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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This graph shows the altitude of stars in our Galaxy above or below the plane of the Milky Way against their velocity in the same direction, based on a simulation of a near collision that set millions of stars moving like ripples on a pond.
The snail shell-like shape of the pattern reproduces a feature that was first seen in the movement of stars in the Milky Way disc using data from the second release of ESA’s Gaia mission, and interpreted as an imprint of a galactic encounter.
The close encounter revealed by the Gaia data likely took place sometime in the past 300–900 million years, and the culprit could be the Sagittarius dwarf galaxy, a small galaxy containing a few tens of millions of stars that is currently in the process of being cannibalised by the Milky Way.
Full story: Gaia hints at our Galaxy’s turbulent life