Glossary term: Cosmology

Description: Cosmology is derived from the Greek words kosmos (harmony or order), and logos (thought or reason). Cosmology as a discipline has its roots in philosophy and religion; various cultures around the world have their own cosmologies that aim to interpret and make sense of the Universe. Over the years cosmology has evolved to be a precision observational science. This has been made possible through the development of advanced ground-based and space-based observatories, together with pioneering theoretical work and computer simulations. Cosmology as a scientific endeavor aims to understand the evolutionary history, formation, structure, and future evolution of the Universe as a whole on the largest scales, by understanding the fundamental physical mechanisms operating within the Universe.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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The Hubble Ultra Deep Field showing around 10,000 galaxies of various ages, sizes, shapes and colours.

Hubble Ultra Deep Field

Caption: This awe-inspiring image referred to as the Hubble Ultra-Deep Field (HUDF), was obtained using the Hubble Space Telescope (HST), by combining 800 exposures from 400 orbits of the HST, which equates to 11.3 days of total exposure time. The image shows nearly 10,000 galaxies and was taken in the direction of a patch of sky with the least amount of stars from the Milky Way galaxy in the field of view. The region of sky that the HST observed corresponds to 1/10 the angular size of the Full Moon, which is roughly equal to approximately a 1 millimeter-sized object placed 1 meter away. Every object in the image, except for the bright points with the crosshairs, are galaxies. As a consequence of the speed of light being a constant in a vacuum, the more distant an object, the further back in time we are observing. Therefore, the light from some of the galaxies in the HUDF image is from when the Universe as only a few hundred million years old. The HUDF image takes us through on a journey through space, and also in time.
Credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team credit link

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons

This Cosmic Microwave Background Radiation map is an oval with many patches of different colors as well as finer granulation

Cosmic Microwave Background Radiation

Caption: This image is a representation of the Cosmic Microwave Background (CMB) Radiation created using data from the Planck satellite. The CMB is the glow left over from when the Universe was approximately 380,000 years old. The early Universe was hot and dense, so the photons from that era were high energy. Due to the expansion of the Universe over 13.8 billion years photons of ""light"" from the early Universe have been stretched to longer wavelengths and are detectable in millimetre wavelengths (microwave region of the electromagnetic spectrum). The ""mottled"" pattern in the image is referred to as anisotropies, and it represents very small temperature fluctuations. These fluctuations correspond to regions of slightly different densities, and are essentially the seeds for larger structure in the Universe e.g.: galaxies, galaxy clusters, and the very first stars. The data from the CMB allows various characteristics of the Universe to be derived, for example, composition, shape, age, and allows for certain predictions to be made about the future evolution of the Universe. The shape of the image is the result of a mapping projection, where the entire sky is mapped onto a single flat oval shape called Molleweide projection. The center of the Milky Way galaxy is located at the centre of the image.
Credit: ESA/Planck Collaboration credit link

License: CC-BY-SA-4.0 Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) icons