Cosmology

Massive galaxy cluster MACS J0717.5+3745, as seen by the Hubble Space Telescope. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)

What are the biggest objects in the Universe?

Chris Lintott during filming for The Sky at Night. Credit: BBC/The Sky at Night

Interview Chris Lintott talks citizen science

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The 12 books of Christmas 2018

The picture shows Abell 2218, a rich galaxy cluster composed of thousands of individual galaxies. It sits about 2.1 billion light-years from the Earth (redshift 0.17) in the northern constellation of Draco. When used by astronomers as a powerful gravitational lens to magnify distant galaxies, the cluster allows them to peer far into the Universe. However, it not only magnifies the images of hidden galaxies, but also distorts them into long, thin arcs. Several arcs in the image can be studied in detail thanks to Hubble's sharp vision. Multiple distorted images of the same galaxies can be identified by comparing the shape of the galaxies and their colour. In addition to the giant arcs, many smaller arclets have been identified.

A guide to gravitational lensing

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CERN tests show early Universe was fluid

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Early Universe emptier than expected

An artist’s impression of a collision between our Galaxy and a smaller dwarf galaxy 10 billion years ago: an event that may be responsible for the Milky Way’s central bulge. Image Credit: V. Belokurov (Cambridge, UK); based on image by ESO/Juan Carlos Muñoz.

Early Milky Way collided with small galaxy

A colour image of the cluster showing the three spectra of the gravitationally lensed images. The graphs show peaks at the same wavelength, indicating they all belong to the same source. Credit: BRADAC/HST/W. M. KECK OBSERVATORY

Faintest early-Universe galaxy confirmed

An illustration of a binary star system within a globular cluster. Credit: Mark A. Garlick/University of Warwick

Globular clusters younger than thought?

An artist’s impression of the most-distant supermassive black hole ever discovered, part of a quasar from just 690 million years after the Big Bang. Credit: Robin Dienel

Found: most distant black hole ever observed

A representation of the technique used to probe the small-scale structure of the cosmic web using light from a rare quasar pair. Bottom right shows spectra containing information about the hydrogen gas the light has encountered, as well as the distance of that gas.
Credit: Springel et al. (2005) (cosmic web) / J. Neidel, MPIA

Astronomers observe ripples in the cosmic web

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Faintest ‘normal’ early galaxy ever discovered

A view of galaxy cluster Abell 2744 by the Hubble Space Telescope. Beyond this cluster, seen inset, is galaxy A2744_YD4. The galaxy is so far away, astronomers could only view it using a technique called gravitational lensing, in which closer, massive galaxies act as a sort of cosmic telescope. Credit: ALMA (ESO/NAOJ/NRAO), NASA, ESA, ESO and D. Coe (STScI)/J. Merten (Heidelberg/Bologna)

Dust-rich early galaxy discovered

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Universe measurement suggests ‘missing’ physics

Among other data, scientists used the galaxies visible in the Great Observatories Origins Deep Survey (GOODS) to recalculate the total number of galaxies in the observable Universe. The image was taken by the NASA/ESA Hubble Space Telescope and covers a portion of the southern field of GOODS. This is a large galaxy census, a deep-sky study by several observatories to trace the formation and evolution of galaxies.

Universe contains ten times more galaxies