Despite this, it is not directly observable through any known means of detection. This is due to the fact that dark matter does not emit or interact with electromagnetic radiation, such as light, making it extremely difficult to spot. Instead, its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe.

For example, the motion of galaxies within clusters and the observed rotational speeds of galaxies suggest that there must be far more mass present than what we can see. The discrepancy between the calculated mass and the observed mass can be explained by the presence of dark matter. The gravitational effects observed cannot be explained by the accepted theories of gravity unless there is significantly more matter present than we can see.

Moreover, the Cosmic Microwave Background (CMB) also provides evidence for dark matter. Tiny fluctuations in the CMB's temperature indicate regions of different densities in the early universe, which later evolved into the large-scale structure we see today. Without dark matter, there would not have been enough mass in the universe for structures like galaxies and clusters of galaxies to form.

The exact composition of dark matter is still unknown. Many scientists believe that dark matter may be made up of undiscovered subatomic particles, while others think it could be made of macroscopic objects, such as black holes. Despite the many unknowns, the study of dark matter is a crucial aspect of current astrophysical research.