Close encounters of another kind?   Comparative sizes of asteroids.   This artist's impression shows how the families of asteroids follow the orbits of their prototypes. Amors cross Mars’ orbit but do not cross Earth’s. It is the Apollo asteroids that cross Earth’s orbit. There are also the Atens. These asteroids spend most of their time inside Earth’s orbit, crossing it briefly before disappearing back into the glare of the Sun.   The Haughton meteorite impact crater, on Devon Island, Nunavut, in the Canadian high arctic, is 20 km in diameter and formed 23 million years ago. It is one of the highest-latitude terrestrial impact craters known on land (75°22'N, 89°41'W). It lies in the "frost rubble zone" of the Earth, i.e., in a polar desert environment and is the only crater known to lie in such an environment. Photo: NASA, Haughton-Mars Project 2001   In a rare celestial spectacle, two comets were observed plunging into the Sun's atmosphere in close succession, on 1 and 2 June 2000. This unusual event on Earth's own star was followed on 2 June 2000 by a likely unrelated but also dramatic ejection of solar gas and magnetic fields on the southwest (or lower right) limb of the Sun. Release date: 4 September 2003