Glossary term: Irregular Galaxy
Description: An irregular galaxy is a type of galaxy with little or no symmetry (it has a distorted morphology or shape). They are typically smaller than spiral and elliptical galaxies, and they often contain significant amounts of star-forming gas. The Large and Small Magellanic Clouds are irregular galaxies, relatively close (approximately 160,000 light years, and 200,000 light years) to our Milky Way galaxy, that can be observed from Earth's southern hemisphere with the unaided eye.
Related Terms:
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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
If you notice a factual error in this glossary definition then please get in touch.
In Other Languages
- Arabic: المجرة غير المنتظمة
- Bengali: নৈমিত্তিক ছায়াপথ
- German: Irreguläre Galaxie
- French: Galaxie irrégulière
- Italian: Galassia irregolare
- Japanese: 不規則銀河 (external link)
- Korean: 불규칙은하
- Brazilian Portuguese: Galáxia Irregular
- Simplified Chinese: 不规则星系
- Traditional Chinese: 不規則星系
Related Media
NGC 5264 - An irregular island
Caption: The dwarf irregular galaxy NGC 5264 is located 15 million light years away. It is only about 11,000 light years across, much smaller than our Milky Way, and consists of approximately a billion stars. It lacks the spiral structure of our home Galaxy. The small blue patches in NGC 5264 mark groups of young hot blue stars. This suggests that stars formation in this galaxy is still on-going.
Credit: ESA/Hubble and NASA
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License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Related Diagrams
Sculptor Constellation Map
Caption: The constellation Sculptor with its brighter stars and surrounding constellations. Sculptor is surrounded by (going clockwise from the top): Cetus, Aquarius, Piscis Austrinus, Grus, Phoenix and Fornax.
Sculptor is a southern constellation and thus the whole constellation is visible at some point in the year throughout the southern hemisphere. The whole constellation is also visible in equatorial and most temperate regions of the northern hemisphere. Parts of the constellation are also visible to the remaining northern temperate regions. Sculptor is best viewed in the evening in the late northern hemisphere autumn and late southern hemisphere spring.
The irregular galaxy NGC 55, and the spiral galaxies NGC 253 and NGC 300 all lie in Sculptor. There are marked here with red ellipses.
The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons



