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G

Galactic disk

(Last edited: Thursday, 31 August 2023, 4:11 PM)


Short Definition:

A galactic disc is a component of disc galaxies. An example are spiral galaxies and the Milky Way. The set-up of Galactic discs are a stellar component (these encompass the majority of the galaxy's stars) as well as a gaseous component (simply largely composed of cold gas and dust).

Detailed Definition:

The stellar disc of our Galaxy is divided into two components because the vertical density profile determined from star counts can be explained by a superposition of two exponentials, but not by a single exponential. (Gilmore & Reid, 1983). Further study found a thick-disc component with high-velocity dispersion, significant enrichment, and ancient age. Many writers believe that the thick disc was a relic of a turbulent period in Galactic history when the thick disc developed from accreted satellites or a thin disc heated the substance at high temperatures by one or more merger events (for a discussion, see Reddy Lambert, and Allende Prieto 2006).

This structure was first observed in external edge-on galaxies and later proposed as a distinct part of the Milky Way in a 1983 article by Gilmore and Reid. It is separate from both the thin disk and the halo. The thick disk is a structural component of approximately two-thirds of all disk galaxies, including the Milky Way. It was initially detected in external edge-on galaxies. Soon later, in the 1983 article by Gilmore and Reid, it was proposed as a galactic structure in the Milky Way, distinct from the thin disk and the halo.

Etymology

The term galaxy was derived from the Greek word galaxas (kklos) (o), which means "milky (circle)," and was called by its appearance in the sky as a milky ring of light.

Sample Sentence(s):

1.     It would take two billion years for the changes caused by a Galactic Battle to be realized.

2.     It glows on the galactic scale.

3.     The galactic disk is the Milky Way's disk component.

Translations of Terms/Concepts into Partner Languages

Polish: dysk galaktyczny

French: disque galactique

German: galaktische Scheibe

Italian: disco galattico

Swedish: galaktisk skiva



Galaxy

(Last edited: Friday, 28 April 2023, 6:09 PM)


Image/Video/Audio Source:

Short Definition:
A galaxy is a system composed of a star and an interstellar matter that is held together by the gravity force.

Detailed Definition:
A galaxy is a vast collection of stars, their solar systems, gas, and dust. In the centre of the galaxy a massive black hole is placed. Galaxies have different shapes from one another, with variations deriving from how the systems were created and later evolved. A few galaxies resemble our own in spiral shape. They possess curved arms that give it a pinwheel-like appearance. Others have smooth surfaces and oval forms. Scientists refer to them as elliptical galaxies. There are galaxies that are neither spirals nor ovals, either. They mimic blobs and have amorphous forms. Each of these galaxies emits light that we can see from its stars. In the future some galaxies will collide like NGC 4567 and NGC 4568 (commonly referred to as the Butterfly galaxies) started to do so and some will drift apart that the light from its stars will not reach the Earth.

Etymology:
Old French from medieval Latin galaxia, from Greek galaxias (kuklos) ‘milky (vault)’, from gala, galakt-‘milk’.

Sample Sentence(s):
When the sky is dark, centre of our galaxy is perfectly visible.

Translations:
French:
Une galaxie

German:
die Galaxie

Polish:
Galaktyka

Swedish:
En galax

Spanish:
Una galaxia

Links to Videos/Articles:
https://spaceplace.nasa.gov/galaxy/en/
https://en.wikipedia.org/wiki/Galaxy
https://www.britannica.com/science/galaxy
https://edition.cnn.com/2022/08/10/world/colliding-galaxies-gemini-north-image-scn/index.html



Galaxy cluster

(Last edited: Thursday, 31 August 2023, 4:12 PM)


Short Definition
Galaxy cluster is astronomical structure that consist of dark matter, hot plasma and galaxies. They are the biggest bound by gravity formations that we know of.


Detailed Definition

Galaxy clusters are the biggest structures bound by gravity. They consist in 85% of dark matter that is connecting the whole structure together. We can detect dark matter only by observing how its gravitation affects objects around it and what influence it has on light passing near it. The amount of gravity produced in clusters by dark matter is a cause for effect called “gravitational lensing”. That effect bends the light magnifying it and making the cluster into a big natural telescope. Without it, we wouldn’t be able to observe some of the smaller, further galaxies.

Most of the visible matter in galaxy clusters is in form of hot plasma called the intracluster medium (ICM). Due to the high gravitational potential energy of material the shock sends gas into really high temperatures that can raise up to 10s of millions grad Celsius. That temperature later causes the emission of X-Rays.

The smallest part of galaxy clusters are galaxies, they are around 2% of a total mass of the structure. Yet the biggest known to us galaxies are formed in clusters.


Etymology

Galaxy (Noun.), originated from Ancient Greek word galaxías, that means “Milky Way”. At first used only to describe Milky Way Galaxy, later on it changed its meaning to more general.

Cluster (Noun.), derived from Proto-Germanic *klas-, *klus-, meaning “to clump, lump together”.

Sample Sentence(s)

Galaxy clusters can consist of thousands of galaxies.

Translations of Terms/Concepts into Partner Languages

French: amas de galaxies

German: Galaxienhaufen

Italian: mmasso di galassie

Polish: gromada galaktyk

Swedish: galaxhop


Links to Videos/Articles:

  1. Max Planck Institute for Extraterrestrial Physics (n.d.), Clusters and Group of Galaxies, Retrieved from https://www.mpe.mpg.de/2040034/clusters_and_groups_of_galaxies
  2. Center for Astrophysics Harvard & Smithsonian (n.d.), Galaxy Clusters, Retrieved from https://www.cfa.harvard.edu/research/topic/galaxy-clusters
  3. Online Etymology Dictionary (n.d.), galaxy (n.), Retrieved from https://www.etymonline.com/word/galaxy#etymonline_v_1225
  4. Online Etymology Dictionary (n.d.), cluster (n.), Retrieved from https://www.etymonline.com/word/cluster#etymonline_v_13860
  5. European Space Agency (2007, Juli), The Bullet Cluster, Retrieved from https://www.esa.int/ESA_Multimedia/Images/2007/07/The_Bullet_Cluster2#.ZFmq1Dq136A.link  


Galaxy Evolution

(Last edited: Friday, 28 April 2023, 6:09 PM)

Picture: Model of Evolution of Galaxy

Image/Video/Audio Source:

https://upload.wikimedia.org/wikipedia/commons/a/a3/Evolution_in_slow_motion.jpg

Short Definition:

Galaxy evolution or evolution of galaxy is a term that we have used for understanding the formation process and changes of galaxies since the beginning that made up the known universe. The term galaxy evolution also represents the models we form about the universe filled by the observed photons and the expansion since the big bang. At this point, the sizes, shapes and contents of all galaxies give us an idea about the formation and evolution of the universe.

Detailed Definition:

Galaxy evolution is a term used to understand the structure of the universe and the ongoing formation processes by comparing the morphology, brightness and content of galaxies with each other. The term galaxy evolution here studies galaxies in four main groups. These are Elliptical Galaxies, Lenticular Galaxies, Spiral Galaxies, and Irregular galaxies. The evolution process of galaxies in these four groups is examined under three main headings. These are Passive evolution (The state where the galaxy does not interact with any other galaxy [interactions or mergers] and thus does not produce star formations.), Interactions and Mergers (The state in which galaxies are affected by interacting with other galaxies), Secular Evolution (Situation in which processes by internal changes of galaxies affect their colour, luminosity and shape.)

Etymology:

From Latin ‘Galaxias’ and From Latin ‘ēvolūtiōnis’ (Unrolling/Unfolding)

Sample Sentence(s):

Radio telescopes have played a pivotal role in the understanding of galactic evolution.’’

(Galaxy Evolution, Cosmology and Dark Energy. (2018, May 30). Public Website. 

https://www.skatelescope.org/galaxyevolution/)

‘’Understanding how black holes shape their host galaxies is part of the study of galactic structure and evolution.’’

(Galaxy Formation and Evolution | Center for Astrophysics. (n.d.). https://www.cfa.harvard.edu/research/topic/galaxy-formation-and-evolution)

Translations of Terms/Concepts into Partner Languages:

French:

Évolution de la galaxie

German:

Galaxienentwicklung

Polish:

Ewolucja galaktyki

Swedish:

Utveckling av galaxer

Turkish:

Galaksi Evrimi

Links to Videos/Articles:

https://www.britannica.com/science/galaxy/Evolution-of-galaxies-and-quasars

https://www.jwst.nasa.gov/content/science/galaxies.html

https://www.skatelescope.org/galaxyevolution/

https://www.cfa.harvard.edu/research/topic/galaxy-formation-and-evolution

https://sites.astro.caltech.edu/~george/ay20/eaa-galevol.pdf

https://astronomy.swin.edu.au/cosmos/E/evolution+of+galaxies

https://www.youtube.com/watch?v=Rdd9KAUcvgQ&ab_channel=TakayukiSaitoh

https://www.youtube.com/watch?v=_WtvU4Xn2UE&ab_channel=CaltechAstro



Galaxy Merger

(Last edited: Saturday, 30 September 2023, 8:22 PM)
Source: https://www.eso.org/public/images/1016-galaxy_formation_merger/

Source: https://www.eso.org/public/images/1016-galaxy_formation_merger/

Short Definition:

A galaxy merger is the phenomenon of two or more galaxies colliding with each other, resulting in the formation of a new, enlarged galaxy.

Detailed Definition:

A galaxy merger occurs when two or more galaxies collide with each other, leading to the creation of a larger galaxy. Galaxy mergers are the most violent type of galaxy interaction. When a collision of several galaxies occurs, the stars and dark matter in each of them become affected, which has influence on both the orbits of the stars and the shape of the newly formed galaxy. 

During a merger, an increase in star formation can be observed, as the friction interaction of gas and dust contributes to the raise of energy in the resulting system. Galaxy mergers provide astronomers with the merger rate, which is a fundamental measurement of galaxy evolution and sheds some light on how galaxies have increased in size over time.

Etymology:

merge - Latin mergere"to dip, dip in, immerse, plunge"

galaxy - Late Latin galaxias - Greek galaxías

Sample Sentence(s):

Galaxy mergers can be simulated in computers, to learn more about galaxy formation.

Translations of Terms/Concepts into Partner Languages

French: Fusion de galaxies

German: Galaxienfusion

Polish: Fuzja galaktyk, połączenie się galaktyk

Swedish: Galaxsammanslagning


Links to Videos/Articles:

https://www.eso.org/public/images/1016-galaxy_formation_merger/

https://www.thoughtco.com/interacting-galaxies-have-interesting-results-3072045

https://www.youtube.com/watch?v=4disyKG7XtU



Gamma ray

(Last edited: Saturday, 30 September 2023, 8:30 PM)
Illustration of an emission of a gamma ray ( γ ) from an atomic nucleus Source: https://en.wikipedia.org/wiki/Gamma_ray#/media/File:Gamma_Decay.svg

Illustration of an emission of a gamma ray ( γ ) from an atomic nucleus Source: https://en.wikipedia.org/wiki/Gamma_ray#/media/File:Gamma_Decay.svg

Short Definition:

Gamma rays are very high frequency electromagnetic radiation emitted as an outcome of radioactivity. Due to high frequency, gamma rays have very high energy. Natural sources of gamma emission originating on Earth are mainly an effect of radioactive decay and secondary radiation from atmospheric interactions among cosmic ray particles.

Detailed Definition:

A gamma ray, also known as gamma radiation, is a penetrating form of electromagnetic radiation originating from the radioactive decay of atomic nuclei. Gamma rays from radioactive decay are within the energy range starting at few kiloelectronvolts (keV) to roughly 8 megaelectronvolts (MeV), matching to the usual energy levels in nuclei among reasonably long lifetimes. The energy spectrum of gamma emission can be utilized to recognize the decaying radionuclides with a technique called gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from sources such as the Cygnus X-3 microquasar.

Etymology:

gamma - The third letter of the Greek alphabet (Γ, γ),
radiation - From the past participle stem of Latin radiare (“to gleam, shine, beam”).

Sample Sentence(s):

"Solar flares emit across the entire electromagnetic spectrum, including gamma rays."
"Gamma rays originating from far-distant quasars are used to estimate the extragalactic background light in the universe."

Translations:

French: 

Rayon gamma

German:

Gammastrahlung

Polish:

Promieniowanie gamma, promienie gamma

Swedish:

Gammastrålning

Links to Videos/Articles:




Geosynchronous orbit

(Last edited: Thursday, 31 August 2023, 5:13 PM)
Projection of the path traced by geosynchronous satellites of different inclinations. Source: Wikipedia

Projection of the path traced by geosynchronous satellites of different inclinations. Source: Wikipedia

Short Definition:
Geosynchronous orbit is an orbit with orbital period matching Earth's full rotation time.

Detailed Definition:
Objects in geosynchronous orbit appear to trace out a path on the sky, typically a figure-8 shape every day. The exact path depends on orbit's eccentricity and inclination, but the object can be observed in the same place on the sky, same time every day. This type of orbit is useful for example for Earth observing satellites.

Etymology:
From ancient greek geo (Earth) + synchronous

Sample Sentence(s):
A satellite is placed in geosynchronous orbit above Europe.

Translations:

French:
orbite géosynchrone

German:
geosynchrone Umlaufbahn

Polish:
Orbita geosynchroniczna

Swedish:
geosynkron bana

Links to Videos/Articles:
https://www.space.com/29222-geosynchronous-orbit.html
https://gisgeography.com/geosynchronous-geostationary-orbits/


Gravity

(Last edited: Friday, 26 May 2023, 5:25 PM)

Image/Video/Audio:




Image/Video/Audio Source:



Short Definition:

Gravity is one of the fundamentals of the universe and the force of attraction between every single existing body. It keeps the universe and our solar system, together.


Detailed Definition:

One of the first theories about the existence of gravity was made by Aristotle, a Greek philosopher. He believed that objects tend toward their inner heaviness. Many researches and scientists later, this theory became more developed and finally, in XVII century Isaac Newton (after being hit by the famous apple) described gravity as a force that keeps the planets in their place. This definition evolved into a law and formula (F=G*(M*m)/r^2) which we use today. 

Every object has its gravitational field. The heavier the object, the greater is its force of attraction in this field. An apple has its gravitational field too, however it weighs thousands of times less than a planet. That is why we don't see it every day. The gravitational force of a planet is so big that we need a great speed and precise calculations to be able to fly away from it and not be brought back. It is measured by the acceleration it gives to the falling object. For example, at Earth's surface it is equal to 9,81 m/s and at the Moon's only 1,6 m/s.


Etymology:

from Old French, or from Latin gravitas ‘weight, seriousness’



Sample Sentence(s):

Every object with mass has gravity. Gravity creates stars and planets by pulling together the material from which they are made.


Translations of Terms/Concepts into Partner Languages [Multiple fields for entering the translation of the term in each partner language, additional languages can potentially be added, e.g. Russian, Chinese, Portuguese]

French: 

la gravité


German:

die Schwere


Polish:

grawitacja


Swedish:

allvar


Links to Videos/Articles:



Gravity Assist

(Last edited: Monday, 13 March 2023, 3:55 PM)


Source: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2143https://commons.wikimedia.org/w/index.php?curid=18049439



Short Definition:

Gravity assistance describes the intentional use of the gravitational attraction of a celestial body, in order to modify the trajectory of a space vehicle. This maneuver allows the spacecraft to save rocket fuel.


Detailed Definition:

Etymology:

1. Gravity (Noun.), originating from the Latin word gravitatem, with the meaning of “weight, heaviness, pressure

2. Assist (Verb.), originating from Latin word assistere, which means “standing by, help”

Sample Sentence(s):

“The global minimum velocity increments of direct transfer trajectory and gravity-assist trajectories are obtained for each candidate target.”


Translations:
  • French: Assistance gravitationnelle
  • German: Schwerkraftumlenkung
  • Polish: Asysta grawitacyjna
  • Swedish: Gravitationsslunga

Links to Videos/Articles:

  1. "Section 1: Environment, Chapter 4: Trajectories". Basics of Space Flight. NASA. 
  2. "Gravity assist". The Planetary Society. 


Great Red Spot

(Last edited: Thursday, 31 August 2023, 5:14 PM)
Sources: Stewart, P. (2018, June 8). Jupiter. flickr. https://www.flickr.com/photos/106648653@N05/42658035711

Sources: Stewart, P. (2018, June 8). Jupiter. flickr. https://www.flickr.com/photos/106648653@N05/42658035711


Definition:
A persistent large anticyclonic storm in the atmosphere of Jupiter, 22° south from its equator, which has been continuously observed since the 19th century.

As of 2021, the Great Red Spot is reported to be about 10,000 miles across and 300 miles deep into the atmosphere of Jupiter. However, according to NASA observations, it is shrinking and becoming taller, and it is not yet clear whether the Great Red Spot will stabilize or disappear completely.


Translation:
  • French: la Grande Tache rouge
  • German: der Große Rote Fleck
  • Polish: Wielka Czerwona Plama
  • RussianБольшое Красное Пятно 
  • Swedish: Stora röda fläcken

Links to Videos/Articles:
https://www.youtube.com/watch?v=JDi4IdtvDVE