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.

In 1924 Edwin Hubble's measurement of the great distance to the nearest spiral nebulae showed that these systems were indeed other galaxies.

* Ionization cone, cones of material extending out from spiral galaxies

Hubble showed that the spiral nebulae were galaxies by determining their distances using measurements of the brightness of Cepheid variable stars.

Astronomers posit that its dust lanes, not common in elliptical galaxies, are due to a previous merger with another galaxy, probably a spiral galaxy.

One of the more significant galaxies in Canes Venatici is the Whirlpool Galaxy ( M51, NGC 5194 ) and NGC 5195, a small barred spiral galaxy that is seen face on.

Other notable spiral galaxies in Canes Venatici are the Sunflower Galaxy ( M63, NGC 5055 ), M94 ( NGC 4736 ), and M106 ( NGC 4258 ).

Then, in the late 1960s and early 1970s, Vera Rubin, a young astronomer at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, presented findings based on a new sensitive spectrograph that could measure the velocity curve of edge-on spiral galaxies to a greater degree of accuracy than had ever before been achieved.

Together with fellow staff-member Kent Ford, Rubin announced at a 1975 meeting of the American Astronomical Society the discovery that most stars in spiral galaxies orbit at roughly the same speed, which implied that their mass densities were uniform well beyond the locations with most of the stars ( the galactic bulge ), a result independently found in 1978.

Galaxies come in a variety of shapes, from round, featureless elliptical galaxies to the pancake-flat spiral galaxies.

These groups divide into blue star-forming galaxies that are more like spiral types, and red nonstar forming galaxies that are more like elliptical galaxies.

The key properties of disk galaxies, which are also commonly called spiral galaxies, is that they are very thin, rotate rapidly, and often show spiral structure.

He became a proponent of the so-called " island universes " hypothesis, which holds that spiral nebulae are actually independent galaxies.

They can grow to enormous sizes ( compared to spiral galaxies, for example ), and giant elliptical galaxies are often found near the core of large galaxy clusters.

In the Hubble classification scheme, spiral galaxies are listed as type S, followed by a letter ( a, b, or c ) that indicates the degree of tightness of the spiral arms and the size of the central bulge.

Of these, the brightest is Messier 77 ( NGC 1068 ), a 9th magnitude spiral galaxy near Delta Ceti.

An image of Messier 101 a prototypical spiral galaxy seen face-on.

Several bright galaxies are found in Ursa Major, including the pair Messier 81 ( one of the brightest galaxies in the sky ) and Messier 82 above the bear's head, and Pinwheel Galaxy ( M101 ), a spiral northeast of η Ursae Majoris.

* October 13 – French astronomer Charles Messier discovers the Whirlpool Galaxy, an interacting, grand-design spiral galaxy located at a distance of approximately 23 million light-years in the constellation Canes Venatici.

The Pinwheel Galaxy ( Messier 101 / NGC 5457 ): a spiral galaxy classified as type Scd on the Hubble sequence

* Messier 31 ( M31 ), a spiral galaxy also called the Andromeda Galaxy

Messier 100 ( also known as NGC 4321 ) is an example of a grand design spiral galaxy located within the southern part of constellation Coma Berenices.

Messier 100 is considered an starburst galaxy, with it concentrated within a ring-actually two tightly wound spiral arms attached to a small nuclear bar with a radius of 1 kilo-parsec -, where star formation has been taking place since at least 500 million years ago in separate bursts.

A GALEX image of the spiral galaxy Messier 81 in ultraviolet light.

An example of a spiral galaxy, the Pinwheel Galaxy ( also known as Messier 101 or NGC 5457 )

Unlike a disk-shaped spiral galaxy, Messier 87 has no distinctive dust lanes and it has an almost featureless, ellipsoidal shape that diminishes in luminosity with distance from the center.

In 1918, American astronomer Heber Curtis of Lick Observatory observed that there was no spiral structure in Messier 87 and he noticed a " curious straight ray ... apparently connected with the nucleus by a thin line of matter.

American astronomer Edwin Hubble categorized Messier 87 as one of the brighter globular nebulae, as it lacked any spiral structure but appeared to belong to the same family of non-galactic nebulae as spiral nebulae.

* Messier 101, or the Pinwheel Galaxy, a spiral galaxy in the constellation Ursa Major

Messier 83 ( also known as the Southern Pinwheel Galaxy, M83 or NGC 5236 ) is a barred spiral galaxy approximately 15 million light-years away in the constellation Hydra.

* Messier 74, a spiral galaxy in the constellation Pisces

* Messier 90 ( M90 ), a spiral galaxy in the Virgo cluster

* Messier 65, a spiral galaxy in the constellation Leo

* Messier 61 ( M61 ), a spiral galaxy in the Virgo Cluster

Messier 61 ( also known as M61 or NGC 4303 ) is a spiral galaxy in the Virgo Cluster.

* Messier object M88, a magnitude 11. 0 spiral galaxy in the constellation Coma Berenices

Messier 108 ( also known as NGC 3556 ) is a barred spiral galaxy in the constellation Ursa Major.

* Messier 108, a spiral galaxy in the constellation Ursa Major

* Messier 109 ( M109 ), a spiral galaxy in the constellation Ursa Major

Messier 109 ( also known as NGC 3992 ) is a barred spiral galaxy approximately away in the constellation Ursa Major.

They are more or less rhizomatous, with spiral leaves and an inflorescence that may form a raceme or a spike.

The shells of abalones have a low and open spiral structure, and are characterized by several open respiratory pores in a row near the shell's outer edge.

E. tenera are spiral freshwater gastropods having elongated, spiral shells composed of many whorls.

In the market marble columns are decorated with spiral ornaments ; there are huge paved precincts.

Both sexes have heavy spiral horns — those of the male are longer and more massive.

Some of the synapomorphies of the order are: leaves in spiral, secondary veins palmated, calyx or perianth valvate, elevated stomatal calyx / perianth with separate styles.

Furthermore, the large elliptical galaxy and the edge-on spiral galaxy, both of which have active nuclei, are connected by a stream of stars and dust, indicating that they too are interacting.

They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral or ribbon shaped in different species.

The polycarbonate disc contains a spiral groove, called the " pregroove " ( because it is molded in before data are written to the disc ), to guide the laser beam upon writing and reading information.

Multilayer coils have the problem of interlayer capacitance, so when multiple layers are needed the shape needs to be radically changed to a short coil with many layers so that the voltage between consecutive layers is smaller ( making them more spiral like ).

Actual deflation was prevented because supply shocks are not the only cause of inflation ; in terms of the modern triangle model of inflation, supply-driven deflation was counteracted by demand-pull inflation and built-in inflation resulting from adaptive expectations and the price / wage spiral.

They are generally made from whole potatoes that are cut using a specialized spiral slicer.

Tornado fries are made by skewering the whole potato, and then cutting with a specialized spiral slicer.

The zones are assigned in a spiral form starting in downtown Guatemala city.