Knowra Galactic astronomy Galactic astronomy Galactic astronomy studies the Milky Way’s structure, contents, formation, and evolution, using observations and physical models to explain how the Galaxy works and changes over time.
Milky Way : The barred spiral galaxy containing the Solar System, hundreds of billions of stars, gas, dust, and dark matter. It is the Galaxy whose structure and history galactic astronomy investigates.
Parallax : The apparent shift in an object’s position when viewed from different locations. Annual stellar parallax provides direct distances to nearby stars in the Milky Way.
Galaxy formation : The growth of galaxies from early density fluctuations through gas accretion, star formation, and mergers. Milky Way history is one nearby case of the broader process of galaxy formation.
Stellar evolution : The changes in a star’s structure, brightness, and composition over its lifetime. Interpreting Galactic stars requires knowing how their observable properties change with age.
Dark matter : Matter inferred from gravitational effects that does not emit, absorb, or reflect detectable light. Its distribution in the Milky Way remains uncertain despite its influence on stellar and satellite motions.
Galactic coordinate system : A coordinate system that locates objects by longitude and latitude relative to the Milky Way’s plane and center. It gives astronomers a natural frame for mapping objects across the Galaxy.
Proper motion : The angular change in a star’s position across the sky over time. Combined with distance, it reveals transverse stellar velocities and Galactic orbits.
Lambda-CDM model : The cosmological model in which cold dark matter and dark energy shape cosmic expansion and structure formation. It predicts that the Milky Way assembled through growth and mergers within a dark matter halo.
Star formation : The process by which dense regions of interstellar gas collapse to form stars. Mapping young stars reveals where the Milky Way is actively building new stellar populations.
Galactic center : The central region of the Milky Way, containing Sagittarius A* and densely packed stars and gas. Dust and crowding complicate measurements of the Galaxy’s central structure and history.
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