The skiff was headed for the very center of the nebula -- toward that place which, Jack knew now, could hold nothing less important than the very core of the Angel's life and religion.

The Blue Planetary was discovered by John Herschel and named for its color's similarity to Uranus, though the nebula is three times larger than the planet.

Originally, nebula was a name for any extended astronomical object, including galaxies beyond the Milky Way.

The first true nebula, as distinct from a star cluster, was mentioned by the Arabic / Muslim astronomer, Abd al-Rahman al-Sufi, in his Book of Fixed Stars ( 964 ).

This nebula was also observed by Johann Baptist Cysat in 1618.

A third category was added in 1912 when Vesto Slipher showed that the spectrum of the nebula that surrounded the star Merope matched the spectra of the Pleiades open cluster.

( At that time, nebula was the generic term for any visually extended or diffuse astronomical object, including galaxies beyond the Milky Way, until galaxies were confirmed as extragalactic systems by Edwin Hubble in 1924.

The first planetary nebula discovered was the Dumbbell Nebula in the constellation of Vulpecula, observed by Charles Messier in 1764 and listed as M27 in his catalogue of nebulous objects.

On August 29, 1864, Huggins was the first to take the spectrum of a planetary nebula when he analyzed NGC 6543.

His drawing, the first such known of the Orion nebula, was published in Systema Saturnium in 1659.

* 1054 — Chinese and Arab astronomers observe the SN 1054, responsible for the creation of the Crab Nebula, the only nebula whose creation was observed

A well known example of such a nebula is the Crab Nebula, left over from a supernova that was observed in China and North America in 1054.

The nebula was observed by John Bevis in 1731 ; it corresponds to a bright supernova recorded by Arab, Chinese and Japanese astronomers in 1054.

The nebula was the first astronomical object identified with a historical supernova explosion.

In the 1950s and 1960s, the Sun's corona was mapped from observations of the Crab's radio waves passing through it, and in 2003, the thickness of the atmosphere of Saturn's moon Titan was measured as it blocked out X-rays from the nebula.

The nebula was independently rediscovered in 1758 by Charles Messier as he was observing a bright comet.

In the early 20th century, the analysis of early photographs of the nebula taken several years apart revealed that it was expanding.

In the 1960s it was found that the source of the electrons ' curved paths was the strong magnetic field produced by a neutron star at the center of the nebula.

Observers used the Chandra X-ray Observatory to observe Saturn's moon Titan as it crossed the nebula, and found that Titan's X-ray ' shadow ' was larger than its solid surface, due to absorption of X-rays in its atmosphere.

This nebula was discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779, who reported that it was "... as large as Jupiter and resembles a planet which is fading.

Messier and German-born astronomer William Herschel speculated that the nebula was formed by multiple faint stars that were unresolvable with his telescope.

" Later the same month, fellow French astronomer Charles Messier independently found the same nebula while searching for comets.

The suggestion that pulsars were rotating neutron stars was put forth independently by Thomas Gold and Franco Pacini in 1968, and was soon proven beyond reasonable doubt by the discovery of a pulsar with a very short ( 33-millisecond ) pulse period in the Crab nebula.

William Herschel observed the Crab nebula numerous times between 1783 and 1809, but we do not know whether he was aware of its existence in 1783, or if he discovered it independently of Messier and Bevis.

In 1912 Vesto Slipher measured the first Doppler shift of a " spiral nebula " ( spiral nebula is the obsolete term for spiral galaxies ), and soon discovered that almost all such nebulae were receding from Earth.

To early observers with low-resolution telescopes, M27 and subsequently discovered planetary nebulae somewhat resembled the giant planets like Uranus, and William Herschel, discoverer of this planet, eventually coined the term ' planetary nebula ' for them, although, as we now know, they are very different from planets.

However, there has yet to be an established case of a planetary nebula discovered in an open cluster as based on a consistent set of distances, reddenings, and radial velocities.

In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier.

In 1902, Vogel and Eberhard discovered differing velocities within the nebula and by 1914 astronomers at Marseilles had used the interferometer to detect rotation and irregular motions.

The Helix Nebula was the first planetary nebula discovered to contain cometary knots.

* NGC 1499: Also called California Nebula this emission nebula, discovered in 1884-85 by the American astronomer Edward E. Barnard, is a great target for astrophotographers.

The Dumbbell Nebula ( M27 ), is a large, bright planetary nebula which was discovered by the French astronomer Charles Messier in 1764 as the very first object of its kind.

In 1888, Mrs. Fleming discovered the Horsehead nebula on Harvard plate B2312, describing the bright nebula ( later known as IC-434 ) as having " a semicircular indentation 5 minutes in diameter 30 minutes south of Zeta.

* The nebula NGC 7538 is home to the largest yet discovered protostar.

In early 2007, scientists using the Spitzer discovered evidence that potentially indicates that the Pillars were destroyed by a nearby supernova explosion about 6, 000 years ago, but the light showing the new shape of the nebula will not reach Earth for another millennium.

This object was the first planetary nebula to be discovered ; by Charles Messier in 1764.

Two-photon emission in that planetary nebula and a remarkable star cluster in Auriga were also discovered.

The nebula was discovered by William Herschel on October 24, 1786, from Slough, England.

The nebula was discovered by William Herschel on January 17, 1787, in Slough, England.

Minkowski 2-9, abbreviated M2-9 ( and also known as Minkowski's Butterfly, the Wings of a Butterfly Nebula or just Butterfly Nebula, and Twin Jet Nebula ) is a planetary nebula that was discovered by Rudolph Minkowski in 1947.

* In 1850, Brorsen ( re -) discovered an emission nebula in the constellation Orion, NGC 2024, also known as Flame Nebula, which had already been observed, however, by William Herschel in 1786, as we know today.

He discovered what are now known as the Messier objects M32, M36 and M38, as well as the nebulosity in M8, and he was the first to catalogue the dark nebula sometimes known as Le Gentil 3 ( in the constellation Cygnus ).

To this end, a standard candle measurement for Cepheid variables was discovered by Henrietta Swan Leavitt in 1908 which would provide Edwin Hubble with the rung on the cosmic distance ladder he would need to determine the distance to spiral nebula.