Laniakea: Our Supercluster of Galaxies

Laniakea Supercluster

Discovered in 2014 thanks to the work of Brent Tully and his team, Laniakea, which means "immense sky" in Hawaiian, is the galactic supercluster to which our Milky Way belongs. This supercluster contains about 100,000 galaxies spread over a distance of 520 million light-years and has an estimated total mass of 10¹⁷ solar masses. This vast ensemble is held together by gravitational forces that organize galaxies into a complex network of filaments and voids, connecting the large structures of the observable universe.

Structure and Dynamics

Laniakea is defined by gravitational flows that converge towards a central point called the Great Attractor. These flows indicate the direction in which galaxies are attracted under the influence of gravity. Thanks to observations of the distribution of galaxies and radial velocities, it is possible to map the boundaries of Laniakea and understand how structures form on a large scale in the universe.

The identification of Laniakea has redefined our perception of our position in the universe. While our Milky Way seems isolated at first glance, it is actually connected to a much larger cosmic network. This discovery also highlights the importance of gravitational interactions in the formation and evolution of galactic structures.

Superclusters Neighboring Laniakea

• Shapley Supercluster
• Coma Supercluster
• Coma Berenices Supercluster
• Hydra-Centaurus Supercluster
• Pavo-Indus Supercluster
• Perseus-Pisces Supercluster

These superclusters, although physically distinct, sometimes interact gravitationally with each other on a cosmic scale. This makes the universe a vast dynamic web where gravitational forces shape the distribution of galaxies.

10 Million Superclusters in the Observable Universe

The exact number of superclusters contained in the observable universe is difficult to determine precisely, as it depends on the exact definition of what is called a supercluster, as well as the limits of current observations. However, estimates can be made by combining cosmological data, the distribution of galaxies, and theoretical models.

• Estimates of the Number of Superclusters
• Average Density of Superclusters

  Typical superclusters have a size of 100 to 500 million light-years and contain on the order of 10⁴ to 10⁵ galaxies.

  Considering the size and average spacing of superclusters (a few hundred million light-years between them), it can be estimated that there are approximately 10 million superclusters in the observable universe.

These superclusters, although physically distinct, interact gravitationally with each other on a cosmic scale. This makes the universe a vast dynamic web where gravitational forces shape the distribution of galaxies.