Rotation phase
\[\theta(t)=\theta_0+\frac{2\pi t}{P_{\mathrm{rot}}}\]
The displayed spin angle advances from the body's rotation period P_rot. Retrograde rotation is represented by the sign of P_rot.
Terrestrial planet
Mercury
The innermost planet is a dense, cratered world with almost no atmosphere and extreme temperature contrast.
Mercury: loading local 3D asset.
Physics Snapshot
What Scientists Watch
Classification: Inner terrestrial planet. Mercury through Mars are inner rocky worlds; Jupiter through Neptune are outer giants.
- High iron fraction suggests a large metallic core relative to its radius.
- Solar tides and general relativity measurably shape its perihelion precession.
- Permanently shadowed polar craters can trap volatile ice despite the planet's proximity to the Sun.
Exploration note: Mariner 10, MESSENGER, and ESA-JAXA BepiColombo provide the main spacecraft record.
Atmosphere and oceans
Gases, temperature, and liquids
Interpretation note
How to read these values
Rocky worlds list surface conditions directly. Jupiter, Saturn, Uranus, and Neptune do not have hard surfaces, so temperature and pressure are referenced to atmospheric levels such as the 1-bar cloud region.
Ocean status separates the planet itself from its moons. Several outer-planet moons are major ocean-world targets even when the parent planet has no surface ocean.
3D asset view
Rotatable planet model
Mercury: loading local 3D asset.
This viewer loads the local asset-backed model for Mercury and applies the sidereal axis tilt and relative rotation direction for study. Drag to rotate, wheel to zoom, and open full screen for close inspection.
Elevation and relief
Topography map notes
- Caloris Basin, Rembrandt basin, and globally distributed impact plains dominate the relief map.
- Lobate scarps cut across craters and plains, recording planetary contraction as the large metallic core cooled.
- Permanently shadowed polar craters are cold traps where radar-bright ice deposits are plausible.
Interior and field
Core, mantle, and magnetism
Orbital characteristics
Detailed orbit solution
Physical characteristics
Bulk properties and rotation
Atmosphere profile
Pressure, composition, and temperature
Field review
Magnetic field, core behavior, and crater context
- Mercury has a real global magnetic field, but it is weak compared with Earth and offset northward from the planet's center.
- Its magnetosphere is compressed by the solar wind, so reconnection and particle precipitation can be studied close to the Sun.
Caloris BasinRembrandtRaditladiEminescu
Moon catalog
Moons Available
Confirmed count: 0
No natural moons confirmed.
Data note: rotation values are sidereal periods. For solar orbits this guide uses perihelion and aphelion; those are the Sun-orbit equivalents of closest and farthest orbital distance. Gravity is surface or equatorial gravity for rocky planets and a reference-level value for giant planets, so rounded fact sheets may differ slightly. Moon counts can change when new satellites are confirmed.
Data basis
How these values are normalized
Orbital elements are presented in a J2000-style reference format. Rotation values use sidereal periods unless a solar day is explicitly named. For giant planets, pressure, temperature, and gravity are reference-level values because there is no solid surface to stand on.
Audit note
How to read discrepancies
Compact summary boxes, environment notes, and detailed fact tables are now aligned to the same field guide data blocks. This consistency pass was updated on May 5, 2026. Small differences can still appear when a quantity is rounded for readability, when a rocky-planet surface value is contrasted with a giant-planet reference level, or when moon counts change after new confirmations.
Mathematical model
Planet rotation and scale model
Planet meshes are procedural study models: radius, axial tilt, and rotation come from catalog fields, while surface textures are visual aids. The mathematical model does not infer planet shape from a picture.
Axial tilt
\[\mathbf{r}_{\mathrm{tilted}}=R_z(\varepsilon)\,\mathbf{r}_{\mathrm{body}}\]
The spin axis is tilted by an explicit obliquity epsilon. The proof is a rigid-body rotation matrix, not an artist-drawn axis.
Scale contract
\[R_{\mathrm{scene}}=k\,R_{\mathrm{catalog}}\]
Scene radius is a scalar multiple of catalog radius unless the user chooses a readability mode. The page states when visual radius is bounded so the model is not mistaken for exact visual scale.
Verification standard: the rendered object must be reproducible from stated equations, catalog parameters, or explicit geometric transforms. Visual reference images may inform presentation only; they are not the source of orbital positions, field vectors, accretion-disk gradients, timing, or engineering layout.
Limitations: browser scenes may use bounded scale, compressed distances, simplified two-body dynamics, schematic transfer curves, or educational approximations where full numerical ephemerides, CFD, finite-element models, or general-relativistic ray tracing are outside the page scope. Those simplifications are part of the model contract, not hidden image-based construction.