THE picture shows Ceres, the largest object in the asteroid belt, as seen a few days ago from Dawn, an American spacecraft that is en route there. Ceres’s gravity is strong enough to make it round, like a planet. And it probably has a core and a mantle, like Earth (though the core is thought to be rocky, and the mantle icy). It may even have a thin atmosphere.

But Ceres is not a planet. It was classified as such in 1801, when it was discovered, but soon after it was spotted astronomers started finding other objects in the junkyard of rock and ice that is now called the asteroid belt. The idea of calling all of them planets began to look silly, and so Ceres was quietly demoted. These days it is classed as a “dwarf planet”, one of at least five in the solar system.

The most famous of them is Pluto, which was, in 2006, demoted from full planethood by the International Astronomical Union, amid much wailing and gnashing of teeth. Pluto now is merely the biggest object in the Kuiper Belt, a second group of asteroids, which extends far beyond the orbit of Neptune, the most distant of the true planets.

Despite its demotion, Pluto is due a visit, too. On January 25th New Horizons, another American spacecraft, which was launched a few months before the reclassification, snapped its first pictures of its quarry (sadly unavailable as The Economist went to press). But the craft is travelling far too fast to have any hope of stopping. On July 14th it will whizz past the former planet, collecting as much data as possible before it goes careering off into the void.

Neither Ceres nor Pluto has been visited before, though Dawn did visit another big asteroid, Vesta, in 2011. Both are the cosmic equivalent of builder’s rubble, left over from the construction of the solar system 4.6 billion years ago. These days, the best place to look for full-blown planets is in solar systems other than Earth’s. More than 1,800 such exoplanets have been discovered since the first turned up in 1992. On January 26th, a group of astronomers led by Tiago Campante of Birmingham University, in Britain, announced the discovery of five rocky planets around Kepler-444, a star about 117 light-years from Earth that is smaller, dimmer and more orange than the sun.

The most striking thing about this star, though, is its immense age. Using a technique called asteroseismology, which measures stellar pulsations, the researchers estimate this to be 11.2 billion years, give or take a billion. That is ancient indeed. The universe itself is only 13.8 billion years old.

Assuming the planets are the same age as their star (likely but not definite; it is just conceivable they have arrived from elsewhere), that suggests planet formation began not long after the Big Bang. Kepler-444’s worlds look uninhabitable. All orbit scorchingly close to their parent star. But if other, similarly ancient worlds exist in more temperate climes, then life may have been possible in the universe almost from the beginning.