It does not, however, seem probable that their apparent anti-galactic tendency has such a significance; in the Magellanic Clouds spiral nebulae are very abundant, a fact which shows that there is no essential antipathy between the stars and the spiral nebulae.

Certain stars and nebulae show a bright line helium spectrum.

Thus in 1864 the spectroscope yielded him evidence that planetary and irregular nebulae consist of luminous gas - a conclusion tending to support the nebular hypothesis of the origin of stars and planets by condensation from glowing masses of fluid material.

He arranges a selection from his observations on the nebulae in such a way as to give great plausibility to his view of the gradual transmutation of nebulae into stars Herschel begins by showing us that there are regions in the heavens where a faint diffused nebulosity is all that can be detected by the telescope.

There are other nebulae in which a nucleus can be just discerned, others again in which the nucleus is easily seen, and still others where the nucleus is a brilliant star-like point.

photographs of Nebulae; Sir Robert Ball, The Earth's Beginning.

Should any one be sceptical as to the sufficiency of these laws to account for the present state of things, science can furnish no evidence strong enough to overthrow his doubts until the sun shall be found growing smaller by actual measurement, or the nebulae be actually seen to condense into stars and systems."

By this means she detected in 1783 three remarkable nebulae, and during the eleven years 1786-1797 eight comets, five of them with unquestioned priority.

Though she returned to Hanover in 1822 she did not abandon her astronomical studies, and in 1828 she completed the reduction, to January 1800, of 2500 nebulae discovered by her brother.

He intended to follow it up with similar treatises on Mars, Jupiter, sun, moon, comets and meteors, stars, and nebulae, and had in fact commenced a monograph on Mars, when the failure of a New Zealand bank deprived him of an independence which would have enabled him to carry out his scheme without anxiety as to its commercial success or failure.

Of these the more noteworthy dealt with the distribution of stars, starclusters and nebulae, and the construction of the sidereal universe.

Owing to the famine and the disturbed state of the country, which demanded his attention as a large landowner and lieutenant of King's County (from 1831), the instrument remained unused for nearly three years, but since 1848 it has been in constant use, chiefly for observations of nebulae, for which it was particularly suited on account of its immense optical power, nominally 6000.

In the same publication for 1844 and 1850 he communicated short descriptions and drawings of some of the more interesting nebulae, and in the volume for 1861 he published a paper "On the Construction of Specula of 6-ft.

Aperture, and a Selection from the Observations of Nebulae made with them," with numerous engravings.

Among his contributions to astronomy may be noted his eleven zonecatalogues of 34,674 stars, his measurements, in 1836-1837, of nebulae and clusters, and his determination of the mass of Uranus from observations of its satellites (Mena.

Precht, Ber., 1886, 19, p. 2326), in some meteorites, in certain stars and nebulae, and also in the envelopes of the sun.

But at the same time none but the Herschels have swept the whole sky for the discovery of faint nebulae; and FIG.

(3) As a Cassegrain reflector, for photographing the moon, planets or very bright nebulae on a large scale, as shown in fig.

Doubtless with improved telescopes many more apparent nebulae would be shown to be clusters, but there are certainly many nebulae which are otherwise constituted.

This may explain the existence of gaseous nebulae, which are often found intimately associated with star-clusters, a good example being the nebulosity surrounding the Pleiades.

Spiral nebulae have the remarkable characteristic of avoiding the galactic plane, and it has been suggested that the space outside the limits of the stellar universe is filled with them.

By this means she detected in 1783 three remarkable nebulae, and during the eleven years 1786-1797 eight comets, five of them with unquestioned priority.

Aperture, and a Selection from the Observations of Nebulae made with them," with numerous engravings.

Doubtless with improved telescopes many more apparent nebulae would be shown to be clusters, but there are certainly many nebulae which are otherwise constituted.

At the present day when the nebulae that are spiral in form have been shown to be so numerous, next to the fixed stars themselves, our view of the nebular theory has been somewhat modified.

The accounts of the observations given in these papers, however, were fragmentary; but in 1879-80 a complete account of them was published by the present earl ("Observations of Nebulae and Clusters of Stars made with the 6-foot and 3-foot Reflectors at Birr Castle from 1848 to 1878") in the Scient.

Free nitrogen is also found in some natural waters and has been recognized in certain nebulae.

1808); Uranographia (1801), a collection of 20 star-maps accompanied by a catalogue of 17,240 stars and nebulae.

Educated at Trinity College, Dublin, he was appointed in 1865 assistant to the Earl of Rosse's observatory at Parsonstown, and whilst there he discovered four spiral nebulae.

The incandescent bodies are of two classes: stars and nebulae.

The stars are supposed to be generally spherical, like the sun, in form, and to have fairly well-defined boundaries; while the nebulae are generally irregular in outline and have no well-defined limits.

Charles Messier (1730-1817) had catalogued in 1781 103 nebulae; Herschel discovered 2500, laid down the lines of their classification, divined the laws of their distribution, and assigned their place in a scheme of development.

in diameter, which afforded the first indications of the spiral structure shown in recent photographs to be the most prevalent char- Lord acteristic of nebulae.

sions be secured of such faint objects as nebulae, tele scopic comets, and the immense majority of stars, or of the dim ranges of stellar and nebular spectra.

There are many lines in the spectra of the stars, as well as of the nebulae, which are not certainly identified with those belonging to any elements known to our chemistry.

The question is rather that of the infinity of forms that matter may assume, including that most attenuated form found in the nebulae, which seem to be composed of matter more refined than even the atoms supposed to make up the matter around us.

vi, of his Ephemerides, 1763); Lecons elementaires de Mathematiques (1741), frequently reprinted; ditto de Mecanique (1743), &c.; ditto d' Astronomie (146), 4th edition augmented by Lalande (1779); ditto d'Optique (1750), &c. Calculations by him of eclipses for eighteen hundred years were inserted in L' Art de verifi s r les dates (1750); he communicated to the Academy in 1755 a classed catalogue of fortytwo southern nebulae, and gave in t.

2 All the time-worn fables and conjectures regarding the composition of the Milky Way were at once dissipated by the simple statement that to the eye, reinforced by the telescope, it appeared as a congeries of lesser stars, while the great nebulae were equally declared to be resolvable into similar elements.

gaseous nebulae.

He will often stare at the cream dissolving in his coffee, forming specific nebulae, sometimes planets.

nebulae ionized by hot evolved stars.

I looked at Hubble's greatest hits: nebulae, spiral galaxies, planets, star clusters, gaseous nebulae.

Narrow bandpass filters also take out sky glow emission lines which also helps to improve the visual contrast of very faint nebulae.

Historical No-one before Hubble imagined that the spiral nebulae might be other galaxies.

In other planetary nebulae, like the Ring Nebula (NGC 6720 ), we view the donut from the top.

Bipolar lobes many planetary nebulae have a pronounced spreading along an axis.

In the ensuing 70 years, only three more planetary nebulae have been discovered in globular clusters.

reflection nebulae.

Planetary nebulae, supernovae, stellar remnants - white dwarfs, neutron stars, black holes.

spiral nebulae, in the nearby Virgo cluster of galaxies (AAO photo ).

Certain stars and nebulae show a bright line helium spectrum.

The instrumental equipment of that observatory was somewhat antiquated, his largest telescope being a small refractor of 73 lines aperture, but he selected a line of work to suit the instruments at his disposal, observing nebulae and variable stars and keeping a watch on comets and new planets.

The results of his observations of nebulae are contained in two catalogues published in the Astronomische Beobachtungen der Grossherzoglichen Sternwarte zu Mannheim, 1st and 2nd parts (1862 and 1875), and those of his variable star observations appeared in the Jahresberichte des Mannheimer Vereins fur Naturkunde, Nos.

At the present day when the nebulae that are spiral in form have been shown to be so numerous, next to the fixed stars themselves, our view of the nebular theory has been somewhat modified.

He arranges a selection from his observations on the nebulae in such a way as to give great plausibility to his view of the gradual transmutation of nebulae into stars Herschel begins by showing us that there are regions in the heavens where a faint diffused nebulosity is all that can be detected by the telescope.

There are other nebulae in which a nucleus can be just discerned, others again in which the nucleus is easily seen, and still others where the nucleus is a brilliant star-like point.

Should any one be sceptical as to the sufficiency of these laws to account for the present state of things, science can furnish no evidence strong enough to overthrow his doubts until the sun shall be found growing smaller by actual measurement, or the nebulae be actually seen to condense into stars and systems."

photographs of Nebulae; Sir Robert Ball, The Earth's Beginning.

Though she returned to Hanover in 1822 she did not abandon her astronomical studies, and in 1828 she completed the reduction, to January 1800, of 2500 nebulae discovered by her brother.

Free nitrogen is also found in some natural waters and has been recognized in certain nebulae.

Thus in 1864 the spectroscope yielded him evidence that planetary and irregular nebulae consist of luminous gas - a conclusion tending to support the nebular hypothesis of the origin of stars and planets by condensation from glowing masses of fluid material.

He intended to follow it up with similar treatises on Mars, Jupiter, sun, moon, comets and meteors, stars, and nebulae, and had in fact commenced a monograph on Mars, when the failure of a New Zealand bank deprived him of an independence which would have enabled him to carry out his scheme without anxiety as to its commercial success or failure.

Of these the more noteworthy dealt with the distribution of stars, starclusters and nebulae, and the construction of the sidereal universe.

Owing to the famine and the disturbed state of the country, which demanded his attention as a large landowner and lieutenant of King's County (from 1831), the instrument remained unused for nearly three years, but since 1848 it has been in constant use, chiefly for observations of nebulae, for which it was particularly suited on account of its immense optical power, nominally 6000.

From 1848 to 1878 it was but with few interruptions employed for observations of nebulae (see Nebula); and many previously unknown features in these objects were revealed by it, especially the similarity of "annular" and "planetary" nebulae, and the remarkable "spiral" configuration prevailing in many of the brighter nebulae.

In the same publication for 1844 and 1850 he communicated short descriptions and drawings of some of the more interesting nebulae, and in the volume for 1861 he published a paper "On the Construction of Specula of 6-ft.

The accounts of the observations given in these papers, however, were fragmentary; but in 1879-80 a complete account of them was published by the present earl ("Observations of Nebulae and Clusters of Stars made with the 6-foot and 3-foot Reflectors at Birr Castle from 1848 to 1878") in the Scient.

In that case the main branch is found to represent the new series if a' and b 1 are also put equal to zero, so that n l r I I N = 4 - y2' where r takes successively the values 1.5, 2.5, 3.5 A knowledge of the constants now determines the trunk series, which should be n I I N - (I,5)2 The least refrangible of the lines of this series should have a wavelength 4687.88, and a strong line of this wave-length has indeed been found in the spectra of stars which are made up of bright lines, as also in the spectra of some nebulae.

Among his contributions to astronomy may be noted his eleven zonecatalogues of 34,674 stars, his measurements, in 1836-1837, of nebulae and clusters, and his determination of the mass of Uranus from observations of its satellites (Mena.

Precht, Ber., 1886, 19, p. 2326), in some meteorites, in certain stars and nebulae, and also in the envelopes of the sun.

But at the same time none but the Herschels have swept the whole sky for the discovery of faint nebulae; and FIG.

(3) As a Cassegrain reflector, for photographing the moon, planets or very bright nebulae on a large scale, as shown in fig.

This may explain the existence of gaseous nebulae, which are often found intimately associated with star-clusters, a good example being the nebulosity surrounding the Pleiades.

Spiral nebulae have the remarkable characteristic of avoiding the galactic plane, and it has been suggested that the space outside the limits of the stellar universe is filled with them.

It does not, however, seem probable that their apparent anti-galactic tendency has such a significance; in the Magellanic Clouds spiral nebulae are very abundant, a fact which shows that there is no essential antipathy between the stars and the spiral nebulae.

1808); Uranographia (1801), a collection of 20 star-maps accompanied by a catalogue of 17,240 stars and nebulae.

Educated at Trinity College, Dublin, he was appointed in 1865 assistant to the Earl of Rosse's observatory at Parsonstown, and whilst there he discovered four spiral nebulae.

The incandescent bodies are of two classes: stars and nebulae.

The stars are supposed to be generally spherical, like the sun, in form, and to have fairly well-defined boundaries; while the nebulae are generally irregular in outline and have no well-defined limits.

Charles Messier (1730-1817) had catalogued in 1781 103 nebulae; Herschel discovered 2500, laid down the lines of their classification, divined the laws of their distribution, and assigned their place in a scheme of development.

in diameter, which afforded the first indications of the spiral structure shown in recent photographs to be the most prevalent char- Lord acteristic of nebulae.

sions be secured of such faint objects as nebulae, tele scopic comets, and the immense majority of stars, or of the dim ranges of stellar and nebular spectra.

There are many lines in the spectra of the stars, as well as of the nebulae, which are not certainly identified with those belonging to any elements known to our chemistry.

The question is rather that of the infinity of forms that matter may assume, including that most attenuated form found in the nebulae, which seem to be composed of matter more refined than even the atoms supposed to make up the matter around us.

vi, of his Ephemerides, 1763); Lecons elementaires de Mathematiques (1741), frequently reprinted; ditto de Mecanique (1743), &c.; ditto d' Astronomie (146), 4th edition augmented by Lalande (1779); ditto d'Optique (1750), &c. Calculations by him of eclipses for eighteen hundred years were inserted in L' Art de verifi s r les dates (1750); he communicated to the Academy in 1755 a classed catalogue of fortytwo southern nebulae, and gave in t.

2 All the time-worn fables and conjectures regarding the composition of the Milky Way were at once dissipated by the simple statement that to the eye, reinforced by the telescope, it appeared as a congeries of lesser stars, while the great nebulae were equally declared to be resolvable into similar elements.

The nebulae IC 432 and NGC 2023 appear as small blue reflection nebulae.

Planetary nebulae, supernovae, stellar remnants - white dwarfs, neutron stars, black holes.

M100, one of the spiral nebulae, in the nearby Virgo cluster of galaxies (AAO photo).