10 Hygiea size and scale context

10 Hygiea is the fourth-largest object in the asteroid belt. In 2019 the VLT's SPHERE instrument revealed it to be very nearly spherical, which would make it the smallest known dwarf planet — a body massive enough for gravity to pull it into a round shape, yet only about 430 kilometers across. Read its scale context, comparisons, and journey links on the canonical object page.

HyperionIrregular icy moon·360 km

MimasIcy moon·396 km

10 HygieaC-type asteroid / dwarf-planet candidate·434 km

ProteusSmall inner moon·436 km

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Between the smallest and the largest, perspective is everything.

About

Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.

Guides turn parts of that scale into curated essays, while focused views let you explore the same range through specific groups of objects.

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Between the smallest and the largest, perspective is everything.

About

Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.

Guides turn parts of that scale into curated essays, while focused views let you explore the same range through specific groups of objects.

Editorial

Solar System Planets From Electron to Atoms Stars To Scale Birth And Death Of Stars Black Holes To Scale

Views

Planets of the Solar System Stars of the Universe Black holes Subatomic scale

Open Scale of Space Browse all comparisons

Moons

Mimas

Mimas is a small icy moon of Saturn dominated by the enormous Herschel crater. NASA notes that the impact that made Herschel may have come close to shattering the moon, leaving one of the most disproportionate giant craters in the Solar System.

Scale fact396 kmdiameter

Object class: Icy moon
Mass: ~38 quadrillion tonnes
Host: Saturn
Estimated age: ~4.5 billion years
Composition: Mostly water ice
Temperature: ~75 K surface

Asteroids

10 Hygiea

Scale fact434 kmmean diameter

Object class: C-type asteroid / dwarf-planet candidate
Mass: ~0.000014 Earth masses
Estimated age: ~4.5 billion years
Composition: Carbonaceous rock and ice

Moons

Proteus

Proteus is Neptune's largest inner moon, a dark irregular body discovered by Voyager 2 in 1989. It keeps a box-like shape near the threshold where gravity would round it out, while its battered dark surface shows no clear sign of geological remodeling.

Scale fact436 kmmaximum extent

Object class: Small inner moon
Host: Neptune