Astronomy chapter 1

Subdecks (1)

Cards (92)

  • All matter in the Universe is organised in structures, which form a hierarchy
  • Structure-scale ladder
    Sequence of structures of different scales from the greatest down to the smallest
  • Worlds based on size
    • Megaworld (from Greek megas - great, grandiose)
    • Macroworld (Greek makros - big, large)
    • Microworld (Greek mikros - small)
  • Objects in the Megaworld
    • Stars
    • Planets
    • Galaxies
  • Objects in the Macroworld
    • Objects surrounding us in everyday life, objects commensurate to us
  • Objects in the Microworld
    • Elementary particles
    • Atoms
    • Molecules
    • Cell
    • Chromosome
  • Living objects can be referred both to macro- and microstructures depending on their size
  • Structure-scale ladder
    • Observable Universe
    • Cellular structure (voids, walls, superclusters of galaxies)
    • Clusters and groups of the galaxies
    • Galaxies, quasars and galactic nuclei
    • Stellar clusters in galaxies
    • Stars, planetary systems
    • Cosmic bodies: planets (incl. the Earth), comets, asteroids, etc.
    • Geological structures (tectonic plates, continents, islands, mountains, etc.)
    • Macroscopic objects (including us)
    • Microscopic objects (cells, genes, etc.)
    • Molecules
    • Atoms
    • Atomic nuclei and elementary particles
    • Quarks, leptons, messenger particles
  • Light-year
    Distance travelled by light in vacuum in one year, approximately 10 million million kilometres = 10 to the power 13 km
  • Cosmological horizon
    Border of the observable Universe, beyond which matter is not accessible to observations
  • In a static Universe, the cosmological horizon would be situated at the distance that light travels within the age of the Universe, which is about 46 billion light-years in our expanding Universe
  • Distribution of galaxies on the sky is both regular and non-regular
  • Cosmic web
    Galaxies form cells similar to a honeycomb, with walls formed by galaxies and empty spaces (voids) inside the cells. Majority of galaxies are concentrated in the intersections of walls and in the knots where three walls intersect
  • Clusters of galaxies
    Nearly spherical structures consisting of hundreds and thousands of galaxies
  • Groups of galaxies
    Non-numerous clusters of galaxies, such as the Local Group consisting of the Milky Way and Andromeda Galaxy
  • Galaxies
    • Stellar systems consisting of billions of stars, gas and dust. 9/10 of the galactic material exists in a hidden, invisible form
  • Masses of galaxies vary from 10^9 to 10^12 solar masses, with the Milky Way being close to the upper limit
  • Sizes of galaxies (their visible parts) usually vary from 3 to 300 thousand light-years
  • Types of galaxies
    • Spiral
    • Spherical or elliptical
    • Irregular asymmetric
  • Quasars
    Quasi-stellar objects, which are the most distant objects in the observable Universe and are likely the nuclei of distant galaxies in a highly active state
  • Types of stellar clusters
    • Globular clusters
    • Open clusters
  • Globular clusters
    • Spherical objects containing millions of stars, the oldest formations in the Milky Way with an age of 10-12 billion years
  • Open clusters
    • Contain tens, hundreds or thousands of stars, some are relatively young (e.g. Pleiades at 60 million years)
  • Stars are born in groups and clusters, not one at a time
  • Types of stars
    • Regular stars
    • Compact stars (white dwarfs, neutron stars, black holes)
  • Sizes of regular stars vary from slightly smaller than the Sun to enormous sizes of supergiants, while compact stars range from several kilometres to several thousand kilometres
  • Planetary systems
    Apart from the Solar system, hundreds of multiplanetary systems with at least two confirmed exoplanets are known
  • The star with the most confirmed planets is the Sun with 8, while Kepler-90 and HD 10180 have the most exoplanets with 7 each
  • Cosmic bodies
    • Planets
    • Comets
    • Asteroids
    • Small planets
  • The diameter of the Earth is about 13,000 km
  • Macroscopic bodies are all the objects around us, consisting of a very large number of molecules
  • Microscopic bodies
    Associations of molecules, such as cells and their components
  • Molecules
    • Vary in size from the simplest two-atomic molecules to complex polymeric macromolecules with molecular weights in the hundreds of thousands
  • Atom
    Consists of a compact nucleus and an electron shell, with the size determined by the electron shell
  • The word "atom" comes from the Greek word "atomos" meaning indivisible, but atoms were later found to be composed of subatomic particles
  • Subatomic particles
    • Elementary particles (primary, indivisible)
    • Composite particles
  • Initially only protons, neutrons, electrons and photons were considered elementary particles, but more were discovered over time
  • Types of subatomic particles
    • Elementary particles
    • Composite particles
  • Elementary particles
    Primary, indivisible particles, of which all the matter consists
  • Till the beginning of 1930s the only known representatives of elementary particles were proton, neutron, electron, and photon