About ESA
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.
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Space in Member States
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Germany
Austria
Belgium
Denmark
Spain
Estonia
Finland
France
Greece
Hungary
Ireland
Italy
Luxembourg
Norway
The Netherlands
Poland
Portugal
Czechia
Romania
United Kingdom
Slovenia
Sweden
Switzerland
Science & Exploration
Exploring our Solar System and unlocking the secrets of the Universe
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Enabling & Support
Making space accessible and developing the technologies for the future
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Comets and how the Solar System formed
Comets and how the Solar System formed
The Solar System formed about 4.6 billion years ago when a cloud of gas and dust started to collapse. A disc of material formed around the early Sun, the particles of which collided and joined together, growing increasingly larger and larger, until they formed planets, their moons and millions of asteroids and comets.
Over billions of years the planets have undergone many changes, but comets have retained many clues from the Solar System’s youth. As they spend most of their time far from the Sun in a ‘deep freeze’ their matter preserves the original material of the primitive nebula, helping us look back to the very infancy of the Solar System.
In 1986, ESA’s Giotto mission achieved the first close encounter of a comet, passing within 600 km of Comet Halley. Giotto, a pioneer in comet science, provided us with the first ever images of a comet’s nucleus.
Ground-based observatories, Giotto, and NASA’s Deep Impact and Stardust spacecraft that have made close flybys of comets since, have together shown that comets contain complex organic molecules rich in carbon, hydrogen, oxygen and nitrogen – essential ingredients for life. With Rosetta, scientists expect to be able to answer whether cometary impacts, very common in the early Solar System, brought large quantities of water to Earth, creating the conditions for life to form and evolve.
