Galaxy rotation curve
Videos
The rotation curve of a disc galaxy is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically
Comparison of rotating disc galaxies in the present day (left) and the distant Universe (right).
Dark matter
Videos
In astronomy and cosmology, dark matter is an invisible and hypothetical form of matter that does not interact with electromagnetic radiation, including light. Dark matter is implied by gravitational
Galaxy rotation curve
…curves observed are at significant variance with gravitational theory applied to the matter observed in a galaxy. Theories involving unobservable dark matter are the main postulated explanation of this discrepancy. Considering their mass distributions, the rotational/orbital speeds of galaxies/stars would…
Hubble close-up on the Coma Cluster
Gravitational lensing bends light around a massive object from a distant source. The orange arrows show the apparent position of the background source. The white arrows show the path of the light from the true position of the source.
The Bullet Cluster
November 2025 JWST observations confirmed an actively growing supermassive black hole within a "little red dot" galaxy named CANUCS-LRD-z8.6.