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''De Stella Nova in Pede Serpentarii'' (On the New Star in the Foot of the Serpent Handler), generally known as ''De Stella Nova'' was a book written by Johannes Kepler between 1605 and 1606, when the book was published in
Prague Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...
. Kepler wrote the book following the appearance of the supernova
SN 1604 SN 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Type Ia supernova that occurred in the Milky Way, in the constellation Ophiuchus. Appearing in 1604, it is the most recent supernova in the Milky Way galaxy to hav ...
, also known as
Kepler's Supernova SN 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Type Ia supernova that occurred in the Milky Way, in the constellation Ophiuchus. Appearing in 1604, it is the most recent supernova in the Milky Way galaxy to hav ...
. This star appeared in the constellation
Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constell ...
, the Greek (Ὀφιοῦχος Ophioukhos) "serpent-bearer" which is also known in Latin as Serpentarius . The
SN 1604 SN 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Type Ia supernova that occurred in the Milky Way, in the constellation Ophiuchus. Appearing in 1604, it is the most recent supernova in the Milky Way galaxy to hav ...
supernova was observable for almost a year, from October 1604 to October 1605. Observation conditions were good, particularly when it was first visible. A conjunction of Jupiter and Mars happened to be taking place near the place where the supernova appeared, meaning that astronomers happened to be looking in its direction. As a result there were many witnesses to its appearance, but Kepler's observations were particularly meticulous. The care he took not only to record his own observations but to compile the observations of other astronomers make ''De Stella Nova'' a very important record both of the supernova itself, and of the astronomy of the early 17th century.


Position

As soon as the ‘new star’ appeared, Kepler began recording his observations, measuring its angular distance from known stars such as σ Sagittarii, η Ophiuchi, α Ophiuchi, ζ Ophiuchi, α Aquilae and α Scorpii. With a typical error of less than one
minute of arc A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
, remarkable for observations made with the naked eye, he established that it had no noticeable movement. The low
declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of t ...
of the supernova over the
latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north po ...
Kepler was observing from (Prague, around 50° north) likely caused
atmospheric refraction Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. This refraction is due to the velocity of ligh ...
, explaining most of Kepler’s errors. It is hard to be sure however, since Kepler’s book gives no indication of the times or atmospheric conditions of his observations. Kepler also mentions the measurements made by
David Fabricius David Fabricius (9 March 1564 – 7 May 1617) was a German pastor who made two major discoveries in the early days of telescopic astronomy, jointly with his eldest son, Johannes Fabricius (1587–1615). David Fabricius (Latinization of his proper n ...
in Osteel, which agreed with his own. (They were so precise that in 1943 they allowed
Walter Baade Wilhelm Heinrich Walter Baade (March 24, 1893 – June 25, 1960) was a German astronomer who worked in the United States from 1931 to 1959. Biography The son of a teacher, Baade finished school in 1912. He then studied maths, physics and astro ...
to locate the
supernova remnant A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar ma ...
, SNR G4.5+6.8). Kepler’s measurements allowed him to be certain that the ‘new star’ showed no
parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
. Thus, as suggested by the supernova observed 32 years previously by
Tycho Brahe Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was ...
(
SN 1572 SN 1572 (''Tycho's Supernova'', ''Tycho's Nova''), or B Cassiopeiae (B Cas), was a supernova of Type Ia in the constellation Cassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 ...
), the Aristotelian doctrine that the distant stars were fixed in the
firmament In biblical cosmology, the firmament is the vast solid dome created by God during his creation of the world to divide the primal sea into upper and lower portions so that the dry land could appear. The concept was adopted into the subsequent ...
must be false.


Light curve

Kepler also mentioned his measures of the object’s brightness, which compared it with
Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandt ...
,
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
,
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
and several nearby stars. These were sufficiently precise and extended over a year, allowing the supernova’s light curve to be reconstructed.


References


External links

* {{Authority control Works by Johannes Kepler 1606 books 1606 in the Holy Roman Empire 17th-century Latin books