Credit: ESA/Hubble & NASA
The distances to objects in the Universe can differ enormously. The nearest star to us — Proxima Centauri — lies some 4.2 light-years from us, while some incredibly distant galaxies are so far away — 13 billion light-years or more — that they are only visible to us as a result of cosmic tricks of magnification.
The subject of this image, a galaxy called ESO
376-16, sits nearly 23 million light-years from Earth — not that great a
distance on a cosmic scale. However, given the galaxy’s relative
proximity to us, we know surprisingly little about it. Astronomers are
still debating about many of the properties of ESO 376-16, including its
morphology. Galaxies are divided into types based on their visual appearance and characteristics; spiral galaxies,
like the Milky Way, are flattened discs with curved arms sweeping out
from a central nucleus, while irregular galaxies lack a distinct
structure and look far more chaotic. On the basis of its rather
ill-defined morphology, ESO 376-16 is thought to be either a late-type
spiral or a dwarf irregular galaxy.
Despite its mystique, observations of ESO 376-16 have been useful in several studies, including one made with the NASA/ESA Hubble Space Telescope
that aimed to create a 3D map of galaxies lying in the vicinity of
Earth. Researchers used Hubble to gauge the distance to galaxies
including ESO 376-16 by measuring the luminosities of especially bright red-giant-branch
stars sitting within the galaxies. They then used their data to
generate and calibrate 3D maps of the distribution of galaxies
throughout the nearby cosmos.
Source: ESA/Hubble/Potw
