A galaxy refers to a huge system of stars, planets, gas, and dust that are gravitationally bound together. Our solar system, for instance, is part of the Milky Way galaxy, which is thought to contain more than 100 billion other stars, and according to current estimates, the universe in its entirety is thought to contain upwards of two trillion different galaxies.
Most galaxies fall into well-defined classifications and are either spiral-shaped like the Milky Way galaxy, elliptical galaxies, or irregular-shaped galaxies. However, some galaxies defy all attempts at classification. While some strange and bizarre galaxies are the result of gravitational interactions with other more massive, and sometimes less massive objects, they all have one thing in common; they look more like artists’ impressions than real, tangible collections of billions of stars.
Take a look at the stunning photos below of some of the strangest galaxies in the universe.
10 Weirdest Galaxies in the Universe
The Black Eye Galaxy (M64)
- Type: Spiral Galaxy
- Constellation: Coma Berenices
If it is possible for a galaxy to take on an evil aspect, M64 does it perfectly. Although colorful galaxies are plentiful, this one is strongly reminiscent of the garish pulp science-fiction magazine covers of the 1950s. The red color is derived from hydrogen, which means new stars are being formed in very large numbers. But what is really strange is that the galaxy contains two counter-rotating systems. The gas in the outer regions rotates in the opposite direction to the gas and stars in the inner regions, extending to a distance of about 40,000 light-years.
At a distance of about 17 million light-years from Earth, it is of course difficult to tell, but this unusual rotation may be the result of a merger between M64 and a smaller satellite galaxy more than a billion years ago.
The Southern Pinwheel (M83)
- Type: Barred Spiral Galaxy
- Constellation: Hydra
There are many beautiful galaxies in the Universe, but this one, also known as M83, is among the most beautiful, even if beauty is only in the eye of the beholder. What makes this galaxy particularly interesting is its high rate of star formation and the large number of supernova remnants that have been identified within it.
The huge number of active star-forming regions can be seen as pink areas scattered through the galaxy. Their glow is produced as ultraviolet radiation from hot young stars ionizes the surrounding clouds of hydrogen gas.
Sombrero Galaxy (M104)
- Type: Spiral Galaxy
- Constellation: Virgo
The Sombrero Galaxy is famous for its enormous central bulge and the prominent dark lane of dust that cuts across its bright stellar disk. Seen almost edge-on from Earth, the combination gives the galaxy its unmistakable hat-like appearance.
The Sombrero is also surrounded by an unusually rich population of globular star clusters. Hubble observations have revealed hundreds of these ancient clusters around the galaxy, making M104 particularly useful for studying the early history of galaxies.
Centaurus A (NGC 5128)
- Type: Peculiar Elliptical / Active Galaxy
- Constellation: Centaurus
Centaurus A is one of the strangest large galaxies in the nearby universe. Its smooth elliptical population of stars is crossed by a spectacular warped lane of gas and dust, giving the galaxy an appearance unlike that of a normal elliptical.
The unusual structure is thought to be the legacy of a merger with a smaller gas-rich galaxy. Hubble’s view, extending from ultraviolet through near-infrared wavelengths, reveals dark dust clouds alongside glowing regions where new stars are forming. Deep within Centaurus A is an active supermassive black hole that makes the galaxy one of the strongest radio sources in the sky.
NGC 474
- Type: Elliptical / Lenticular Galaxy
- Constellation: Pisces
If the Southern Pinwheel Galaxy represents the familiar symmetry of a spiral galaxy, NGC 474 is something very different. Surrounding its bright central body are enormous faint shells and tidal structures composed of hundreds of millions of stars.
These ghostly structures are thought to be the remains of past mergers or close interactions with smaller galaxies. Some extend far beyond the main body of NGC 474, preserving a visible record of the galaxy’s turbulent history.
Arp 87 (NGC 3808/NGC 3808A)
- Type: Interacting Galaxies
- Constellation: Leo
The interaction between the two galaxies that make up Arp 87 has distorted both of their shapes. NGC 3808, the larger face-on spiral, has drawn out a stream of stars, gas, and dust that wraps toward its smaller companion, NGC 3808A.
The two galaxies are connected by a bridge of material produced by their gravitational interaction. NGC 3808A also has a ring of stars and gas oriented almost perpendicular to its main disk, adding another unusual feature to this already peculiar galactic pair.
Antennae Galaxies (NGC 4038/NGC 4039)
- Type: Interacting Galaxies
- Constellation: Corvus
This is another spectacular example of a merger on a galactic scale. The two bright yellow-orange regions are the cores of the original spiral galaxies, while their interaction has compressed huge clouds of gas and triggered intense bursts of new star formation.
Many of the young star clusters created during the collision will eventually disperse, although some of the most massive may survive to become globular clusters. Wide-field views reveal the enormous tidal tails that give the Antennae Galaxies their name.
The Porpoise Galaxy (Arp 142)
- Type: Interacting Galaxies
- Constellation: Hydra
This galaxy pair is physics become art. The distorted spiral galaxy NGC 2936 has been stretched and twisted by its interaction with the elliptical galaxy NGC 2937. Older images inspired the nickname “Porpoise Galaxy,” while the dramatically distorted spiral is now also widely known as the Penguin, with its companion nicknamed the Egg.
The strange shape is temporary on cosmic timescales. Gravity continues to alter the two galaxies as their interaction proceeds, while compressed gas within NGC 2936 fuels new star formation.
NGC 660
- Type: Polar-ring Galaxy
- Constellation: Pisces
NGC 660 is a striking example of a polar-ring galaxy. Its unusual outer ring of stars and gas is inclined steeply relative to the galaxy’s main disk, producing a structure unlike that of an ordinary spiral galaxy.
One likely explanation is that NGC 660 acquired material during a past interaction or merger with another galaxy. Polar-ring galaxies are particularly interesting to astronomers because the motion of material in two very different planes can provide clues about the distribution of otherwise invisible dark matter around a galaxy.
Hoag’s Object (PGC 54559)
- Type: Ring Galaxy
- Constellation: Serpens
When astronomer Arthur Hoag discovered this object in 1950, its extraordinary appearance raised the question of whether it was really one galaxy or two. A nearly perfect ring dominated by young blue stars surrounds a yellow central region populated mainly by older stars, with an apparently dark gap separating them.
How Hoag’s Object acquired this remarkable structure is still not completely understood. The galaxy measures roughly 120,000 light-years across and lies about 600 million light-years from Earth. Adding another curiosity to the image, a much more distant ring galaxy can be seen through the gap in Hoag’s Object.