The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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Two dwarf galaxies, Draco (left) and Ursa Minor (right), as viewed by ESA’s Gaia satellite using information from the mission’s second data release.
Both are satellite galaxies of the Milky Way, held in orbit by our Galaxy’s gravity. There are a few dozen dwarf galaxies in orbit around the Milky Way. Each contains between 100 million to a few billion stars.
Using data from Gaia’s second release, astronomers have measured the motion of 12 satellite galaxies of our Milky Way. Surprisingly, the Draco and Ursa Minor galaxies seem to be moving on similar orbits, traveling together through space.
The view is not a photograph but was compiled by mapping the total density of stars detected by Gaia in each pixel.
Acknowledgement: Gaia Data Processing and Analysis Consortium (DPAC); A. Moitinho / A. F. Silva / M. Barros / C. Barata, University of Lisbon, Portugal; H. Savietto, Fork Research, Portugal; A. Helmi, Kapteyn Astronomical Institute, University of Groningen, The Netherlands;F. van Leeuwen, University of Cambridge, UK; P. Mc Millan, Lund Observatory, Sweden