Pluto Might Be the Largest Dwarf Planet, After All For years Pluto has appeared to rank behind its fellow dwarf planet Eris in terms of diameter. New data, however, have cut Eris down to size Double Impact: Did 2 Giant Collisions Turn Uranus on Its Side? A pair of giant impacts early in solar system history could reconcile the dramatic tilt of Uranus with the equatorial orbit of its satellites Hot and Cold: Dwarf Planet Makemake Could Have Extreme Temperatures Side by Side Makemake may well have the most exotic name of the dwarf planets, and it now looks to be just as unusual on its surface Conjoined Comet: Hartley 2 May Have Formed from 2 Disparate Bodies The two ends of Comet Hartley 2 seem to have different compositions, hinting that the comet formed from the gentle merger of two parent objects Planetary Pretender: Asteroid Vesta Has Planet-Like Features NASA’s Dawn spacecraft is getting up close and personal with the giant asteroid, revealing rift valleys, mountainous uplifts and a belt of grooves near its equator Mercury Takes Shape in Color and Monochrome Maps The Messenger orbiter has just passed its first Mercury solar day–about 176 Earth days–on the job, an important milestone in its imaging campaign

Double Impact: Did 2 Giant Collisions Turn Uranus on Its Side? A pair of giant impacts early in solar system history could reconcile the dramatic tilt of Uranus with the equatorial orbit of its satellites

Hot and Cold: Dwarf Planet Makemake Could Have Extreme Temperatures Side by Side Makemake may well have the most exotic name of the dwarf planets, and it now looks to be just as unusual on its surface

Conjoined Comet: Hartley 2 May Have Formed from 2 Disparate Bodies The two ends of Comet Hartley 2 seem to have different compositions, hinting that the comet formed from the gentle merger of two parent objects

Planetary Pretender: Asteroid Vesta Has Planet-Like Features NASA’s Dawn spacecraft is getting up close and personal with the giant asteroid, revealing rift valleys, mountainous uplifts and a belt of grooves near its equator

Mercury Takes Shape in Color and Monochrome Maps The Messenger orbiter has just passed its first Mercury solar day–about 176 Earth days–on the job, an important milestone in its imaging campaign