Mercury
OVERVIEW
] PLANETMercury is a terrestrial planet. It orbits the Sun at a mean distance of 0.38709927 . It has a mass of 0.06 and a mean radius of 0.38 · 2440 . It has been known since antiquity.
The smallest planet and the closest to the Sun, a cratered ball of rock with almost no atmosphere, where a single day lasts two of its years.
- WHAT IT IS
- Terrestrial planet
- HOW FAR
- 0.3871
- HOW BIG
- 0.38 · 2440
- ONE ORBIT TAKES
- 88
Its average distance from the Sun, not from Earth.
Its mean radius: half the width across.
One trip round the Sun.
THE MODEL
] CATALOGUED RADIUSCALCULATED · NOT AN OBSERVATION · CATALOGUED RADIUS · DENSITY 5.43 G/CM³ FROM MASS AND RADIUS · RADIUS 2440 KM · LIT FROM WHERE THE SUN IS · TURNING ABOUT ITS OWN POLE
Drawn from the catalogued radius and from the same properties the picture at the top of this page uses, at the distance a flight to it would stop. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, at their real positions and drawn from where the camera actually is — so the constellations are wrong, and that is the point. This is the sky from there, not the sky from here.
IMAGES
] 4 FRAMES- NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Public domain - NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Public domain - NASA
Public domain - NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State University/Carnegie Institution of Washington
Public domain
OBSERVING
] FROM WHERE YOU AREWhat it takes to see Mercury for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when Mercury is worth going out for.
THROUGH AN EYEPIECE
] 150 MM TELESCOPE · 25 MM EYEPIECEBright enough to pick out with your eyes alone, and from a lit street as well as a dark one. Today it is 4.95″ across. It stops being a point of light at about 12×, and at 48× it is a small round disc.
- 48×
- 1.08
- 1.25
- 13.0
- 4.95
- SHOWS A DISC FROM
- 12×
- MAGNITUDE TODAY
- −1.96 · within reach
Computed for 2026-08-27 from the centre of the Earth, and from the mean radius the catalogue holds. A distance changes daily, so this width is a fact about that date and not about the body.
CATALOG DATA
] 12 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT IT IS MADE OF
What the object is in itself, rather than how it happens to look from here.
- Mean temperature
- 167
- Rotation period
- 58.65
- Moons
- 0
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- North pole (RA)
- 281.0103
- North pole (Dec)
- 61.4155
THE ORBIT
The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.
- Orbital period
- 87.97
- Eccentricity
- Inclination
- 7
- Longitude of ascending node
- 48.33
- Longitude of perihelion
- 77.46
- Mean longitude
- 252.25
- Element epoch
- 2451545.0000
ALSO KNOWN AS
] 1 DESIGNATIONS- Common name Mercury
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Mercury [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/mercury
@misc{spacecatalog_mercury,
author = {{SpaceCatalog}},
title = {{Mercury}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/mercury},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from SpaceCatalog curated data.}
}The values above were taken from SpaceCatalog curated data — CC-BY-4.0. Citing this page does not replace citing that catalogue.