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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The Cosmic Microwave Background, the relic radiation from the Big Bang, permeates the whole Universe in all directions. Today, it appears much colder than it used to be when it started its long cosmic journey; the CMB is in fact recognisable by its very low temperature: 2.7 Kelvin (or about 270º C below zero). However, the temperature of the CMB radiation is not completely uniform. There are tiny variations, or fluctuations, which carry information about the initial conditions of the Universe in which this radiation was liberated. These small variations of the CMB temperature reflect the existence in the primordial soup of the first seeds of the structures, such as galaxies, that we observe in our Universe today.
Planck will be able to measure temperature fluctuations about a million times smaller than one degree - better than any predecessor mission of its kind.