NASA's Hubble Space Telescope captures dwarf irregular galaxy located 23 million light-years away

The telescope operational for over 35 years has been looking at the movement of cosmic matter.

BY PRANJAL NATH

PUBLISHED MAY 28, 2026

HST captures the dwarf irregular galaxy ESO 490-017. [Cover Image Source: NASA | ESA | R. Tully (University of Hawaii) | Image Processing: G. Kober (NASA/Catholic University of America)]

According to NASA, the Hubble Space Telescope has photographed a dwarf irregular galaxy designated the identifier ESO 490-017. It was captured as Hubble was engaged in understanding how galaxies and clusters of galaxies move from one part of the universe to another as part of the “cosmic flow." The reason this galaxy is being characterized as a dwarf is that it measures only 12,000 light-years across. To put its size into perspective, the Milky Way galaxy is about 100,000 light-years in diameter.

Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear) (Image Source: ESA/Hubble and NASA | Judy Schmidt) — Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear) (Representative Image Source: ESA | NASA | Judy Schmidt)

The irregularity in the shape of ESO 490-017 appears in contrast to the usual spiral structures of distant galaxies visible in the backdrop of the same picture taken by the Hubble. The galaxy appears to be nothing more than a collection of faint stars, which means it has a low surface brightness.

A simulation of the formation of dark matter structures from the early universe until today (Image Source: Ralf Kaehler/SLAC National Accelerator Laboratory, American Museum of Natural History)

As for the aforementioned cosmic flow process being studied by Hubble, the tracking of the movement of matter towards dense parts of the universe will aid in the detection of dark matter. Due to this movement, voids in space are being created, as these places are left with no structures with mass. While data about this movement was being collected, ESO 490-017 was observed in the constellation Canis Major. It is located at a distance of around 23 million light-years away from us, which was measured with the aid of 'standard candles.' These are reference points such as low-mass red giant stars, which help in the measurement of large distances through the comparison of their absolute brightness and their apparent brightness.

Canis Major Dwarf Galaxy's illustration. (Representative Image Source: R. Ibata (Strasbourg Observatory, ULP) et al. | 2MASS | NASA)

This dwarf galaxy (ESO 490-017) should not be confused with the Canis Major dwarf galaxy, which lies much closer to us at roughly 25,000 light-years and is being ripped apart by our own galaxy. This is causing it to leave a long filament of stars, gas, and dust in its wake as it orbits our host galaxy. It lies behind a thick veil of dust in the plane of the Milky Way, which is why it wasn't discovered until 2003.

NASA's James Webb Space Telescope recently imaged an extremely large and symmetric protostellar jet at the outskirts of our Milky Way galaxy in the forming cluster Sh2-284 (Cover Image Source: NASA, ESA, CSA, STScI | Yu Cheng) — Images from NASA's James Webb Space Telescope feature six diffraction spikes as opposed to four seen in HST images (Representative Image Source: NASA, ESA, CSA, STScI | Yu Cheng)

The image also features bright stars in the foreground with signature diffraction spikes that appear as bright lines emerging from a light source. NASA has explained that this happens due to the four struts on the Hubble that support its secondary mirror. Hubble is expected to operate well into the 2030s, despite initially only being designed to have a lifespan of 15 years since being launched in 1990. Its foundational work is being built upon by other space telescopes, such as the James Webb Space Telescope, and will be carried forward by the Nancy Grace Roman telescope, which launches later this year.

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