Hubble image of Arp 189, also known as NGC 4651 or the Umbrella Galaxy. While not visible in this image, NGC 4651 was included in the Arp catalog because of a narrow stellar stream in its outskirts, the remnants of a small galaxy. Credit: ESA, NASA, D. Leonard Source

Hubble image of Arp 321, also known as Hickson 40. This group of galaxies include three spiral galaxies, an elliptical galaxy, and a lenticular (lens-like) galaxy. Credit: NASA, ESA, STScI, A. Pagan Source

Hubble and NuStar image of Arp 299, also known as NGC 3690. NuSTAR data overlaid on a Hubble image of the interacting galaxy pair show the galaxy on the right has an active supermassive black hole, glowing brightly in X-rays. Credit: NASA, JPL-Caltech, GSFC Source

Hubble Space Telescope image of Arp 18, also known as NGC 4088. NGC 4088 is an asymmetric spiral galaxy, located about 40 million light years away. Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons Source

Hubble image of Arp 78, also known as NGC 772. The cropped view does not show the galaxy's overdeveloped spiral arm, caused by interactions with a companion, which led to its inclusion in Arp's catalog of peculiar galaxies. Credit: ESA, NASA, A. Seth et al. Source

Image of Arp 91, also known as NGC 5953 and NGC 5954, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Large, high surface brightness companions. A tidal tail connects the pair. Source

JWST MIRI image of Arp 107, also known as UGC 5984. In this pair of interacting galaxies, only the one-armed spiral glows brightly in mid-infrared light. Young, forming stars surrounded by dusty silicates and soot-like molecules glow in blue. Credit: NASA, ESA, CSA, STSc Source

Spitzer image of Arp 82, also known as NGC 2535 and NGC 2536. The larger galaxy's inner arms have evenly spaced "beads on a string" star clusters, likely created by recent gravitational interactions that led to a burst of star formation. Credit: NASA, JPL-Caltech, M. Hancock Source

VLT image of Arp 16, also known as M66. M66 is a face-on spiral galaxy with a weak bar feature, seen in yellow, and loosely wound arms that are full of young, blue star clusters. Credit: ESO, P. Barthel Source

Hubble Space Telescope image of Arp 26, also known as M101 or the Pinwheel Galaxy. The image is made from 51 individual Hubble exposures, plus data from the Canada-France-Hawaii Telescope and Kitt Peak National Observatory. Credit: NASA, ESA, STScI; CFHT, NOAO, AURA, NSF Source

Hubble Space Telescope image of Arp 26, also known as M101 or the Pinwheel Galaxy. This image shows a section of the galaxy, with over 3000 bright clusters of hot, young, blue stars. Credit: NASA, ESA Source

Hubble and Spitzer image of Arp 148, also known as Mayall's Object. The white inset shows a section of the galaxy from specially-processed Spitzer data. It reveals the infrared light from a dust-obscured supernova. Credit: NASA, JPL-Caltech, STScI Source

Hubble image of Arp 182, also known as NGC 7674 and NGC 7674A. NGC 7674 is the largest of the four galaxies in the Hickson 96 compact group. Tidal interactions with its companions created the long, narrow streamers to the left and below the galaxy. Credit: NASA, ESA, STScI Source

Gran Telescopio Canarias image of Arp 30, also known as NGC 6365. Arp thought this was one galaxy with a particularly beefy arm. Later images show this is actually a pair of interacting galaxies, with one galaxy viewed face-on and one viewed nearly edge-on. Credit: GTC, IAC Source

Image of Arp 3, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Low surface brightness. Source

Hubble image of Arp 300, also known as UGC 05028 and UGC 05029. UGC 05028 (smaller spiral) and UGC 05029 (larger spiral) form an interacting galaxy pair. The bright knot in UGC 05028 may be another small galaxy. Credit: NASA, ESA, STScI, J. Dalcanton, Judy Schmidt, PanSTARRS Source

Hubble Space Telescope image of Arp 12, also known as NGC 2608. NGC 2608 is a barred spiral galaxy. Its arms are peppered by blue star clusters and red star forming regions and crossed by brown dust lanes. Credit: ESA, NASA, A. Riess et al. Source

ALMA and Hubble image of Arp 220, also known as IC 4553. Dust blocks the center of a galaxy merger in the Hubble visible light view. However, ALMA sees two compact cores in millimeter wavelength light (red). Credit: ALMA(ESO/NAOJ/NRAO), NASA, ESA, and The Hubble Heritage Team Source

Hubble image of Arp 217, also known as NGC 3310. NGC 3310 is a distorted spiral galaxy undergoing a burst of star formation that began about 100 million years ago. A merger with a smaller galaxy may have triggered the starburst. Credit: NASA, ESA, The Hubble Heritage Team Source

Image of Arp 13, also known as NGC 7448, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Detached segments. It has particularly bright spiral arms. Source

JWST image of Arp 298, also known as NGC 7469 and IC 5283. This image is dominated by NGC 7469, a face-on spiral galaxy. Its companion galaxy IC 5283 is partly visible in the lower left corner. Credit: ESA, NASA, CSA, L. Armus, A. S. Evans Source

Image of Arp 85, also known as the Whirlpool Galaxy or M51, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Large, high surface brightness companions. Source

Hubble image of Arp 238, also known as UGC 8335. Gravitational interactions between these two spiral galaxies created a bridge of material and two curved tails of gas and stars. These tails are full of clusters of young, hot, blue, stars. Credit: NASA, ESA, STScI Source

Hubble image of Arp 273, also known as UGC 1810 and UGC 1813. UGC 1810, the larger galaxy in this interacting pair, is distorted into a rose-like shape by the gravity of its companion galaxy, the nearly edge-on UGC 1813. Credit: NASA, ESA, STScI, Hubble Heritage Team Source

Hubble image of Arp 202, also known as NGC 2719 and NGC 2719A. This edge-on disk galaxy and smaller irregularly shaped galaxy had a recent interaction which likely severely perturbed both galaxies. Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons Source

Kitt Peak image of Arp 78, also known as NGC 772. Interactions with its companion galaxy NGC 770, the small elliptical galaxy in the center near the top of the frame, left NGC 772's bottom arm elongated and asymmetrical. Credit: KPNO, NOIRLab, NSF, AURA, A. Block Source

Image of Arp 285, also known as NGC 2854 and NGC 2856, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Double and multiple galaxies - Infall and attraction. This pair had a past interaction. Source

Image of Arp 22, also known as NGC 4027, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - One-armed. It is interacting with a smaller companion galaxy, NGC 4027A, below. Source

Image of Arp 84, also known as NGC 5394 and NGC 5395, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Large, high surface brightness companions. Source

Image of Arp 142, also known as NGC 2936, NGC 2937, and UGC 5130, or the Penguin and the Egg, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Elliptical galaxies - Emanating material. Source

Hubble image of Arp 195, also known as UGC 4653. The Establishing HST's Low Redshift Archive of Interacting Systems snapshot program filled in Hubble schedule gaps with short observations, like this one of three interacting galaxies. Credit: ESA, NASA, J. Dalcanton Source

Image of Arp 287, also known as NGC 2735 and NGC 2735A, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Double and multiple galaxies - Wind effects. Source

Spitzer image of Arp 16, also known as M66. The blue core and bar has a concentration of blue older stars, and the pink bar ends and spiral arms show dust heated by actively forming stars. Credit: NASA/JPL-Caltech/R. Kennicutt (University of Arizona) and the SINGS Team Source

JWST NIRCam and MIRI image of Arp 107, also known as UGC 5984. In the near-infrared, older stars and a bridge of gas and stars between the galaxies appear in white. In the mid-infrared, star-forming regions are in orange and red. Credit: NASA, ESA, CSA, STScI Source

Gemini North image of Arp 78, also known as NGC 772. Interactions with its companion galaxy NGC 770 (out of frame) left NGC 772's bottom arm elongated and asymmetrical. Credit: International Gemini Observatory, NOIRLab, NSF, AURA Source

Legacy Surveys image of Arp 11, also known as UGC 717. UGC 717 is the large spiral galaxy in the lower right. The large spiral in the upper left is UGC 719. Credit: Legacy Surveys, D. Lang, NERSC, Meli thev, Wikimedia Commons Source

Hubble image of Arp 220, also known as IC 4553. Arp 220 is the aftermath of a collision between two spiral galaxies. The collision set off a burst of star formation, creating star clusters seen as bluish-white bright knots in this image. Credit: NASA, ESA, STScI, A. Evans Source

Hubble and Pan-STARRS image of Arp 300, also known as UGC 05028 and UGC 05029. In this image of an interacting galaxy pair, the luminosity comes from Hubble ACS/WFC observations, and color comes from Pan-STARRS. Credit: NASA, ESA, STScI, J. Dalcanton, Judy Schmidt, PanSTARRS Source

Sloan Digital Sky Survey image of Arp 1, also known as NGC 2857. NGC 2857 is a spiral galaxy in the constellation Ursa Major. Credit: SDSS Source

Composite image of Arp 26, also known as M101 or the Pinwheel Galaxy. X-rays from NuSTAR (green) show a supernova, on a visible light (KPNO, yellow and red) and far-UV (GALEX, blue) image of M101. Credit: NASA, JPL-Caltech, NOIRLab, NSF, AURA, B. Grefenstette, R. Hurt Source

Hubble Space Telescope image of Arp 4. This image contains two galaxies, a larger irregular galaxy, Arp 4, and a small spiral galaxy PGC 6629. Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons Source

Image of Arp 6, also known as NGC 2537 or the Bear’s Paw Galaxy, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Low surface brightness. Source

JWST image of Arp 16, also known as M66. This image was taken as part of the PHANGS program, to learn how the small details of how stars form influence the large structures of galaxies. Credit: NASA, ESA, CSA, STScI, J. Lee (STScI), T. Williams (Oxford), PHANGS Team Source

Hubble image of Arp 256. A recent close interaction between these two galaxies distored the shapes of thier disks and triggered a burst of star formation, seen in the blue clusters of hot, young stars. Credit: ESA, NASA Source

ALMA image of Arp 16, also known as M66. This image of M66 shows the location of cold clouds of molecular gas. It’s in these cold, dusty clouds that new stars form. Credit: ESO, ALMA (ESO/NAOJ/NRAO), PHANGS Source

Hubble image of Arp 22, also known as NGC 4028. NGC 4027 is a barred spiral galaxy with a single spiral arm. It is interacting with a smaller companion galaxy, NGC 4027A, just out of frame. Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons Source

Image of Arp 81, also known as NGC 6621 and NGC 6622, from Halton Arp's Atlas of Peculiar Galaxies (1966). In the original catalog it was in the category: Spiral galaxies - Large, high surface brightness companions. Source

NuStar image of Arp 299, also known as NGC 3690. X-ray light from NuSTAR highlights an active supermassive black hole in one of the galaxies in the pair Arp 299. The other galaxy lacks an active black hole and is not seen in the image. Credit: NASA, JPL-Caltech, GSFC Source

Isaac Newton Telescope and Blackbird Observatory image of Arp 189, also known as NGC 4651 or the Umbrella Galaxy. The parasol-shaped feature to the right is debris from the remains of a tiny galaxy that was ripped apart by the large spiral galaxy. Credit: R. Jay GaBany Source

Hubble image of Arp 287, also known as NGC 2735 and NGC 2735A. NGC 2735 is the large spiral in the center. It is interacting with the smaller NGC 2735A. Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons Source