The Hubble Space Telescope has observed the farthest active inbound comet ever seen, at a whopping distance of over 2.4 billion kilometres from the Sun.<br/>'<br/>Slightly warmed by the Sun, it has already begun to develop a fuzzy cloud of dust over 100,000 kilometres wide, called a coma, enveloping a tiny, solid nucleus of frozen gas and dust.<br/>'<br/>The comet, called 'K2' has been travelling for millions of years from its home in the frigid outer reaches of the solar system, where the temperature is about minus 262 degrees Celsius.<br/>'<br/>The comet's orbit indicates that it came from the Oort Cloud, a spherical region almost a light-year in diameter and thought to contain hundreds of billions of comets.