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  2. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    When applied to samples of multiple stars, the uncertainty can be reduced; the uncertainty is inversely proportional to the square root of the sample size. [ 11 ] Moving cluster parallax is a technique where the motions of individual stars in a nearby star cluster can be used to find the distance to the cluster.

  3. Cosmological principle - Wikipedia

    en.wikipedia.org/wiki/Cosmological_principle

    In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course ...

  4. Anthropic principle - Wikipedia

    en.wikipedia.org/wiki/Anthropic_principle

    In cosmology, the anthropic principle, also known as the observation selection effect, is the proposition that the range of possible observations that could be made about the universe is limited by the fact that observations are possible only in the type of universe that is capable of developing intelligent life.

  5. Lambda-CDM model - Wikipedia

    en.wikipedia.org/wiki/Lambda-CDM_model

    The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components: a cosmological constant, denoted by lambda (Λ), associated with dark energy; the postulated cold dark matter, denoted by CDM; ordinary matter.

  6. Big Bang nucleosynthesis - Wikipedia

    en.wikipedia.org/wiki/Big_Bang_nucleosynthesis

    Without major changes to the Big Bang theory itself, BBN will result in mass abundances of about 75% of hydrogen-1, about 25% helium-4, about 0.01% of deuterium and helium-3, trace amounts (on the order of 10 −10) of lithium, and negligible heavier elements. That the observed abundances in the universe are generally consistent with these ...

  7. Friedmann equations - Wikipedia

    en.wikipedia.org/wiki/Friedmann_equations

    The Hubble parameter can change over time if other parts of the equation are time dependent (in particular the mass density, the vacuum energy, or the spatial curvature). Evaluating the Hubble parameter at the present time yields Hubble's constant which is the proportionality constant of Hubble's law.

  8. Outline of astronomy - Wikipedia

    en.wikipedia.org/wiki/Outline_of_astronomy

    The following outline is provided as an overview of and topical guide to astronomy: Astronomy – studies the universe beyond Earth, including its formation and development , and the evolution, physics , chemistry , meteorology , and motion of celestial objects (such as galaxies , planets , etc.) and phenomena that originate outside the ...

  9. List of unsolved problems in astronomy - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    A sample of 229 nearby "thick" disk stars has been used to investigate the existence of an age-metallicity relation in the Galactic thick disk and indicates that there is an age-metallicity relation present in the thick disk. [13] [14] Stellar ages from asteroseismology confirm the lack of any strong age-metallicity relation in the Galactic ...