HDl7l56b orbits this star so close to its parent star (8 to 37 million kilometres), and absorbs so much heat that its night side glows permanently hot. The exoplanet takes 21.2 days to orbit the star (much longer than the previous record), and has a highly elongated orbit (eccentricity = 0.67).

Our solar system is not the only one with an asteroid belt. Astrophysicists using the Spitzer Space Telescope found evidence of a similar but much more massive belt around a star called HD69830, 41 light years away in the constellation Puppis. Collisions are thought to occur in this belt every 1000 years or so.

Note that according to the IAU definition of a planet, a planet must orbit a star, be massive enough to have a spherical shape, and have cleared the neighbourhood of its orbit of any other objects. For now, this definition only applies to our own solar system and to exoplanets. In recent years there have been reports of free-floating planetary-mass objects (ones not orbiting any star), sometimes called 'rogue planets' or 'interstellar planets'. For now, such objects are outside the working definition of 'planet'.

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