LifePairs of habitable worlds could throw microbes at each other Some exoplanet systems have planets a fifth as close together as Earth is to Mars, a factor that could drive interplanetary fraternisation ¿ìè¶ÌÊÓÆµ
SpaceHot Jupiters may have formed through planetary billiards The first exoplanets found were gas giants orbiting close to their stars – a study suggests they could be built from collisions of several smaller planets ¿ìè¶ÌÊÓÆµ