Climatic and Astronomical Events from the 4th to 11th Century

This table tries to compare events in Arthurian literature with external historical and astronomical events.

It includes a list of calculated dates of appearances of Halley’s Comet (53) and Solar/Lunar eclipses in Britain as calculated by NASA against such events recorded in medieval manuscripts.

Key to sources
BD: Bede,
NH: Nennius,
AC: Annales Cambrae,
ASC: Anglo-Saxon Chronical,
GLD: Gildas,
RW: Roger of Wendover





Historical Events


37416 Feb 374   Halley’s Comet. This event remained above magnitude 0 for 10 weeks 
375375-392 Valentinian II 
378378 – 448 St Germanus of Auxerre 
381 ASC: This year Maximus the Caesar came to the empire. He was born in the land of Britain
383Magnus Maximus appointed governor of Britain: takes large proportion of British to Gaul & defeats GratianNH: Maximian took 30,000 soldiers to Gaul
388Maximus killed at Aquileia 
391‘Bright globes’ at night merged into a ‘sword’. ‘Time of Theodosius’. Possibly comet of 390. 
399Stilicho save Britain 
407Barbarians cross frozen Rhine


407-411 Constantine III emperor in Britain. Constantine II in Geofrey’s Historia appointed by Gracianus (Gratian?) soldiers of Maximus

409Britain devastated by Saxons 
410Plague & Famine in Rome – Honorius 
411Constantius III defeated Gerontius, the general of usurper Maximus, and Constantine III, 
421Constantius III co-emperor of the Western Empire with Honorius for 7 monthsBD: 420 Then the Romans ceased to rule in Britain, almost 470 years after Caius Julius Caesar entered the island
424424-450 Valentinian IIIBD: 426-447 a severe plague fell upon that corrupt generation
433433-454 Flavius AetiusASC: Appeal by Britons for help against Picts and Irish
GLD: To Aetius, now consul for the third time: the groans of the Britains
BD: King Vortigern to call over to their aid, from the parts beyond the sea, the Saxon nation
446 BD: 446. To Ætius, thrice Consul, the groans of the Britons.
447 RW: Scots and Picts rise up against Vortigern
448378 – 448 St Germanus of AuxerreGLD: a pestilential disease mortally affected


RW: Germanus defeats Scots and Picts

RW:  Scots and Picts rise up against Vortigern
449449 Marcian III made emperor with ValentinianGLD:? Proud tyrant invites 3 keels of saxons
BD: Martian & Valentinian ruled the empire seven years. Then Saxons, invited by the aforesaid king, arrived in three long ships.
RW: Vortigern invites Hengest & Horsa to Britain – 3 keels
ASC: Vortigern invites Hengest & Horsa to Britain
451Halley’s Comet


451AD Annals of Sung Halley’s Comet

451 A.D. Comet. Hydatius Bishop of Aquae Flaviae. This appearance coincided with Attila the Huns fall

451 Aetius and Theodoric I defeats Attila

GLD:? The country ravaged by fire and all the towns destroyed
BD: Arrival of Saxons. Hengest & Horsa invited by Vortigren
NH: Constantine, brother of Aldroen. Sons Constans, Uther, Aurelius Ambrosius
455455 19/1 total lunar eclipseASC: Hengest & Horsa fights Vortigern at Aylesford
NH:? Vortgern kills Constans and becomes king


NH:? Hengest & Horsa invited by Vortigren

 455 Aetius & Valentinium III killed by Petronius Maximus 
457Leo I 457-474ASC: Hengest kills 4000 Britons
458total solar eclipseNH:? St Gerrmanus admonishes Vortigern
460460-465 Emperor Libius SeverusRW: Vortigern invites Hengest to Britain
464464 partial solar eclipseRW: Britons send message for help to Aurelius Ambrosius and his brother Uther in Brittany
466 ASC: Hengest defeats Welsh near Wipped’s Creek


RW: Ambrosius attacks Vortigern who has killed his father and brother

467467-472 Emperor Anthemius recruited the Breton Riothamus living in Armorica to fight Euricus 
473 RW: Ambrosius defeats Saxons at Wipedesfleet
474474-491 Zeno last western emperorBD: Chronica Majora; In the reign of Zeno, the Britons, under the leadership of Ambrosius Aurelianus defeated them
480 BD: 447 or 480 The Saxons were received by Vortigern, four hundred and forty-seven years after the passion of Christ, and, according to the tradition of our ancestors
487 RW: Ambrosius Aurelius slew a great multitude of Saxons
490 RW: Ambrosius Aurelius besieges York with Merlin
494 GLD: 494? Ambrosius Aurelius battle Baddon hill- 44 years after the landing of the saxons and Gildas’ birth
BD: Ambrosius Aurelius. Under him till the year of the siege of Baddesdownhill, about fortyfour years after their arrival in England
495 ASC: Cerdic and Cynric his son came to Britain, fought with the Welsh the same day.  Then Cerdic died and Cynric reigned for 26 years
497 GLD: external wars stop but civil war continues
RW: death of Aurelius Ambrosius and star on a fiery ball like a dragon
498 GLD: 498? 5 Tyrants; Constantius of Dumnonia, Aurelius Caninus, Vortiporius, Cuneglasus, Maglocunus (Maelgwn)
RW: Coronation of Uther Pendragon
500 NH:  The Saxons were received by Vortigern, four hundred and forty-seven years after the passion of Christ,
501 ASC:  Beda & Bela slew a young Britain of high rank
507partial solar eclipse 
508 ASC:  Cerdic and Cynric slew a British king whose name was Natanleod
514 ASC: at Cerdic’s-ore. Stuff and Wihtgar fought with the Britons, and put them to flight
516 ANC: Battle of Baddon
RW: Death of Uther and Arthur crowned King; a youth of 15 years
519 ASC: Cerdic & Cynric establishes Wessex kingdom after battle of Cerdicesford
520 NH: when Arthur penetrated to the hill of Badon.


RW: Arthur at Baddon

525Anno Domini starts for dating 
527527 -565 JustinianRW: Justinian begins reign
530530 AD Chinese Annals of Wei (83) Halley’s CometASC: 530 This year Cerdic and Cynric took the Isle of Wight, and slew many men.
534 ASC Cerdic died and son Cynric reigned for 26 yrs
536536-546 Tree ring growth.


Volcanic winter 536-7 Procopius “a grave portent”. whole year “the Sun sent forth his rays without his usual brilliance. Cassiodorus “The Sun lost its wonted light and seems of a bluish colour. We marvel to see no shadows of our bodies at noon”

536 partial solar eclipse 
537537 Siege of Rome (537–38) Gothic War.AC: Camlann and the death of Arthur and Medraut.  and there was plague in Britain and Ireland
RW: Arthur Slays Lucas Roman Consul
538538 31/1 total lunar eclipseASC: 538 Eclipse of the sun lasting all day
539539 sun was eclipsedRW: sun was eclipsed
540540 20/6 total solar eclipse Rome


540 Zachariah of Mitylene said that “a great and terrible comet appeared in the sky at evening time for 100 days” about A.D. 540.

ASC: This year the sun was eclipsed
541541 Plague of Justinian (541–542)RW: a comet over Gaul and great mortality just before the final battle between Arthur and Mordred
543 RW: 2 sons of Mordred killed by Constantine
544544 total solar eclipse 
545 RW: Constantine king of Britons died. Succeeded by nephew Aurelius Conan
546536-546 Tree ring growth. Volcanic winter 
547 AC: a great death. Maelgwn of Gwynedd died. Followed by yellow plague
549Annals of Ulster: A great mortality in which these rested 
552 ASC: Cynric defeats Britons at Sarum
556 ASC: Cynric defeats Britons at Beranbury
570 AC: death of Gildas
571 RW: completed one cycle of the Easter period 524 years after the crucifixion
573 AC: The battle of Arfderydd between the sons of Eliffer and Gwenddolau son of Ceidio; in which battle Gwenddolau fell; Merlin went mad.
577 ASC:  Cuthwin & Cuthu kill 3 British kings. Commail, Cordida, Farinmail at Dyrham
578 RW:  St Germanus died. Aurelus Conanus king of Britons died succeeded by Vortipore
580 RW: firey meteors. Ceaulin took Gloucester, Cirencester and Bath
AC: Conversion of Constantine
BD:  Maurice
584 RW:  Tiberius died
590Roman Plague: Death of Pope Pellagius II 
592total solar eclipse ConstantinopleAC: Augustine converts English
601 AC: Pope Greogory dies
BD:  many things are at hand which were not before, viz. changes of air, and terrors from heaven, and tempests out of the order of the seasons, wars, famines, plagues, earthquakes in several places
604Pope Gregory dies 
607Halley’s Comet


Seen for over 100 days in China.

626 AC: Edwin baptised
639639 total solar eclipseRW: Cerdic first king of Saxons dies
661661 partial solar eclipse 
664664 total solar eclipseASC: This year the sun was eclipsed, on the eleventh of May; there was a great plague in the island Britain
BD: there happened an eclipse of the sun, on the third In the same year, a sudden pestilence depopulated of men.
665 ANC: The first celebration of Easter among the Saxons. The second battle   of Badon. Morgan dies
676676-677 Japan, China, Italy – CometAC: A star of marvelous brightness was seen shining throughout the whole world
RW: Comet appeared and shone for 3 months
ASC: here the star comet appeared and shone for 3 months
BD: a comet appeared and Bishop Wifred driven from his See
680680 Roman Plague 
682 AC: A great plague in Britain, in which Cadwaladr son of Cadwallon dies
684684 AD Chinese Annals of Tang (83) Halley’s CometAC: A plague was in Ireland
686686 eclipse of the moonRW: eclipse of the moon
687687 Plague in EgyptRW: a terrible pestilence also in Rome
689 ANC: The rain turned to blood in Britain, and in Ireland milk and butter turned sour
698partial solar eclipse 
729 ASC: Anglo-Saxon Chronicle ..this year a star appeared and St. Egbert died
733733 partial solar eclipseASC: the sun was eclipsed;
734734 total lunar eclipseRW: 7 Bede died


RW: Moon suffused with blood

ASC:.  This year was the moon as if covered with blood;
735735 Death of Bede 
758758 total solar eclipse 
760760AD Chinese Annals of Tang (83) Halley’s Comet


760 eclipse of the moon

RW: eclipse of the moon
764764 partial solar eclipse 
774774–775 Carbon-14 Spike: Possile Solar flareRW: This year also appeared in the heavens a red crucifix, after sunset; the Mercians and the men of Kent fought at Otford; and wonderful serpents were seen in the land of the South-Saxons.
793 ASC: This year came dreadful fore-warnings over the land of the Northumbrians, terrifying the people most woefully: These tremendous tokens were soon followed by a great famine immense sheets of light rushing through the air, and whirlwinds, and fiery, dragons flying across the firmament.
795 ASC: This year was the moon eclipsed, between cock-crowing and dawn, on the fifth day before the calends of April
800 ASC.  This year was the moon eclipsed, at eight in the
806 ASC: here the moon grew dark on 1 September
807 ASC. This year was the sun eclipsed,
818818 partial solar eclipse 
827 ASC: This year was the moon eclipsed
837837 February 6 Halley’s Comet Annals of Tang 
838 RW: a great terrible plague
848 RW: eclipse of the sun
852852 partial solar eclipse 
878878 total solar eclipse 
879 ASC the sun goes dark
885885 total solar eclipseASC: the sun grew dark
891891 Comet observed, ChinaRW: a star appeared… some men say that in English it may be termed “hairy star”; for that there standeth off from it a long gleam of light
905905 Comet observed, ChinaASC: Here a comet appeared.
906 RW: a comet appeared for half a year.
912912 18 July, 912 Chinese Annals of the Five Dynasties (83) Halley’s Comet 
912 Annals of Ulster (a chronicle of medieval Ireland) notes in its final entry for AD 912: “A dark and rainy year.  A comet appeared. 
975 ASC:  and this year Edward, Edgar’s son, succeeded to the kingdom; and then soon, in the same year, during harvest, appeared “cometa” the star;
RW: A comet appeared followed by dreadful famine.
989989 AD Chinese Annals of Sund Halley’s Comet 
995 ASC: a comet that is haired
10661066 Halley’s CometASC: AD 1066 ASC.Then was over all England such a token seen as no man ever saw before.  Some men said that it was the comet-star, which others denominate the long-hair’d star.  It appeared first on the eve called “Litania major” that is, on the eighth before the calends off May; and so shone all the week
RW: Harold’s death predicted by large comet of bloody colour with a long train

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