Object profile · CERES
Ceres
Dwarf planet · Main asteroid belt
A water-rich dwarf planet whose bright salts record activity inside an ancient small world.
- Atlas data reviewed
- Editorial stage
- Published
- Visibility
- Public
Direct observationOfficial NASA data mosaic assembled from Dawn Framing Camera observations.
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA ↗What this world is
Ceres is both the largest object in the asteroid belt and the nearest dwarf planet. Dawn showed it is not simply a dead rock: water ice, salts and recent geological activity connect its surface to materials below.
Why it looks this way now
No mission is currently orbiting Ceres. Dawn's archive remains the primary close-range evidence, while telescope observations continue to refine context.
Where it sits
Ceres orbits between Mars and Jupiter in the main asteroid belt. It contains roughly a quarter of the belt's total mass.
Swipe sideways to inspect the full map
The blue marker places Ceres inside the dotted belt region, orbiting the Sun directly.
Mars is the inner reference orbit and Jupiter the outer one, bracketing the main belt.
Read the numbers
Reference values retain their units, context, evidence state and published uncertainty.
Physical measurements
- Mean radiusglobal mean
- 469.7kmCalculated measurementSmaller than Earth's Moon.
A global reference radius reconstructed from imaging, thermal data or occultation.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Massglobal mean
- 9.3835E20kgCalculated measurementFar below Earth's mass, yet enough gravity to become rounded.
Calculated from the motion of a spacecraft, moon or dynamical system.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Mean densityglobal mean
- 2.162g/cm³Calculated measurementA clue to the relative mixture of rock, water ice and voids.
Density is calculated from mass and volume; it does not reveal a unique interior by itself.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Reference gravitysurface
- 0.27m/s²Calculated measurementOnly a few percent of Earth's surface gravity.
A reference value derived from mass and radius.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Temperaturesurface
- -105°CScientific modelCold enough for volatile compounds to remain as surface ice.
A model-supported representative temperature, not a thermometer reading on the ground.
Approximate value
Representative equilibrium or surface temperature; local and seasonal conditions vary.
Orbit and rotation
- Average distancerelative to the Sun
- 2.770AUCalculated measurementBetween Mars and Jupiter.
The semi-major-axis reference summarizes an orbit whose actual distance changes.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Rotation periodrelative to distant stars
- 9.0742hCalculated measurementMeasured from repeating brightness or surface patterns.
A sidereal rotation period relative to distant stars.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
- Orbital periodrelative to the Sun
- 4.60Earth yearsCalculated measurementOne full season cycle lasts many human lifetimes.
Calculated from long-baseline astrometry and a fitted heliocentric orbit.
No uncertainty published in this source table
The selected summary source does not publish a compact uncertainty for this reference value.
Atmosphere and inside
Atmosphere
Ceres has an extremely tenuous, variable water-vapour exosphere rather than a stable weather-bearing atmosphere.
- Water vapourRelative abundance described; exact fraction not listed
Surface and interior
Ceres has a solid crust over a differentiated, water-bearing interior. Exact present-day liquid volumes remain uncertain.
- 1Rock-rich interior
Gravity and shape data support a differentiated interior rich in rock, but the exact layering remains model-dependent.
Scientific model - 2Ice- and brine-bearing shell
Minerals, gravity and young bright deposits indicate water ice and salty fluids within the crust.
Scientific model - 3Cratered crust
Dawn directly mapped craters, landslides, salt-rich bright deposits and cryovolcanic landforms.
Direct observation
How we know
Size comes from imaging, thermal data or occultation; orbit and rotation from repeated positions and brightness; mass only when gravity leaves a measurable trace.
- 01Calculated measurement
Spacecraft shape reconstruction
Images from changing viewpoints trace the limb and reconstruct global shape.
Where this method stops
Image coverage and viewing geometry are uneven.
- 02Calculated measurement
Gravity from orbital motion
The motion of a moon or spacecraft reveals the central body's gravitational parameter.
Where this method stops
The solution depends on orbit coverage and a dynamical model.
- 03Calculated measurement
Thermal radiometry and spectroscopy
Brightness at visible, infrared and thermal wavelengths constrains temperature, reflectivity and surface ices.
Where this method stops
Temperature and size can trade off against albedo, roughness and thermal assumptions.
- 04Calculated measurement
Long-baseline astrometry
Repeated sky positions over years are fitted to a heliocentric orbit.
Where this method stops
Long-period distant objects need many years of observations and future values remain predictions.
- 05Calculated measurement
Rotational light curve
Repeating brightness changes reveal a candidate rotation period.
Where this method stops
Shape, surface markings and viewing angle can create aliases or double-peaked solutions.
Evidence key
- Direct observation
- An instrument or sample recorded the phenomenon, with processing still disclosed.
- Calculated measurement
- Observed motion or signal is converted into a physical quantity using equations and reference constants.
- Scientific model
- A tested interpretation that fits observations but is not directly imaged or sampled.
- Vastward explanation
- Original beginner-facing synthesis, traceable to the source records but not itself a measurement.
- Artist visualization
- An interpretive image, not observational evidence.
Missions and instruments
Dawn
The only spacecraft to orbit Ceres mapped its surface, gravity, composition and evidence for brines.
Official mission ↗- Dawn Framing CameraGlobal shape, geology, color ratios and surface landmarks.
- Visible and Infrared SpectrometerMineral and ice signatures across Ceres.
- Gamma Ray and Neutron DetectorNear-surface elemental abundances and hydrogen.
Official source trail
Links below are the exact records used for this profile. Access dates are retained with the content.
- 01
NASA Science · official-page
Ceres Facts
- Source updated
- No source update date published
- Access checked
- 2026-07-31
- 02
NASA Jet Propulsion Laboratory, Solar System Dynamics · dataset
JPL Small-Body Database Lookup: 1 Ceres
- Source updated
- No source update date published
- Access checked
- 2026-07-31
- 03
NASA Science · official-page
Dawn at Ceres
- Source updated
- No source update date published
- Access checked
- 2026-07-31
- 04
NASA Science · image
High Resolution Ceres View
- Source updated
- No source update date published
- Access checked
- 2026-07-31
Continue exploring
Atlas is a starting point. Use these relationships to move into explanation, experiment and mission thinking.
Why is it a dwarf planet?
Use Ceres to separate roundness, orbit and orbital clearing—the three ideas behind the classification.
academyCompare the small worlds
Place radius, density and sunlight side by side without pretending every value is equally certain.
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