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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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
Go to topicA comet's structure includes the rock-ice nucleus, its atmosphere (coma), and the tails that stream out behind the comet as it approaches the Sun.
As a comet approaches the Sun its ices begin to sublimate. The gas escaping from the nucleus carries dust with it, creating the coma. As the solar wind streams around the coma it carries cometary particles and dust with it, leading to the formation of the comet's tails.
The ion tail contains ionised gas and dust and always streams directly away from the Sun. The dust tail, laced with microscopic dust particles, curves slightly in the direction of the comet's orbit.