this, at the level of the continental shelves, where they match well.[23] Part of the reason Wegener's ideas were not initially accepted was the misapprehension that he was suggesting the continents had fit along the current coastline.[23] Charles Schuchert commented:

During this vast time [of the split of Pangea] the sea waves have been continuously pounding against Africa and Brazil and in many places rivers have been bringing into the ocean great amounts of eroded material, yet everywhere the geographic shore lines are said to have remained practically unchanged! It apparently makes no difference to Wegener how hard or how soft are the rocks of these shore lines, what are their geological structures that might aid or retard land or marine erosion, how often the strand lines have been elevated or depressed, and how far peneplanation has gone on during each period of continental stability. Furthermore, sea-level in itself has not been constant, especially during the Pleistocene, when the lands were covered by millions of square miles of ice made from water subtracted out of the oceans. In the equatorial regions, this level fluctuated three times during the Pleistocene, and during each period of ice accumulation the sea-level sank about 250 feet [75 m].

Wegener was in the audience for this lecture, but made no attempt to defend his work, possibly because of an inadequate command of the English language.

In 1943, George Gaylord Simpson wrote a strong critique of the theory (as well as the rival theory of sunken land bridges) and gave evidence for the idea that similarities of flora and fauna between the continents could best be explained by these being fixed land masses which over time were connected and disconnected by periodic flooding, a theory known as permanentism.[27] Alexander du Toit wrote a rejoinder to this the following year.[28]

Modern developments

The tectonic plates of the world were mapped in the second half of the 20th century.

In the early 1950s, the new science of paleomagnetism pioneered at the University of Cambridge by S. K. Runcorn and at Imperial College by P.M.S. Blackett was soon producing data in favour of Wegener's theory. By early 1953 samples taken from India showed that the country had previously been in the Southern hemisphere as predicted by Wegener. By 1959, the theory had enough supporting data that minds were starting to change, particularly in the United Kingdom where, in 1964, the Royal Society held a symposium on the subject.[29]

The 1960s saw several relevant developments in geology, notably the discoveries of seafloor spreading and Wadati–Benioff zones, and this led to the rapid resurrection of the continental drift hypothesis in the form of its direct descendant, the theory of plate tectonics. Maps of the geomorphology of the ocean floors created by Marie Tharp in cooperation with Bruce Heezen were an important contribution to the paradigm shift that was starting. Wegener was then recognized as the founding father of one of the major scientific revolutions of the 20th century.

With the advent of the Global Positioning System (GPS), it became possible to measure continental drift directly.[30]

Awards and honors

The Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, was established in 1980 on Wegener's centenary. It awards the Wegener Medal in his name.[31] The crater Wegener on the Moon and the crater Wegener on Mars, as well as the asteroid 29227 Wegener and the peninsula where he died in Greenland (Wegener Peninsula near Ummannaq,71°12′N 51°50′W / 71.200°N 51.833°W / 71.200; -51.833), are named after him.[32]

The European Geosciences Union sponsors an Alfred Wegener Medal & Honorary Membership "for scientists who have achieved exceptional international standing in atmospheric, hydrological or ocean sciences, defined in their widest senses, for their merit and their scientific achievements."[33]

Selected works

  • Wegener, Alfred (1911). Thermodynamik der Atmosphäre [Thermodynamics of the Atmosphere] (in German). Leipzig: Verlag Von Johann Ambrosius Barth. (in German)
  • Wegener, Alfred (1912). "Die Herausbildung der Grossformen der Erdrinde (Kontinente und Ozeane), auf geophysikalischer Grundlage". Petermanns Geographische Mitteilungen (in German). 63: 185–195, 253–256, 305–309. Presented at the annual meeting of the German Geological Society, Frankfurt am Main (6 January 1912).CS1 maint: postscript (link)
  • Wegener, Alfred (July 1912). "Die Entstehung der Kontinente". Geologische Rundschau (in German). 3 (4): 276–292. Bibcode:1912GeoRu...3..276W. doi:10.1007/BF02202896. S2CID 129316588.
  • Wegener, Alfred (1922). Die Entstehung der Kontinente und Ozeane [The Origin of Continents and Oceans] (in German). ISBN 3-443-01056-3. LCCN unk83068007.
  • Wegener, Alfred (1929). Die Entstehung der Kontinente und Ozeane [The Origin of Continents and Oceans] (in German) (4 ed.). Braunschweig: Friedrich Vieweg & Sohn Akt. Ges. ISBN 3-443-01056-3.
    • English language edition:Wegener, Alfred (1966). The Origin of Continents and Oceans. New York: Dover. ISBN 0-486-61708-4. Translated from the fourth revised German edition by John Biram.CS1 maint: postscript (link); British edition: Methuen, London (1968).
  • Köppen, W. & Wegener, A. (1924): Die Klimate der geologischen Vorzeit, Borntraeger Science Publishers. English language edition: The Climates of the Geological Past 2015.
  • Wegener, Elsie; Loewe, Fritz, eds. (1939). Greenland Journey, The Story of Wegener's German Expedition to Greenland in 1930–31 as told by Members of the Expedition and the Leader's Diary. London: Blackie & Son Ltd. Translated from the seventh German edition by Winifred M. Deans.CS1 maint: postscript (link)

See also

  • Hair ice – Wegener introduced a theory on the growth of hair ice in 1918.


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  12. ^ Köppen, W. & Wegener, A. (1924): Die Klimate der geologischen Vorzeit, Borntraeger Science Publishers. In English as The Climates of the Geological Past (2015).
  13. ^ Antonescu, Bogdan; H. M. A. M. Ricketts; D. M. Schultz (2019). "100 Years Later: Reflecting on Alfred Wegener's Contributions to Tornado Research in Europe". Bull. Amer. Meteor. Soc. 100 (4): 567–578. Bibcode:2019BAMS..100..567A. doi:10.1175/BAMS-D-17-0316.1. Archived from the original on 27 July 2019. Retrieved 27 July 2019.
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  17. ^ Jacoby, W. R. (January 1981). "Modern concepts of earth dynamics anticipated by Alfred Wegener in 1912". Geology. 9 (1): 25–27. Bibcode:1981Geo.....9...25J. doi:10.1130/0091-7613(1981)9<25:MCOEDA>2.0.CO;2.
  18. ^ a b Frankel, Henry R. (2012). The Continental Drift Controversy: Volume 1, Wegener and the Early Debate. Cambridge: Cambridge University Press. pp. 152, 584. ISBN 978-0-521-87504-2.
  19. ^ According to the OED, 2d edition (1989), the word is not found in the 1915 edition of Wegener's text; it appears in the 1920 edition but with no indication that Wegener coined it.
  20. ^ W.A.J.M. van Waterschoot van der Gracht; Bailey Willis; Rollin T. Chamberlin; et al. (1928). W.A.J.M. van Waterschoot van der Gracht (ed.). Theory of Continental Drift: a symposium on the origin and movement of land masses both intercontinental and intracontinental as proposed by Alfred Wegener, A Symposium of the American Association of Petroleum Geologists (AAPG, 1926). Tulsa, Okla. p. 240.
  21. ^ University of California Museum of Paleontology, Alfred Wegener (1880–1930) Archived 8 December 2017 at the Wayback Machine (accessed 30 April 2015).
  22. ^ Unavco Plate Motion Calculator Archived 25 April 2015 at the Wayback Machine (accessed 30 April 2015).
  23. ^ a b c d e Drake, Ellen T. (1 January 1976). "Alfred Wegener's reconstruction of Pangea". Geology. 4 (1): 41. Bibcode:1976Geo.....4...41D. doi:10.1130/0091-7613(1976)4<41:AWROP>2.0.CO;2.
  24. ^ Mathematische Klimalehre und astronomische Theorie der Klimaschwankungen. in W. Köppen & R. Geiger (Hrsg.): Handbuch der Klimatologie Bd. 1: Allgemeine Klimalehre. Borntraeger, Berlin, 1930
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  27. ^ Simpson, G.G. (1943). "Mammals and the Nature of Continents". American Journal of Science. 241 (1): 1–31. Bibcode:1943AmJS..241....1S. doi:10.2475/ajs.241.1.1. Archived from the original on 29 July 2017. Retrieved 29 July 2017.
  28. ^ du Toit, A. (1944). "Tertiary Mammals and Continental Drift". American Journal of Science. 242 (3): 145–63. Bibcode:1944AmJS..242..145D. doi:10.2475/ajs.242.3.145.
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External links

Media files used on this page

Plates tect2 en.svg
The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which float on the fluid-like (visco-elastic solid) asthenosphere. The relative fluidity of the asthenosphere allows the tectonic plates to undergo motion in different directions. This map shows 15 of the largest plates. Note that the Indo-Australian Plate may be breaking apart into the Indian and Australian plates, which are shown separately on this map.
Cumulus clouds in fair weather.jpeg
Author/Creator: Michael Jastremski, Licence: CC BY-SA 2.0
Cumulus clouds in fair weather. Photograph taken by Michael Jastremski.
The Earth seen from Apollo 17 with transparent background.png
"The Blue Marble" is a famous photograph of the Earth taken on December 7, 1972 by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometers (18,000 statute miles). It shows Africa, Antarctica, and the Arabian Peninsula.
Crab Nebula.jpg
This is a mosaic image, one of the largest ever taken by NASA's Hubble Space Telescope, of the Crab Nebula, a six-light-year-wide expanding remnant of a star's supernova explosion. Japanese and Chinese astronomers recorded this violent event in 1054 CE, as did, almost certainly, Native Americans.

The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the center of the nebula is the dynamo powering the nebula's eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star.

The Crab Nebula derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844, using a 36-inch telescope. When viewed by Hubble, as well as by large ground-based telescopes such as the European Southern Observatory's Very Large Telescope, the Crab Nebula takes on a more detailed appearance that yields clues into the spectacular demise of a star, 6,500 light-years away.

The newly composed image was assembled from 24 individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000. The colors in the image indicate the different elements that were expelled during the explosion. Blue in the filaments in the outer part of the nebula represents neutral oxygen, green is singly-ionized sulfur, and red indicates doubly-ionized oxygen.
Author/Creator: ESO, European Southern Observatory, Licence: CC BY 4.0
Artist's impression of "the oldest star of our Galaxy": HE 1523-0901
  • About 13.2 billion years old
  • Approximately 7500 light years far from Earth
  • Published as part of Hamburg/ESO Survey in the May 10 2007 issue of The Astrophysical Journal
This view of the rising Earth greeted the Apollo 8 astronauts as they came from behind the Moon after the fourth nearside orbit. Earth is about five degrees above the horizon in the photo. The unnamed surface features in the foreground are near the eastern limb of the Moon as viewed from Earth. The lunar horizon is approximately 780 kilometers from the spacecraft. Width of the photographed area at the horizon is about 175 kilometers. On the Earth 240,000 miles away, the sunset terminator bisects Africa.
Solar system.jpg
This is a montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune. The spacecraft responsible for these images are as follows:
  • the Mercury image was taken by Mariner 10,
  • the Venus image by Magellan,
  • the Earth and Moon images by Galileo,
  • the Mars image by Mars Global Surveyor,
  • the Jupiter image by Cassini, and
  • the Saturn, Uranus and Neptune images by Voyager.
  • Pluto is not shown as it is no longer a planet. The inner planets (Mercury, Venus, Earth, Moon, and Mars) are roughly to scale to each other; the outer planets (Jupiter, Saturn, Uranus, and Neptune) are roughly to scale to each other. PIA 00545 is the same montage with Neptune shown larger in the foreground. Actual diameters are given below:
  • Sun (to photosphere) 1,392,684 km
  • Mercury 4,879.4 km
  • Venus 12,103.7 km
  • Earth 12,756.28 km
  • Moon 3,476.2 km
  • Mars 6,804.9 km
  • Jupiter 142,984 km
  • Saturn 120,536 km
  • Uranus 51,118 km
  • Neptune 49,528 km
Wegener Expedition-1930 008.jpg
Photograph of the German expedition and overwintering in Greenland
Wegener Expedition-1930 18.jpg

Photographs of the German expedition and overwintering in Greenland in 1930/31; Deutsche Grönlandexpedition Alfred Wegener; Motorschlitten "Eisbär" und "Schneespatz"; dieser Typ Propellerschlitten wurde ursprünglich in Finnland hergestellt von "Finnish State Aircraft Manufaetory" - zur Überquerung des Bottnischen Meerbusens; Maße: ca. 2 x 6 m; Kabine für 2 Piloten; Stahlrahmen mit Sperrholz; Motor: Siemens-Sh-12; 112 PS; Schlittengewicht ohne Motor: 250 kg;

Wegener Expedition-1930 026.jpg
Photograph of the German expedition and overwintering in Greenland - Alfred Wegener (left) and Rasmus Villumsen (inuit) at station Eismitte. Last photo, both died presumably around the 16th November on the way back to the coast.
Alfred-Wegener-Gedenktafel, Wallstraße 42, Berlin-Mitte, 533-639.jpg
Author/Creator: Lotse, Licence: CC BY-SA 3.0
Gedenktafel für Alfred Wegener am ehemaligen Köllnischen Gymnasium, an der Ecke Wallstraße 42 in Berlin-Mitte.
Alfred Wegener Signature.svg
Alfred Wegener's signature.