This article documents the most distant

astronomical objects An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...

discovered and verified so far, and the time periods in which they were so classified. For comparisons with the light travel distance of the astronomical objects listed below, the

age of the universe In physical cosmology, the age of the universe is the cosmological time, time elapsed since the Big Bang: 13.79 billion years. Astronomers have two different approaches to determine the age of the universe. One is based on a particle physics ...

since the

Big Bang The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models based on the Big Bang concept explain a broad range of phenomena, including th ...

is currently estimated as 13.787 ± 0.020 Gyr. Distances to remote objects, other than those in nearby galaxies, are nearly always inferred by measuring the

cosmological redshift Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faster ...

of their light. By their nature, very distant objects tend to be very faint, and these distance determinations are difficult and subject to errors. An important distinction is whether the distance is determined via

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

or using a photometric redshift technique. The former is generally both more precise and also more reliable, in the sense that photometric redshifts are more prone to being wrong due to confusion with lower redshift sources that may have unusual spectra. For that reason, a spectroscopic redshift is conventionally regarded as being necessary for an object's distance to be considered definitely known, whereas photometrically determined redshifts identify "candidate" very distant sources. Here, this distinction is indicated by a "p" subscript for photometric redshifts. The proper distance provides a measurement of how far a galaxy is at a fixed moment in time. At the present time the proper distance equals the

comoving distance In standard cosmology, comoving distance and proper distance (or physical distance) are two closely related distance measures used by cosmologists to define distances between objects. ''Comoving distance'' factors out the expansion of the univ ...

since the cosmological scale factor has value one:

a(t_0) = 1

. The proper distance represents the distance obtained as if one were able to freeze the flow of time (set

dt = 0

in the FLRW metric) and walk all the way to a galaxy while using a meter stick. For practical reasons, the proper distance is calculated as the distance traveled by light (set

ds = 0

in the FLRW metric) from the time of emission by a galaxy to the time an observer (on Earth) receives the light signal. It differs from the "light travel distance" since the proper distance takes into account the expansion of the universe, i.e. the space expands as the light travels through it, resulting in numerical values which locate the most distant galaxies beyond the

Hubble sphere In cosmology, a Hubble volume (named for the astronomer Edwin Hubble) or Hubble sphere, subluminal sphere, causal sphere and sphere of causality is a spherical region of the observable universe surrounding an observer beyond which objects reced ...

and therefore with recession velocities greater than the speed of light ''c''.

Most distant spectroscopically-confirmed objects

Candidate most distant objects

Since the beginning of the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. As the largest telescope in space, it is equipped with high-resolution and high-sensitivity instruments, allowing it to view objects too old, Lis ...

's (JWST) science operations in June 2022, numerous distant galaxies far beyond what could be seen by the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

(z = 11) have been discovered thanks to the JWST's capability of seeing far into the

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

. Previously in 2012, there were about 50 possible objects z = 8 or farther, and another 100 candidates at z = 7, based on photometric redshift estimates released by the Hubble eXtreme Deep Field (XDF) project from observations made between mid-2002 and December 2012. Some objects included here have been observed spectroscopically, but had only one emission line tentatively detected, and are therefore still considered candidates by researchers.

List of most distant objects by type

Timeline of most distant astronomical object recordholders

Objects in this list were found to be the most distant object at the time of determination of their distance. This is frequently not the same as the date of their discovery. Distances to astronomical objects may be determined through

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, use of standard references such as

cepheid variable A Cepheid variable () is a type of variable star that pulsates radially, varying in both diameter and temperature. It changes in brightness, with a well-defined stable period (typically 1–100 days) and amplitude. Cepheids are important cosmi ...

s or

Type Ia supernova A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...

s, or

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

measurement. Spectroscopic redshift measurement is preferred, while photometric redshift measurement is also used to identify candidate high redshift sources. The symbol ''z'' represents redshift.

List of objects by year of discovery that turned out to be most distant

This list contains a list of most distant objects by year of discovery of the object, not the determination of its distance. Objects may have been discovered without distance determination, and were found subsequently to be the most distant known at that time. However, object must have been named or described. An object like OJ 287 is ignored even though it was detected as early as 1891 using photographic plates, but ignored until the advent of radiotelescopes.

References