The short answer: Dwarf planets vary widely, with masses ranging from about 9.4 × 1020 kg (roughly 2 × 1021 lb) for Ceres up to around 1.3 × 1022 kg for Pluto and Eris.
Dwarf planet weight by type
Dwarf planets orbit the Sun and are large enough to be nearly round, but they have not cleared their orbital paths. Their masses differ by more than an order of magnitude.
| Dwarf planet | Approximate mass |
|---|---|
| Ceres | about 9.4 × 10²⁰ kg |
| Haumea | about 4.0 × 10²¹ kg |
| Makemake | about 3.1 × 10²¹ kg |
| Pluto | about 1.3 × 10²² kg |
| Eris | about 1.6 × 10²² kg |
What affects dwarf planet weight
- Diameter. Larger dwarf planets generally contain far more material and so weigh more.
- Composition. Rocky bodies like Eris are denser and heavier than icy ones of similar size.
- Rock-to-ice ratio. The internal mix of rock and frozen volatiles strongly affects total mass.
- Moons. Studying a dwarf planet's moon helps astronomers calculate its mass more precisely.
- Measurement distance. Most dwarf planets are extremely far away, so masses are estimated and carry uncertainty.
How dwarf planet weight compares
Pluto, at roughly 1.3 × 1022 kg, is only about one-sixth the mass of Earth's Moon, while Ceres is lighter still at just a few percent of the Moon's mass.
Frequently asked questions
What is the heaviest dwarf planet?
Eris is the most massive known dwarf planet at roughly 1.6 × 10²² kilograms, slightly heavier than Pluto. Its higher density makes it the heavyweight of the group.
Is Pluto a dwarf planet?
Yes. In 2006 the International Astronomical Union reclassified Pluto as a dwarf planet because it has not cleared its orbit of other objects. Its mass is about 1.3 × 10²² kilograms.
How do scientists weigh a dwarf planet?
Astronomers measure a dwarf planet's mass mainly by observing the orbit of its moons or its gravitational effect on nearby bodies. Spacecraft flybys, like New Horizons at Pluto, refine these estimates.
