The tiny planet, shaped more or less like a rugby ball and about 1,200 miles long, moves beyond the orbit of Neptune.
It rotates on its axis every 4 hours, giving it one of the fastest rotation speeds in the solar system, a release from the Spanish Foundation for Science and Technology said Thursday.
The frozen water that covers Haumea and its two satellites, Hi'iaka and Namaka, makes them shine in the darkness of space, astronomers say.
Scientists say they believe the two satellites could have been created by another object smashing into Haumea, which could also have started the rapid rotation of the dwarf planet and given it its soccer ball shape.
Haumea is the fifth dwarf planet in the solar system along with Pluto, Ceres, Eris and Makemake. Its existence was confirmed in 2005.
In Hawaiian mythology, Haumea is the goddess of fertility and birth, and Hi'iaka and Namaka are two of her daughters.