Mercury is a barren world, which resembles Earth's Moon in many ways.  (1.6.x)   (1.4.1)

Mercury's spin (rotation) and orbit are "in synch"! So part of the planet experiences double sunrises!  (1.6.x)   (1.4.1)

Mercury is the closest planet to the Sun, so it moves in its orbit faster than any other major planet!  (1.6.x)   (1.4.1)

 
 

 
 
 
 

SURFACE VIEWS

Although no spacecraft has yet visited the surface of the innermost planet, much has been learned about it.  Here are links to science-based representations of Mercury's Sun-baked surface, which has often been likened to the surface of the Moon.

Barren Mercury: © SkyMarvels

Hostile Mercury: © SkyMarvels

MESSENGER Mission Site
NASA Solar System Sim

MERCURY ACTIVITIES

MAKE PAPER MODEL OF MERCURY MESSENGER SPACECRAFT

Simple    Advanced   


COMPARE MAPS OF MERCURY AND THE MOON

Though Mercury resembles the Moon at first glance, each world has its own character.  Use the QuickMaps below to gain a better understading of how Mercury and the Moon are alike and different:

Globes:     Mercury    Moon

Maps:        Mercury    Moon

Does Mercury have any large maria on it?  On closer exam- ination these 2 worlds, which at first glance appear so sim- lar, are really quite different!

MERCURY'S
CURIOUS ORBIT

Among the orbits of the eight major planets, Mercury's can be said to be the "orbit of superlatives".  It is inclined to the Ecliptic more than any other orbit of a major planet, and it also has the highest eccentricity!  Moreover, as we have already seen, the fleet planet's orbit and spin are synchronized more than those of any other major planet!

Mercury's orbit may be the most intriguing in the Solar System for another reason!  As seen a bit below in the center column, the orbit of Mercury "rotates" around the Sun!  This phenomenon is called the "Precession of Perihelion", and the orbits of all celestial bodies exhibit a similar motion, though to a significantly lesser degree. Even in Mercury's case, its rate is extremely slow—only about 1/6 of a degree each century.  This means that it takes over 200,000 years for Mercury's "orbit" to rotate once around the Sun!  Even so, that is still faster than could be accounted for by Newton's Law of Gravitation.

It was not until Einstein's General Theory of Relativity that the rate of Mercury's Precession of Perihelion could be explained. 

CELES-TIPS

The following will help you enjoy this page's 1.6.x and 1.4.1 links that run events directly in CELESTIA.  If you're new to the program, these tips will also help you learn to use it.

Are you unfamiliar with our 1.6.x and 1.4.1 links?  For an explanation  click here.

You'll find more information about many of CELESTIA's controls on our  Learning Center  page.


MERCURY

View Mercury in 3-D   Another   Another     3-D in Orbit
      QuickMap 3-D Globe w/Labels    Mercury Trek
Current Views and Conditions from Earth
Current Location in the Constel.   Skypath 2024
Current Location in Orbit
Current Year's Greatest Elongations   List


Viewed from the Sun, Mercury exhibits a peculiar motion.  Its spin & elliptical orbit are synchronized,
so it appears to stop rotating every time it reaches perihelion!

Next Transit:   2032 Nov 13 
Physical Properties:
      Equatorial Size:    Compare in 3-D
            Radius:    2,440 km
            Diameter:    4,880 km
            Diameter (Earth = 1):    0.383
      Rotational Flattening:    0
      Mass (Earth = 1):    0.055
      Volume (Earth = 1):    0.056
      Mean Density (Water = 1):    5.43
      Mean Density (Earth = 1):    0.984
      Surface Gravity (Earth = 1):    0.378
      Surface Temperatures:  average  167°C  (332°F)  
      Axial Tilt:    0.0° 
            Where Poles Point 
      Rotation Period:
            Synodic ("Day" in Earth solar* days):    175.942
            Sidereal (Earth solar* days):    58.65
            Note: Earth Day Lengths
                 Mean Solar:  24.0000 hours (24h00m00s)
                 Sidereal:  23.9345 hr (23h56m4.1s)
      Albedo (geometric):    0.14
      Magnetic Field (Earth = 1):    0.017
            NASA Messenger Site Graphic  
            NASA/JPL PhotoJournal Site Graphic  

NASA's Overview of Mercury
NASA Mercury In Depth page
MESSENGER Mission Site
NASA Space Place: All About Mercury

COMPARE MERCURY TO EARTH'S CONTINENTS

Mercury Surface:
      Global Views (greyscale):
            North Pole    South Pole
            0° North, 0° East    0° North, 90° East
            0° North, 180° East    0° North, 270° East
      Images from Messenger:
            Highlights Collections
            Global Mosaics
            Featured Image Database
      Study Mercury's Surface with QuickMap
      Map of Mercury's Surface ("enhanced color"):
            Global Mosaic Map  (3.74 km per pixel)
            NASA explanation of "enhanced color" map
      NASA / JPL's Photojournal pages for Mercury
      Rachmaninoff Crater 3-D Rotation 
      NASA Mercury Enhanced-Color Rotation Vid

Mercury Atmosphere:   tenuous
      Surface Pressure (Earth = 1):   10‒14
      Origin:   Solar Wind, Planet's Crust, Meteoroids
      Wikipedia page

Mercury Structure:
      Compared to Other Inner Planets  
      A Mystery Solved

Spacecraft:
      BepiColombo in 3-D (Attitude Viewer)  rotate & zoom
            ESA Mission Sites: #1   #2
            Wikipedia page
            3-D Interactive Trajectory  scroll, zoom, drag, play
      Mercury Messenger:
            Mission Sites:   JHUAPL   NASA
            Wikipedia page
            3-D Models (shapes only):   #1   #2

Number of Moons:    0
Ring System:    No

Planet Classifications:
      Inner Planet  (along with Venus, Earth & Mars)
      Terrestrial Planet  (primarily Earth-like structure)
      Inferior Planet  (has smaller orbit than Earth and
            exhibits a full range of phases)
            Current Phase of Mercury
            Phases of the Inner Planets Video
            Phases of Mercury Sim  (in Orbit Sizes box
                  select Mercury as target)
            Configurations Sim  (in Orbit Sizes box
                  select Earth and Mercury)
            No. of Greatest Elongations per Yr:  6 or 7  

Mercury Orbit:   (1.6.x)   (1.4.1)
      Period:    87.969 Earth solar days
      Distance from Sun:
            Mean (Earth = 1 AU):    0.387 AU
            Mean:    57,910,000 km
            Perihelion:    46,000,000 km   (0.307 AU)
            Aphelion:    69,820,000 km   (0.467 AU)
      Velocity:
            Mean:    172,332 km/hr
            Min:    139,896 km/hr
            Max:    212,328 km/hr
      Eccentricity:    0.206
      Inclination to Ecliptic:    7.00°
      Spin-Orbit Resonance:    Yes, 3 to 2
            (verify Mercury's 3 rotations in each 2 orbits)
            this produces Mecury's  "double sunrises" 
      Precession of Perihelion:    574 arc-sec / century 

MERCURY'S SPIN-ORBIT RESONANCE
AND PRECESSION OF PERIHELION

Mercury's elliptical orbit itself actually rotates very
slowly around the Sun!  Its perihelion "precesses"
a full 360° once roughly every 225,000 years!

(Note: Eccentricity and speed of Precession
            are greatly exaggerated for emphasis.)

E = mc2

The precession of Mercury's perihelion stands as
one of the enduring proofs of General Relativity.


     When Mercury's Orbit Appears "Edge-On" from Earth
     Transits (in front of the Sun):
            Frequency:    approx 13 per century
            7-Century Catalog
            Why All Currently Occur in May or November
            Last 2 Transits:
                  2016 May 9   SDO Video 
                  2019 Nov 11    SDO Video 
            Next 2 Transits:   2032 Nov 13  ;  2039 Nov 7

            Wikipedia's Transit of Mercury page
            Properties of Mercury's Transits:
                  May Transits:
                        •  occur near Mercury's Descending Node
                        •  progress to the southwest
                        •  are less numerous than Nov transits
                        •  occur when Mercury looks larger
                  November Transits:
                        •  occur near Mercury's Ascending Node
                        •  progress to the northwest
                        •  are more numerous than May transits
                        •  occur when Mercury looks smaller
            NASA Video of the 2016 May 9 Transit 
            NASA Graphic of the 2006 Nov 8 Transit

Best Times to View Mercury:  when Greatest . . .
      Eastern Elongations occur betw. March & July
      Western Elongations occur betw. Sept. & Dec.

Partial Information Source: NASA Fact Sheets


ADJECTIVES MEANING
"pertaining to Mercury"

      Mercurian
      Hermian (from Greek god, Hermes)


MERCURY: Its Phases as an Inferior Planet

MERCURY'S & VENUS'S SKY PATHS 2013–2014

MERCURY
video credit: Science@NASA

MERCURY: Its Weird Solar Day over its South Pole
video credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

MESSENGER: Mercury Orbit Insertion
video credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


DIRECT LINKS TO MORE VIDEOS

From NASA's Photojournal pages, here's  A Tribute to MESSENGER  

From NASA's Photojournal pages, here's  Mercury: Getting the Spins  

From NASA's Photojournal pages, here's  A Bit of an Exaggeration  




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SKY VIEWING
SOLAR SYSTEM
THE SUN
MERCURY
VENUS
EARTH
THE MOON
MARS
JUPITER
SATURN
URANUS
NEPTUNE
SMALLER WORLDS
STELLAR OBJECTS
EXOPLANETS
DEEP-SKY OBJECTS
SCALE OF THE COSMOS
———————
SKY-FUN / SKY-GAMES

NASA's LATEST

MERCURY MESSENGER status (completed mission with impact on Mercury as planned on 2015 Apr 30)


ESA's LATEST

Where is BepiColombo?  cool interactive from ESA.

BepiColombo in 3-D (Attitude Viewer)  rotate and zoom


MERCURY FUN FACTS

Mercury's surface area
is close to the combined
areas of Asia and Africa!

Mercury, smallest of the eight major planets, is smaller than Jupiter's moon Ganymede & Saturn's moon Titan!

The precession of Mercury's perihelion stands as one of the great enduring proofs of Einstein's General Theory of Relativity!

Relative to its size, Mercury is the most metal-rich major planet!

Of all the other planets, it is Venus which has an orbit closest in size to that of Earth.  And yet, because of how the planets orbit the Sun,  the major planet that spends more time closer to Earth than any other turns out to be Mercury!  It's aver- age distance from Earth is quite a bit less than Venus's!

In fact, not only is Mercury the planet closest to the Sun, it is also the planet closest (on average) to each and every other major planet in our Solar System! 

Mercury exhibits phases like those of the Moon!  However, unlike the lunar phases, that appear to march across the Moon's surface from west to east (relative to our sky di- rections), Mercury's phases appear to us on Earth to pro- gress "backwards", that is, across its surface from east to west!

The durations of Mercury's phases are not as uniform as the Moon's phases!  Because it is an  Inferior Planet, for a good bit more than half of its orbit Mercury appears more than "half-illuminated" to us here on Earth!

Some locations on Mercury experience  double sunrises and sunsets!  Other locations experience days where  the Sun stops in the sky, eases backward, then goes forward again!  Mercury's spin-orbit resonance is responsible for this odd behavior.

Mercury's day is almost one half of an "Earth year" long!

Relative to its overall size, Mercury has a larger metallic core than any other planet!

Though the 8 major planets do not possess particularly elongated orbits,  Mercury's orbit  is the most elongated or elliptical of them.

Mercury is so near the Sun that it is difficult to observe.  Most often it is hidden in the Sun's glare.  So a relatively small percentage of persons has ever seen Mercury in the sky!  If you've seen it, you are one of the lucky ones!

Mercury's lack of moons is partly due to its nearness to the Sun!  The solar gravity makes it harder for Mercury to retain orbiting bodies.

MERCURY INTERACTIVES

QUICK ACCESS LIST

Note: some links are echoed elsewhere on this page and may include descriptive text.

View Mercury in 3-D  superb!
Another    Another 

Study Mercury's Surface with QuickMap

Links to interactive features that show Mercury's orbit in 3-D can be found on our  Solar System page

Where is BepiColombo?  cool interactive from ESA.

BepiColombo in 3-D (Attitude Viewer)  rotate and zoom

MESSENGER Games and Simulations  You'll have to ZOOM IN your new window to enjoy these, but it's worth it.  The best three are included below to make accessing them a little easier! 

Day on Mercury  How the Sun appears to halt in Mercury's sky!  Don't forget to zoom in.

Sun's Size in Earth's and Mercury's Skies  shows how Mercury's highly elliptical orbit makes the Sun appear notably larger at perihelion than at aphelion.  Don't forget to zoom in.

Mercury's Orbit & Rotation  shows its 3 to 2 spin-orbit resonance, also comparing Mercury's orbit and spin characteristics to Earth's.  Don't forget to zoom in.

Compare Mercury to "__" 3-D


SKYMARVELS™
VIDEOS FEATURING MERCURY

The Solar System Barycenter

Inferior Planet Phases

Stunning Fields of View 002

Have You Ever . . . ?

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