'2.5 million light-years away': NASA's Hubble Space Telescope discovers 36 dwarf galaxies orbiting Andromeda

Produced by Tarun Mishra

Mar 01, 2025, 03:20 PM

Andromeda’s Brightest Satellite Galaxies

NASA’s Hubble Space Telescope has identified 36 dwarf galaxies orbiting the Andromeda Galaxy. The images were compiled over more than 1,000 orbits of Earth to create a detailed study of these satellites.

Unexpected Diversity

The dwarf galaxies display varied movement patterns, some of which do not align with existing models of galaxy formation. Scientists aim to study these anomalies to understand Andromeda’s development.

Insights Into Galaxy Formation

Conventional theories suggest galaxies form within dark matter structures that pull in smaller satellite galaxies. The arrangement of these dwarf galaxies could offer new insights into this process.

Future Observations

Astronomers plan to take follow-up images in five years using Hubble or the James Webb Space Telescope. Comparing these images will help determine how these galaxies have moved and where they originated.

Star Formation

Some of the dwarf galaxies have continuously formed stars, contradicting existing simulations. Typically, satellite galaxies halt star formation unless influenced by a larger galaxy’s gravitational effects.

Orbital Alignment

Half of the observed dwarf galaxies orbit Andromeda in the same plane and direction, a pattern not expected under standard galaxy formation models. This alignment supports an alternative gravity theory known as MOND.

Andromeda’s History

Unlike the Milky Way, which has remained relatively undisturbed for billions of years, Andromeda appears to have undergone major mergers, influencing its mass and satellite system. This raises questions about using the Milky Way as a universal model for galaxy evolution.