The Smallest Planet?

  • Released Thursday, May 31st, 2012
  • Updated Wednesday, May 3rd, 2023 at 1:53PM
  • ID: 10979

Even though Vesta is only the size of Arizona, the asteroid may be a planet. New measurements taken by NASA's Dawn spacecraft, which arrived at Vesta in July 2011 and has orbited as close as 130 miles from the surface, show that beneath complex layers of rock lies a solid metal core. This distinct characteristic makes a strong case for Vesta's reclassification, as the separation of geologic material into crust, mantle and core layers is universal among the terrestrial planets in our solar system. Scientists argue Vesta could have grown to be a full-size planet, but the gravity of its massive neighbor Jupiter disrupted the process. The video below explores Vesta's landscape, history and prospects of being named a planet.

The rocky surface of Vesta hides a secret inside.

The rocky surface of Vesta hides a secret inside.

First spotted as a blur 200 years ago, Vesta's complex history is beginning to emerge more clearly.

Dawn's imagery of Vesta's surface revealed this set of three craters, nicknamed "Snowman."

Dawn's imagery of Vesta's surface revealed this set of three craters, nicknamed "Snowman."

Dawn's high-resolution data was used to create this virtual landscape of Vesta's south pole, showing mountains, cliffs and craters.

Dawn's high-resolution data was used to create this virtual landscape of Vesta's south pole, showing mountains, cliffs and craters.

Vesta's varied landscape, including a deep impact basin (blue) at its south pole, stands out in this false-color map of surface elevation.

Vesta's varied landscape, including a deep impact basin (blue) at its south pole, stands out in this false-color map of surface elevation.

Dawn will stay at Vesta until August 2012, when it will begin a three-year trip to Ceres, the largest asteroid. Who knows what it will find there?

Dawn will stay at Vesta until August 2012, when it will begin a three-year trip to Ceres, the largest asteroid. Who knows what it will find there?

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Credits

Please give credit for this item to:
Science@NASA and NASA's Goddard Space Flight Center
"Snowman" crater image courtesy of NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Virtual landscape image courtesy of NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
False-color map courtesy of NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Vesta size comparison image courtesy of NASA/JPL-Caltech/UCLA