Fornax is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern constellations.
Tucana is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a 35-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the "Southern Birds".
The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995.
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. Initially, it was estimated that there may be 2 trillion galaxies in the observable universe. That number was reduced in 2021 to only several hundred billion based on data from New Horizons. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical region centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.
IC 10 is an irregular galaxy in the constellation Cassiopeia. It was discovered by Lewis Swift in 1887 and in 1935 Nicholas Mayall became the first to suggest that the object is extragalactic. Edwin Hubble suspected it might belong to the Local Group of galaxies, but its status remained uncertain for decades. The radial velocity of IC 10 was measured in 1962, and it was found to be approaching the Milky Way at approximately 350 km/s, strengthening the evidence for its membership in the Local Group. Its membership in the group was finally confirmed in 1996 by direct measurements of its distance based on observations of Cepheids; most estimates place the galaxy 2-3 million light years from Earth, with some estimates ranging from 1.5-4.5 million light years. Despite its closeness, the galaxy is rather difficult to study because it lies near the plane of the Milky Way and is therefore heavily obscured by interstellar matter.
The Hubble Ultra-Deep Field (HUDF) is a deep-field image of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies. The original data for the image was collected by the Hubble Space Telescope from September 2003 to January 2004. It includes light from galaxies that existed about 13 billion years ago, some 400 to 800 million years after the Big Bang.
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Astronomers have derived two different measurements of the age of the universe: a measurement based on direct observations of an early state of the universe, which indicate an age of 13.787±0.020 billion years as interpreted with the Lambda-CDM concordance model as of 2021; and a measurement based on the observations of the local, modern universe, which suggest a younger age. The uncertainty of the first kind of measurement has been narrowed down to 20 million years, based on a number of studies that all show similar figures for the age. These studies include researches of the microwave background radiation by the Planck spacecraft, the Wilkinson Microwave Anisotropy Probe and other space probes. Measurements of the cosmic background radiation give the cooling time of the universe since the Big Bang, and measurements of the expansion rate of the universe can be used to calculate its approximate age by extrapolating backwards in time. The range of the estimate is also within the range of the estimate for the oldest observed star in the universe.
The distance modulus is a way of expressing distances that is often used in astronomy. It describes distances on a logarithmic scale based on the astronomical magnitude system.
The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion; the universe does not expand "into" anything and does not require space to exist "outside" it. To any observer in the universe, it appears that all but the nearest galaxies recede at speeds that are proportional to their distance from the observer, on average. While objects cannot move faster than light, this limitation only applies with respect to local reference frames and does not limit the recession rates of cosmologically distant objects.
Abell 370 is a galaxy cluster located nearly 5 billion light-years away from the Earth, in the constellation Cetus. Its core is made up of several hundred galaxies. It was catalogued by George Abell, and is the most distant of the clusters he catalogued.
3C 66A is a blazar located in the constellation Andromeda.
UDFy-38135539 is the Hubble Ultra Deep Field (UDF) identifier for a galaxy which was calculated as of October 2010 to have a light travel time of 13.1 billion years with a present proper distance of around 30 billion light-years.
UDF 2457 is the Hubble Ultra Deep Field (UDF) identifier for a red dwarf star calculated to be about 59,000 light-years from Earth with a very dim apparent magnitude of 25.
HUDF-JD2 is a distant, massive, post-starburst galaxy that was discovered with the Hubble Ultra Deep Field (HUDF) image. It was the most distant galaxy identified in the HUDF, in 2005. It is located at 03h 32m 38.7268s −27° 48′ 39.885″ in the constellation of Fornax.
EGS-zs8-1 is a high-redshift Lyman-break galaxy found at the northern constellation of Boötes. In May 2015, EGS-zs8-1 had the highest spectroscopic redshift of any known galaxy, meaning EGS-zs8-1 was the most distant and the oldest galaxy observed. In July 2015, EGS-zs8-1 was surpassed by EGSY8p7 (EGSY-2008532660).
GN-z11 is a high-redshift galaxy found in the constellation Ursa Major. It is among the farthest known galaxies from Earth ever discovered. The 2015 discovery was published in a 2016 paper headed by Pascal Oesch and Gabriel Brammer. Up until the discovery of JADES-GS-z13-0 in 2022 by the James Webb Space Telescope, GN-z11 was the oldest and most distant known galaxy yet identified in the observable universe, having a spectroscopic redshift of z = 10.957, which corresponds to a proper distance of approximately 32 billion light-years. Data published in 2024 established that the galaxy contains the most distant, and therefore earliest, black hole known in the universe.
NGC 174 is a barred spiral or lenticular galaxy around 159 million light-years away in the constellation Sculptor. It was discovered on 27 September 1834 by astronomer John Herschel.
Bedin I is a dwarf spheroidal galaxy located in the constellation Pavo. It is situated around 28.38 million light-years from Earth, behind the globular cluster NGC 6752. Bedin I is possibly one of the oldest galaxies known, having formed around 10–13 billion years ago, and is one of the most isolated dwarf galaxies known, situated around 2.12 million light-years away from NGC 6744, its nearest neighbor with which it may be physically associated. As such, it has been deemed by astronomers as a "fossil" from the early universe. It was accidentally discovered by Italian astronomer Luigi Bedin, whose team was studying white dwarfs in NGC 6752 using the Hubble Space Telescope in September 2018; the discovery was announced in a paper published in January 2019.
Donatiello I, also known as Mirach's Goblin, is a dwarf spheroidal galaxy in the constellation Andromeda, located between 8.1 and 11.4 million light-years from Earth. It is a possible satellite galaxy of the dwarf lenticular galaxy NGC 404, "Mirach's Ghost", which is situated 60 arcminutes away. It is otherwise one of the most isolated dwarf spheroidal galaxies known, being separated from NGC 404 by around 211,000 light-years. The galaxy is named after its discoverer, amateur astrophotographer Giuseppe Donatiello, who sighted the galaxy in a 2016 review of his archival long exposures from 2010 and 2013. Follow-up observations with the Roque de los Muchachos Observatory led to a scientific paper on its discovery being published in December 2018.
The Hubble Legacy Field is an image of a small region of space in the constellation Fornax, containing an estimated 265,000 galaxies. The original release was composed of Hubble Space Telescope data accumulated over a 16-year period. Looking back approximately 13 billion years it has been used to search for galaxies that existed at that time. The image was taken in a section of the sky with a low density of bright stars in the near-field, allowing much better viewing of dimmer, more distant objects. It builds on the data collected for the Hubble Ultra-Deep Field, the Hubble eXtreme Deep Field and the Great Observatories Origins Deep Survey.
