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
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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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One effect of a coronal mass ejection (CME) is a sudden decrease in the number of galactic cosmic rays detected, called the Forbush decrease after the scientist who first described it. During the passage of the CME (depicted as the pale swath in the middle graphic), it acts like a protective bubble, temporarily sweeping aside the cosmic rays (depicted as the white flecks) and shielding the planet or spacecraft such that the impact of cosmic rays is reduced. Typically a rapid decrease is observed, with a more gradual recovery over the coming days or longer, depending on the speed and size of the CME and the intensity of its associated magnetic field.
The graphic gives a representation and is not to scale.