Webb's First Deep Field is the first operational image taken by the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

(JWST). The deep-field photograph, which covers a tiny area of sky visible from the Southern Hemisphere, is centered on SMACS 0723, a

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-l ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Volans Volans is a constellation in the southern sky. It represents a flying fish; its name is a shortened form of its original name, Piscis Volans. Volans was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirks ...

. Thousands of

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

are visible in the image, some as old as 13 billion years. The image is the highest-resolution image of the

early universe The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, wit ...

ever taken. Captured by the telescope's

Near-Infrared Camera NIRCam (Near-InfraRed Camera) is an instrument aboard the James Webb Space Telescope. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other wor ...

(NIRCam), the image was revealed to the public by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

on 11 July 2022.

Background

The

is a

space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launched ...

operated by

and designed primarily to conduct

infrared astronomy Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in betwee ...

. Launched in December 2021, the spacecraft has been in a

halo orbit A halo orbit is a periodic, three-dimensional orbit near one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it ca ...

around the second Sun–Earth

Lagrange point In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...

(L₂), about from Earth, since January 2022. At L₂, the

gravitational pull In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stron ...

of the Sun combines with the gravitational pull of the Earth to produce an orbital period that matches Earth's, and the Earth and Sun remain co-aligned (as seen from that point) as the Earth and the spacecraft orbit the Sun together. Webb's First Deep Field was taken by the telescope's

(NIRCam) and is a composite produced from images at different

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...

s, totalling 12.5 hours of exposure time. SMACS 0723 is a galaxy cluster visible from Earth's Southern Hemisphere, and has often been examined by Hubble and other telescopes in search of the deep past.

Scientific results

The image shows the galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago, covering an area of sky with an

angular size The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

approximately equal to a grain of sand held at arm's length. Many of the objects in the image have undergone notable

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 simultaneous increase in f ...

due to the

expansion of space The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not exp ...

over the extreme distance traveled by the light radiating from them. The redshifts of nearly 200 of these objects have been measured to date, with the highest redshift measured at 8.498. The combined mass of the galaxy cluster acts as a

gravitational lens A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...

, magnifying and distorting the images of much more distant galaxies behind it. Webb's NIRCam brought the distant galaxies into sharp focus, revealing tiny, faint structures that had never been seen before, including

star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clust ...

s and diffuse features.

Diffraction spikes in the photo

$JWST_diffraction_spikes$ The six bright and two fainter spikes around the point sources of light in the photo are an artifact created by the physical limitations of the telescope. The six bright spikes are a result of

diffraction Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

from the mirror's edges. The mirror is composed of 18 individual units, each having the shape of a

regular hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

. The hexagonal rim of the units that make up the telescope's large mirror give rise to the six spikes. Telescopes with circular mirrors/lenses don't have such spikes (in lieu of spikes, diffraction from circular rims creates a pattern of concentric rings called

Airy disc In optics, the Airy disk (or Airy disc) and Airy pattern are descriptions of the best- focused spot of light that a perfect lens with a circular aperture can make, limited by the diffraction of light. The Airy disk is of importance in physics, ...

s). The two additional spikes are a result of diffraction from the struts holding the telescope's secondary mirror in front of the main mirror. As shown in the figure on the right, diffraction from the three struts creates six spikes, but four of these are designed to co-align with the spikes created from the diffraction caused by the rim. This leaves the two faint horizontal spikes visible in the photo.

Significance

Deepest image of the Universe

On July 12, 2022 JWST delivered the deepest sharp infrared image of the universe to date. Webb's First Deep Field is the first full

false-color False color (or pseudo color) refers to a group of color rendering methods used to display images in color which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an image that depicts ...

image from the JWST, and the highest-resolution infrared view of the universe yet captured. The image reveals thousands of galaxies in a tiny sliver of the universe, with Webb's sharp near-infrared view bringing out faint structures in extremely distant galaxies, offering the most detailed view of the early universe to date. Thousands of galaxies, which include the faintest objects ever observed in the infrared, have appeared in Webb's view for the first time. It was first revealed to the public during an event on 11 July 2022 by U.S. President Joe Biden.

Comparison with the Hubble Space Telescope

The following images are a comparison with the image taken by the

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

and the image taken by Webb of the same galaxy cluster.

References

{{Sky, 07, 23, 19.5, -, 73, 27, 15.6 James Webb Space Telescope Physical cosmology Sky regions Astronomy image articles 2022 in spaceflight 2020s photographs Color photographs 2022 works