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The Way to the Stars: Build Your Own Astrolabe

Thomas Betson of Syon

Thomas Betson (d. 1516) was a religious author and librarian. He was a deacon at Syon Abbey in Middlesex from 1481 until his death, and served as the Abbey's librarian. The Abbey had one of the largest libraries in England at that time.

Although he was mainly a religious thinker and author, Betson had a very wide range of interests. This can be seen in one of his personal notebooks, which is preserved in the St John's College Library as manuscript E.6. As well as religious texts, this notebook contains handwritten notes on legal matters, an alphabet of runes, lists of herbs, medicinal recipes, and two diagrams of the night sky.

Betson's sky diagrams cover the northern and southern skies, and appear to have been copied from another source, perhaps for his own use when stargazing. A copy of the map of the northern sky is shown below. The handwriting is not easy to read, and the original is very small, so an anotated version is also provided, along with a glossary explaining some of the words used.

Click on any image to see a larger version.

A page from Thomas Betson's notebook, MS E.6, showing a sketched diagram of the northern sky

The top-right-hand quadrant of Betson's star mapThe top-left-hand quadrant of Betson's star mapThe bottom-left-right-hand quadrant of Betson's star mapThe bottom-right-hand quadrant of Betson's star map

aldebaran

Aldebaran is the brightest star in the constellation of Taurus, and one of the brightest stars in the sky. Its name is derived from Arabic, and means "the follower", as it appears to follow the Pleiades across the sky.

alfeca

The star Alphecca is the brightest star in the constellation Corona Borealis, the Northern Crown. Betson has drawn the crown on his diagram above this label.

algol

Algol is a star in the constellation Perseus. Its name is derived from the Arabic for "the head of the ogre" and it is also known as the Demon Star.

alhaiot

Alhajoth is another name for the star Capella, the brightest star in the constellation Auriga and the third brightest star in the northern sky.

altanin

Eltanin is the brightest star in the constellation Draco.

althaire

Altair is the brightest star in the constellation of Aquila, the eagle. It is one third of the Summer Triangle formed with Deneb and Vega.

andromeda

The constellation Andromeda represents a princess from the Greek legend of Perseus. Within the bounds of this constellation can be seen the Andromeda galaxy, the nearest spiral galaxy to our own Milky Way.

aquarius

The water carrier. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

aries

The ram. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

auriga

The constellation of Auriga takes the shape of a charioteer. Its brightest star is Capella.

[Boötes]

The large man drawn across the diagram is the constellation of Boötes, the Ploughman.

cancer

The crab. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

capricornus

The goat. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

cassiepia

The constellation of Cassiopeia has a distinctive 'w'-shape when seen in the night sky. It is said to represent the mythological Ethiopian Queen of the same name.

cauda

"The tail", this may refer to the constellation of Serpens, the Snake. This constellation is in two distinct parts, split in two by the constellation of Ophiuchus. Betson has here drawn a two-headed snake, and marked "cauda" (tail), where the head is today said to be.

cauda draconis

The Tail of the Dragon. The constellation Draco, the Dragon, snakes a long way across the sky, as shown by the curved line drawn all around the centre of Betson's diagram.

cor. Scorp.

The star Cor Scorpii, the Heart of the Scorpion, is also known as Antares. It is the brightest star in the constellation Scorpio.

cornu ariets

Cornu Artietis, the Horn of the Ram, is the brightest star in the small constellation Aries, the Ram. One of its traditional names is El Nath, derived from the Arabic for "the butting [horn]", and shared with Cornu Tauri.

cornu tauri

Cornu Tauri, the Horn of the Bull, is the second brightest star in the constellation Taurus, the Bull. One of its traditional names is El Nath, derived from the Arabic for "the butting [horn]", and shared with Cornu Arietis.

delphinus

The constellation of Delphinus, the Dolphin. Betson has drawn in the principal seven stars.

draco

The constellation Draco, the Dragon, snakes a long way across the sky, as shown by the curved line drawn all around the centre of Betson's diagram, ending in a curled tail.

gallina

Gallina is one of the traditional names of the star commonly known as Deneb, the brightest star in the constellation of Cygnus, the Swan. It is one third of the Summer Triangle formed with Altair and Vega.

gemini

The twins. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

hercules

The constellation Hercules is named after the mythological Roman hero.

leo

The lion. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

libra

The scales. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

nautica

The star labelled "nautica" is in the position of the Pole Star, a star which is located almost exactly on the north celestial pole. Nautica (meaning "nautical" or "to do with ships" in Latin) is an unusual name for this star, but it may refer to its usefulness as a navigational aid for sailors.

[Ophiuchus]

The constellation of Ophiuchus is said to be a man holding the body of the Snake, and cutting that constellation into two parts. This visualization can be seen in Betson's drawing.

pegasus equus

The mythological flying horse Pegasus is represented in the skies by the constellation of the same name.

pisces

The fish. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

[Pleiades]

The Pleiades are a cluster of seven stars very close together, also known as the Seven Sisters. Betson has marked seven dots to show the stars, but has not named them.

polus mundi arcticus

"The north pole of the world". This caption marks the place of the north star, the point around with the stars appear to rotate for observers in the northern hemisphere.

sagittarius

The archer. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

scorpio

The scorpion. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

[Serpens]

The constellation of Serpens, the Snake, is in two distinct parts, split in two by the constellation of Ophiuchus. Betson has drawn a two-headed snake. The head of the snake is today said to be on the right, where has Betson has, in fact, marked "tail".

spica

Spica is the brightest star in the constellation Virgo. Its name is derived from the Latin "spica virginis", meaning "Virgo's ear of grain".

taurus

The bull. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

triagla

The constellation Triangulum is very small, and has three principal stars found in the shape of a triangle.

ursa ma.

The constellation of Ursa Major, the Great Bear. The main stars have been drawn in.

ursa mi.

The constellation of Ursa Minor, the Little Bear. The main stars have been drawn in, pointing towards the north celestial pole.

virgo

The young maid. One of the twelve constellations of the Zodiac, the path followed by the sun through the sky.

wega

Vega is the brightest star in the constellation Lyra, the Lyre, and the second brightest star in the northern sky. It is one third of the Summer Triangle formed with Altair and Deneb.




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