Home / Topics / Gravitation & Orbits
Galaxy and cosmic structure
Advanced
Gravity builds stars, galaxies and clusters from small density differences.
Tiny initial density differences in the early universe grew by gravity into stars, galaxies and clusters, forming a cosmic web of filaments and voids.
Simulations like Millennium reproduce it.
Dark matter provides the scaffold.
In more detail
Galaxies and cosmic structures form under gravity from small density fluctuations in the early universe. Dark matter provides much of the gravitational pull that drives this growth.
Real-world uses
- Simulations of galaxy formation help interpret telescope observations.
- Mapping large-scale structure tests cosmological models.
- Cosmologists simulate how gravity turns tiny density differences into galaxies and clusters over billions of years.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
How did galaxies form?
Gravity amplified small density differences, pulling gas and dark matter together over billions of years.
Is gravity the only force involved?
Gravity dominates on large scales, while gas physics and star formation matter on smaller scales.
What starts the process of structure formation?
Small density variations in the early universe, which gravity amplified into the structures we see today.
Related topics in Gravitation & Orbits
Inertial vs gravitational mass · Equivalence principle · Orbital precession · Space elevators and tethers · Gravity on other planets · Spacecraft launch energy