* Number of superclusters in the visible universe = 10 million
* Number of galaxy groups in the visible universe = 25 billion
* Number of large galaxies in the visible universe = 350 billion
* Number of dwarf galaxies in the visible universe = 7 trillion
* Number of stars in the visible universe = 30 billion trillion (3x10²²)
https://academickids.com/encyclopedia/index.php/Timelines
- Orders of magnitude (length) – Comparison of a wide range of lengths
- light years
- Orders of magnitude (time) – Comparison of a wide range of timescales
Astronomy is the scientific study of celestial objects.
Main article: Observational astronomy
Main article: Theoretical astronomy
- Outline of astronomy
- Lists of astronomical objects
- Outline of space science – Overview of and topical guide to space science
- Glossary of astronomy – List of definitions of terms and concepts commonly used in the study of astronomy
- Universe
- Observable universe
- Extragalactic astronomy
- superclusters,
- List of superclusters
- List of galaxy groups and clusters
- List of open clusters
- List of globular clusters
- Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure
- galactic astronomy.
- Galaxy formation and evolution
- Galaxy
- Galaxy groups and clusters
- Galaxy cluster
- Galaxy filament
- Galaxy group
- origin of galaxy clusters
- and superclusters.
- Outline of galaxies
- Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure
- List of nearest galaxies
- List of largest galaxies
- Low surface brightness galaxy
- ASTROPHYSICS: Applying the laws of physics in space
- ASTROMETRY: Mapping celestial bodies
- ASTROGEOLOGY: Examining rocks, terrain, and material in space
- ASTROBIOLOGY: Searching for life outside Earth
And we can categorize it into 17 branches of astronomy.
Astrophysics applies the principles of physics to astronomy.
- 1)ASTROPHYSICS – How the laws of physics apply to stars and celestial bodies.
- 2)COSMOLOGY – How the universe was created, evolved, and its ultimate fate.
- 3)SPECTROSCOPY – How light reflects, absorbs, and transfers between matter.
- 4)PHOTOMETRY – How luminous astronomical objects are in space based on electromagnetic radiation.
- 5)HELIOPHYSICS – How the sun’s constant and dynamic radiation affects its surroundings in space.
- 6)HELIOSEISMOLOGY – How the interior structure and dynamics of stars are composed by observing waves from their surface.
- 7)ASTEROSEISMOLOGY – How to study the internal structure of stars by observing their oscillations.
ASTROMETRY
- 8)ASTROMETRY – How celestial bodies are positioned and move in space.
- 9)PLANETOLOGY – How planets form in the solar systems including their composition and dynamics in history.
- 10)EXOPLANETOLOGY – How many and where planets exist outside our solar system.
ASTROGEOLOGY
- 11)ASTROGEOLOGY – How geology relates to celestial bodies like moons, asteroids, meteorites and comets.
- Asteroseismology - is the study of oscillations in stars.
- Helioseismology - is the study of the structure and dynamics of the Sun through its oscillations.
- 12)AREOLOGY – How geology is composed on Mars.
- 13)SELENOGRAPHY – How physical features on the moon formed such as lunar maria, craters, and mountain ranges.
- 14)EXOGEOLOGY – How geology relates to celestial bodies like moons, asteroids, meteorites, and comets.
ASTROBIOLOGY
- 15)ASTROBIOLOGY -How life (including extraterrestrials) in the universe evolved, originated, and what will be its fate.
- 16)EXOBIOLOGY – How likely and where is life in space.
- 17) ASTROCHEMISTRY – How to study substances in celestial bodies, stars, and interstellar space.
Physical geography ( Sub fields )
https://en.m.wikipedia.org/w/index.php?title=Celestial_navigation&diffonly=true
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- Anthropic principle – Hypothesis about sapient life and the universe
- Cosmography – Science that maps the universe
- Chronology of the universe – History and future of the universe
- Ultimate fate of the universe – Theories about the end of the universe
- Why there is anything at all