Dawn lights on Ceres


This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA: Dwarf planet Ceres continues to puzzle scientists as NASA’s Dawn spacecraft gets closer to being captured into orbit around the object. The latest images from Dawn, taken nearly 29,000 miles (46,000 kilometers) from Ceres, reveal that a bright spot that stands out in previous images lies close to yet another bright area.

“Ceres’ bright spot can now be seen to have a companion of lesser brightness, but apparently in the same basin. This may be pointing to a volcano-like origin of the spots, but we will have to wait for better resolution before we can make such geologic interpretations,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.

Ceres is thought to be covered in an ice crust and there is much speculation about the source of the brightness.  There is not enough light available for these to be reflections. Eruptions of what lies underneath through the ice crust is one theory. The Mission Director has a journal at the Dawn blog:

Dawn is showing us exotic scenery on a world that dates back to the dawn of the solar system, more than 4.5 billion years ago. Craters large and small remind us that Ceres lives in the rough and tumble environment of the main asteroid belt between Mars and Jupiter, and collectively they will help scientists develop a deeper understanding of the history and nature not only of Ceres itself but also of the solar system.  …..

….. Dawn is in the vicinity of Ceres and is not leaving. The adventurer has traveled more than 900 million miles (1.5 billion kilometers) since departing from Vesta in 2012, devoting most of the time to using its advanced ion propulsion system to reshape its orbit around the sun to match Ceres’ orbit. Now that their paths are so similar, the spacecraft is receding from the massive behemoth at the leisurely pace of about 35 mph (55 kilometers per hour), even as they race around the sun together at 38,700 mph (62,300 kilometers per hour). The probe is expertly flying an intricate course that would be the envy of any hotshot spaceship pilot. To reach its first observational orbit — a circular path from pole to pole and back at an altitude of 8,400 miles (13,500 kilometers) — Dawn is now taking advantage not only of ion propulsion but also the gravity of Ceres. On Feb. 23, the spacecraft was at its closest to Ceres yet, only 24,000 miles (less than 39,000 kilometers), or one-tenth of the separation between Earth and the moon. Momentum will carry it farther away for a while, so as it performs the complex cosmic choreography, Dawn will not come this close to its permanent partner again for six weeks. Well before then, it will be taken firmly and forever into Ceres’ gentle gravitational hold. 


Ceres (minor-planet designation 1 Ceres) is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. It is composed of rock and ice, is 950 km (590 mi) in diameter, and contains approximately one third of the mass of the asteroid belt. It is the only dwarf planet in the inner Solar System and the only object in the asteroid belt known to be unambiguously rounded by its own gravity. It was the first asteroid to be discovered, on 1 January 1801 by Giuseppe Piazzi in Palermo, though at first it was considered to be a planet. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest it is too dim to be seen with the naked eye except under extremely dark skies.


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