Moon's Position Over Earth
(to update, reload page)
Courtesy: Fourmilab Switzerland

Unlike Earth, the Moon is a barren, lifeless world with no liquid water and barely an atmosphere!  (1.6.x)   (1.4.1)

Essentially, the same side of the Moon always faces us!    View from Earth:  (1.6.x)   (1.4.1)

Because the Moon is nearer than any other major celestial body, it can produce dramatic "shadow events" like this!  (1.6.x)   (1.4.1)

 
 

The Moon's surface area is a bit less than the area of Asia, Earth's largest continent, and a bit greater than the area of Africa, Earth's second largest continent!

 

ECLIPSES

Eclipses occur whenever the Moon or Earth moves into or through the other's shadow.  This does not happen every month, as  the lunar orbit is inclined to Earth's orbit.  So Earth, the Sun and the Moon produce eclipses only about  every 6 monthsCalendar

During  Solar Eclipses  the Moon moves "directly" be- tween Earth and the Sun, so the lunar shadow extends down onto Earth's surface.  Solar Eclipses can only:
      happen at New Moon,
      last a very short time,
      be seen from small areas.

Current Sun vs Moon Sizes has more eclipse insights.

WARNING!   It is never safe to look directly at a Solar Eclipse with the naked eye!  And looking at one, for even an instant, through a telescope or binoculars with- out adequate safeguards can cause permanent blindness!  NEVER DO IT!  To learn how to safely "observe" a Solar Eclipse, consult your local planetarium or observatory.

During  Lunar Eclipses  the Moon moves directly behind Earth relative to the Sun, moving either partially or en- tirely into Earth's shadow.  Lunar Eclipses:
      happen at Full Moon,
      can last for hours,
      can be seen from over
            half of our planet.

Main Types of Eclipses:

      Solar Lunar

How a Solar Eclipse Looks from Space:

from "Day" Side
from "Night" Side

How a Lunar Eclipse Looks:
from the Moon

  Eclipse Seasons

NASA Eclipse Data Website
NASA Eclipses
Wikipedia Eclipse page
UNL Eclipse Explorer

MOON LANDING SITES & SURFACE VIEWS

The links below open photos taken by Apollo astronauts in the 1960s and '70s, showing the various types of terrain encountered at  the Apollo landing sites.  The terrains chosen for successive mis- sions were increasingly more varied and more demanding.



Click to send Photon

Apollo 11    terrain quite
      flat   #2   #3   #4

Apollo 12    terrain fairly
      flat   #2  at Surveyor 

Apollo 14  Frau Maro high-
      lands, boulders   #2   #3

Apollo 15  rolling, hilly
      terrain   #2   #3   #4   #5

Apollo 16  hilly, furrowed
      terrain   #2   #3   #4

Apollo 17  hilly, rocky valley
      #2   #3   #4   Big Rock

Apollo 11 Landing Site in 3-D
Alt+Drag moves shadows.

 

MOON MISSION TRAVERSE MAPS

These maps and pages show many details, including the routes taken by the Apollo astronauts as they explored the surface of the Moon.  The Lunar Rovers were used from Apollo 15 onward and vastly extended the distances the astronauts could travel.  So the scales of the maps vary.

Apollo 11   Map 2   Map 3
Apollo 12  (2 EVAs)   Map 2
Apollo 14   Map 2   Map 3
      Map 4
Apollo 15   Map 2    Map 3
Apollo 16   Map 2 
Apollo 17   Map 2    Map 3

Compare similar views of the traverse maps with the cool  History of Apollo Landings in 3-D.  Zoom, tilt and rotate the views, etc.  Awesome!

And here's an informative NASA graphic comparing the  Distances Traveled by Moon and Mars Rovers. 

Nice  Moon Mission Poster.

MOON ACTIVITIES

MAP THE MOON
BY EYE

Here's a rewarding activity.  First download and print out the  NASA/JPL Moon Journal Worksheet  .  Then take a pencil and your worksheet out with you on succeeding nights and map the Moon: its phases, its surface features.  Then, when the Moon is nearly Full, on the back of your worksheet sketch how it appears in a larger scale.  Do it again a month later and compare your drawings.  Were you able to draw a pretty good likeness of the Moon's dark areas, the maria (seas)?

Remember: it was only with the naked eye that any sky object could be observed un- til the invention of the tele- scope in the early 1600's!


MAP THE MOON
WITH BINOCULARS

Now, try mapping the Moon as you did above, this time with a pair of binoculars.  Even a cheap pair will reveal much more detail.  Compare your new maps with those you made when you mapped the Moon by eye alone.

Remember: until the advent of photography astronomers had to rely on the maps they drew by hand!  Just like the maps you sketched above!  So you're in good company.


MAKE A PAPER MODEL OF THE MOON!

CANON has a terrific website that offers free downloads of paper models, including this cool  3-D model of the Moon.  The labeled globe will quickly acquaint you with the Moon's most prominent features and many great Moon facts!


MAKE A YARDSTICK SCALE MODEL OF THE EARTH-MOON SYSTEM

Ask your parents or a teacher to help you find a 1" diameter button (blue if possible), a #2 pencil with an eraser they'll permit you to break off, a few pieces of transparent tape, and a yardstick they'll permit you to write on.

Making your model is simple. 1.) Tape the button so its cen- ter overlaps the left edge of the yardstick.  2.) Tape the eraser so its center is 30 1/8" from the left edge of the yard- stick, and label it "Average Moon Distance".  3.) Label the button "Earth".  4.) Now, 27 7/8" inches from the but- ton's center, draw a vertical line and label it "Minimum Perigee".  5.) And to finish,
31 7/8" from the button's cen- ter, draw a vertical line and label it "Maximum Apogee".

You now have a surprisingly accurate scale model of the Earth-Moon System!  More- over, you can easily take it anywhere!  If permitted, you might even want to paint the yardstick black and add con- tinents to Earth and maria to the Moon!

Want to get even fancier?  Use this  view of the Earth-Moon system  to add more details: the distance of Earth's geosynchronous satellites, and the average locations of 1) the Earth-Moon Barycenter, and 2) the Earth-Moon L1 Lagrange point!


VERIFY THAT THE MOON RISES ABOUT 50 MIN- UTES LATER EACH DAY

As you go about your obser- vations, it will be easy for you to verify that the Moon rises about 50 minutes later each day.  Of course, this is an average.  The actual time depends on your latitude and on the Moon's very irregular orbit.


VERIFY HOW EARTH'S TIDES ARE LINKED
TO THE MOON

Even the ancients knew that Earth's tides were influenced by the Moon.  If you live near the coastline of an ocean or other large body of water, make observations of your own.  Record how the water level differs when the Moon is rising, setting, high in the sky or hidden by Earth.  You can also check it at different times of the year against the graph to the right and to this  Perigee and Apogee List.


VERIFY THE
MOON'S PHASES

Here's an exercise that's fun to perform with friends and other sky enthusiasts.  For a few evenings each week, for two or three weeks, observe the Moon and compare its phase to the ones predicted  here  or on other websites.

In fact, updated for 2024, you can  Make a Moon Phases Calendar and Calculator  to help you!  It's awesome!


MEASURE THE NEXT SUPERMOON

Here's a cool group activity that you can suggest to your science teachers.  NASA and JPL guide you through the fine points of  Measuring a Supermoon!


VERIFY HOW THE MOON'S RISE & SET TIMES ARE RELATED
TO ITS PHASES

Just to the right in the center column of this page, you will see a list of the 8 major types of Moon phases.  Hover over them to find when the Moon should rise and set for each phase.  Then, with the Moon Phase Calendar you created above, find when the Moon will exhibit each of its major phases in the coming month.  On the day of each, confirm that the Moon does indeed rise and set when it should for each phase.


MORE PAPER MODELS: APOLLO PROGRAM!

The same CANON website offers these free Apollo-era paper models:
   Command-Service Module
   Lunar Module
   Lunar Roving Vehicle
   Lunar Surface Diorama
   NASA Spacesuits
   Saturn V Rocket
Make them all!


MAKE A PAPER MODEL OF NASA'S NEW ORION SPACECRAFT

NASA's new spacecraft will take us back to the Moon and beyond:  3-D paper model of Orion.  Be the first in your neighborhood to have this model of the future!


WHIP UP A MOON-
LIKE CRATER

Here's another group activity that you can suggest to your science teachers.  NASA and JPL give you the recipe for  making miniature Moon craters in the classroom!  Great educational fun!


SIMULATE A CONVER-
SATION BETWEEN YOUR EARTH-BOUND SELF AND
A FRIEND ON THE MOON

Use the Earth-Moon Distance diagram 2/3 of the way up the page for this.  Have a conver- sation with a friend, as if he or she is on the Moon!  As in- dicated to the diagram's left, click to send photons to the Moon and back for the time delay between exchanges.

For your Earth-Moon conver- sation to be accurate, you must wait for each photon to depart Earth "and" return from the Moon before you each answer one another!  Of course, counting "one-one thousand, two-two thousand, three three-thousand" in be- tween your exchanges with your friend works too.

For even more fun, try it with you and your friend facing away from each other or with a partition between you.  Do you think you could get used to phoning a friend on the Moon like this?

The Apollo astronauts and Mission Control had to deal with precisely this time delay whenever crews were on the Moon or in orbit around it!

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.

  • After you run the links at top that display planetary orbits, Right Drag with your mouse a to get a good sense of their 3-dimensional aspects.
  • If CELESTIA's clock (i.e. the program's date and time) is not visible at the top-right of its window, press the V key until you see it.  This will also turn on information text in other corners to help you keep track of several as- pects of the event you're viewing.  Keeping an eye on CELESTIA's clock at the top-right will help you appreciate how much time is passing in each view.
  • Pressing the "un-shifted" L key and K key respectively will speed up and slow down CELESTIA's flow of time by a factor of 10 in version 1.6.x and 1.4.1.
  • Pressing Shift+L and Shift+K respectively will speed up and slow down CELESTIA's flow of time by a factor of 2 in version 1.6.x only.
  • Pressing the J key (either shifted or "un-shifted") will reverse CELESTIA's flow of time in version 1.6.x and 1.4.1.

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


THE MOON

View Moon in 3D      3-D in Orbit (from Sun's direction)
Moon Trek:  for 3D Moon, at lower left of Trek window
      select globe (Projections), then 3D Globe.
Current:
      Orbital Position, Phase & Distance
      Viewed from Earth: Appar. Size, Phase & Distance
      Earth & Moon Viewed from Sun   Interactive
      Location in the Constellations
Your  Moonrise, Moonset, Sunrise & Sunset  today.

Physical Properties:
      Equatorial Size:    Compare   Compare in 3-D
            Radius:    1,738.1 km
            Diameter:    3,476.2 km
            Diameter (Earth = 1):    0.2725
            View  How Big Is Our Moon?  video.
            Compare to Other Moons


COMPARE MOON TO EARTH'S CONTINENTS

      Rotational Flattening:    0.0012
      Mass (Earth = 1):    0.0123
      Volume (Earth = 1):    0.0203
      Mean Density (Water = 1):    3.34
      Mean Density (Earth = 1):    0.607
      Surface Gravity (Earth = 1):    0.165
      Surface Temperatures:  average  -23°C  (-9°F)  
      Inclination of Axis to Orbit:    6.68°
      Rotation and Revolution Period: (tidally "locked", so
            the same side of Moon always faces Earth)
            Synodic (in Earth days):    29.53 (cycle of Phases)
            Sidereal (in Earth days):    27.3217
            Note: Earth Day Lengths
                  Mean Solar:  24.0000 hours (24h00m00s)
                  Sidereal:  23.9345 hr (23h56m4.1s)
      Albedo (geometric):    0.12
      Magnetic Field (Earth = 1):    extremely weak

More Views of Moon in 3-D:
      NASA's Overview of the Moon
      NASA's Moon Portal  is similar but opens a few
            different stories and interactive features.
      History of Apollo Landings in 3-D  zoom way in!
      Moon-Viz  gives you an appreciation for how many
            satellites have studied and will study the Moon.
NASA's Moon to Mars
ESA's Lunar Exploration pages

Moon Surface:
      LROC Quickmap
      Moon Trek (Maps)

      View the Moon's Features  that are visible from Earth
          with binoculars or a low-power telescope.
      Moon-scapes in 3-D:
            Apollo 11    Tsiolkovskiy Crater    Petavius Crater
            Copernicus Crater    Hertzsprung Crater


THE MOON'S SLOW MONTH-LONG ROTATION
(from above                   lunar N Pole)


      Download Moon maps to aid your viewing:
            USAF Lunar Earthside Map (high-res)
            NASA Apollo-Era Lunar Charts:
                  Polar and Equatorial (small)
            Moon Landing Sites

Moon Internal Structure:
      NASA Graphic
      Compared to Earth & Mars 
      Compared to Inner Planets 

How the Moon Formed poster

Spacecraft in 3-D:
      Orion:  #1    #2   #3   #4   #5
      Altair Lunar Lander 
      Chang'e 3    Yutu (rover) 
      Apollo:
            Command & Service Modules:  #1   #2   #3   #4
                  Interior:  #1   #2    Combined (awesome):  #1
            Lunar Excursion Module:   #1   #2   #3   #4   #5
      Luna 9    Lunokhod-2 

Moon Orbit:
      Current Lunar Orbit View from the Sun   Interactive
      Orbit highly variable: note amount and direction the
           Moon strays from initial path.  (1.6.x)   (1.4.1)
      Wikipedia's Orbit of the Moon page

MOON DISTANCE: General Details

      Distance:  (Earth diameters are "equatorial")
            Mean:    384,400 km  (30.13 Earth dia.)
            Perigee:
                  Mean:    363,300 km
                  Min:    356,400 km  (27.9 Earth dia.)
            Apogee:
                  Mean:    405,500 km
                  Max:    406,700 km  (31.9 Earth dia.)
            Perigee and Apogee List

      Velocity: (around Earth)
            Mean:    3,680 km/hr
                          (about as fast
                          as an SR-71)
            Min:    3,480 km/hr
            Max:    3,950 km/hr

      View Earth-Moon Barycenter video
     
      View Moon's Orbital Position & Phase video


The lunar orbit would
easily fit inside the Sun!

The Moon's path around the Sun is
often shown incorrectly with loops or
zig-zags!  Actually it is nearly a circle—
always concave relative to the Sun!

EARTH'S & THE MOON'S PATHS AROUND THE SUN

Scroll image above for the actual shape of the Moon's path around
the Sun.  Click on image to open it fully in a separate window.

      Lunar Orbit Periods:  (Months)
            Sidereal:   27.32166 days (relative to background)
            Synodic:   29.53059 days (relative to Sun, Phases)
            Tropical:   27.32158 days (relative to equinoxes)
            Anomalistic:   27.55455 (relative to perigees)
            Draconic:   27.21222 (relative to nodes)

THE MOON'S COMPLEX ORBIT AROUND EARTH

The Moon's orbit changes in complex
ways.  Its plane and line of Nodes rotate "backwards" about every 18½ years!  Its
line between perigee and apogee ro-
tates "forward" almost every 9 years!

And don't forget: every month
Earth and the Moon also revolve
once around their  barycenter!

      Long-Term Orbital Periods:
            Precession of Apsides:   8.8504 years
            Precession of Nodes:   18.5996 years (retrograde)
      Spin-Orbit Resonance:     Yes, 1 to 1
            (so the same side of Moon always faces Earth)
      Eccentricity:
            Mean:   0.0549
            Min:   0.0255
            Max:   0.0775
      Inclination to Ecliptic:    5.145°

 MOON'S SIZE VARIATION SEEN FROM EARTH
A "supermoon" occurs when the Moon is full
and in the closest 10% of its distance range.

Current Apparent Moon Size vs Sun Size

Supermoons:
      Brightness:
            Area Component:  up to 15% greater than avg
            Distance Component:  up to 15% greater than avg
      Cycle:
            Pairs or Triples about every 13½ calendar months

Supermoons & Extreme Perigean Tides:  2020-2022

Moon Phases:    
      Current:
            Orbital Position & Phase
                  View with  Moon Phaser  interactive tool
            Distance, Apparent Size and Phase from Earth
            Location in the Constellations
      Study Phases with these interactives:   #1   #2   #3
      Lunar Phase Simulator
      2024 Best Moon-Planet Conjunctions

MOON PHASES 2024
video credit: NASA's Scientific Visualization Studio

1.     New MoonsNew Moons essentially rise and set with the Sun and reflect no sunlight toward Earth.  So they do not impede Deep Sky Observing all night.

2.     Waxing Crescent MoonsWaxing Crescent Moons generally
rise between sunrise and "local
noon".  Setting between sunset
and "local midnight", they are up
and impede Deep Sky Observing
early in the evening.

3.     1st Qtr Moons1st Qtr Moons generally rise near "local noon".  Setting near "local midnight", they are up and impede Deep Sky Observing for the first
half of the night.

4.     Waxing Gibbous MoonsWaxing Gibbous Moons generally
rise between "local noon" and sun-
set.  Setting between "local midnight"
and sunrise, they are up and
impede Deep Sky Observing from
sunset through the early morning.

5.     Full MoonsFull Moons generally rise near
sunset, then set near sunrise.  So
they are up and impede Deep Sky Observing all night long.

6.     Waning Gibbous MoonsWaning Gibbous Moons generally
rise between sunset and "local
midnight".  Setting between sunrise and "local noon", they are up and impede Deep Sky Observing in the
late evening through sunrise.

7.     Last Qtr MoonsLast Qtr Moons generally rise near "local midnight" and set near "local noon", allowing Deep Sky Observing only during the first half of the night.

8.     Waning Crescent MoonsWaning Crescent Moons generally
rise between "local midnight" and
sunrise.  Setting between "local
noon" and sunset, they are up and
impede Deep Sky Observing only during the early morning.

 

QUICK VIEW OF 2024

MOON PHASES & ECLIPSES (UTC)

SOLAR: Total = T, Annular = A    LUNAR: Partial = P, Penumbral = Pn

Click on months for Phases

      2024 Phase List  plus more Astronomical Events

Old Format Previous Months' Phase Calendars:
2014:  Jan      2013:  Dec    Nov    Oct    Sep    Aug    Jul                              Jun    May    Apr    Mar    Feb   

  ECLIPSE "SEASONS" 2019 - 2030


AWESOME TOTAL SOLAR ECLIPSE:
2024 April 8      Maps      Videos

SOLAR ECLIPSE QUICK REFERENCE MAPS
2001-2020      2021-2040      2041-2060

KEEP SAFE!     It is never safe to look directly at
the Sun with the naked eye!  Moreover, looking at it—even for an instant—through either a telescope or binoculars without adequate safeguards can cause permanent blindness!  NEVER DO IT!  To learn how to safely "observe" the Sun and a Solar Eclipse, consult your local planetarium or observatory.

     NASA's 5 Millenia of Eclipses:  Solar  Lunar

View of Moon (from Sun's direction in CELESTIA):
      With Location Labels ON:  (1.6.x)   (1.4.1)
      With Location Labels OFF:  (1.6.x)   (1.4.1)

Partial Information Source: NASA Fact Sheets


ADJECTIVES MEANING
"pertaining to the Moon"

      lunar (from Latin: Luna)
      selenian (from Greek goddess, Selene)


THE MOON'S MOTION THROUGH OUR SKY

Like the Sun, every day the Moon generally rises in the east, moves westward across the sky, then sets in the west.  Also like the Sun, the Moon has an "apparent" motion independent of the daily-rotating background of fixed stars.  This independent motion was much more obvious to the ancients than the Sun's motion, for the Moon moves through the background stars much faster —on average about 13⅓ times faster—than the Sun!  Always staying within the band of the Zodiac, the Moon moves generally eastward through the background stars, each hour moving a distance roughly equal to its own diameter.  The SkyMarvels™ video directly below shows the Moon's motion for the full year of 2014.


On average, this motion makes the Moon visible in the sky for about 12½ hours each day, not 12, because the Earth has to rotate a little further to "catch up" with the moving Moon!  On average the Moon also therefore rises and sets about 50 minutes later each day, completing one circuit of the heavens in about 27⅓ days relative to the stars and in about 29½ days relative to the Sun.  These two periods are known respectively as a sidereal month and a synodic month, and they are only averages due to the  Moon's quite-irregular orbit.


HISTORY FEATURES:

For the 50th anniversary of human- kind's first walk on another world, check out these awesome interac- tive adventures:  First Men on the Moon,   Apollo 11 in Real-Time  and  Mapping the Mission.  Then view the  Command Module in 3-Dits interior  and the  LEM on the Moon in 3-D!  Sadly, the awesome "We Choose the Moon", an excellent recre- ation written in Flash, can no longer be found on the net.  Truly a great loss.

BEST ECLIPSE IN U.S. HISTORY!

That's how the Total Solar Eclipse of 21 August 2017 was described.  That Monday the Moon's shadow whisked across the United States, gracing it with a true sky marvel!   Here are some excellent videos of it!
NASA Page   PDF 

Awesome  online app  and animations from NASA:

Path    Visibility         Eclipse Cone

Path on Rectangular World Day-Night Map

A Fun Math Workout

Why Eclipses Occur    Oblique View   


MORE GREAT MOON LINKS

APOLLO Missions:  high resolution posters

     ONE SMALL STEP: Apollo 11
     APOLLO Manned Lunar Landing Mission Profile
     DESTINATION MOON

ARTEMIS I Moon Mission Poster

Here's a link to a nice NASA page:  Timeline of Lunar Exploration Missions.  Lots of good background info here!

Here's a link to a nice  Lunar Panorama from Apollo 17  in color.  Yes, that's a barren-looking place!  Can you find the Rover?

SAME SIDE OF THE MOON
ALWAYS FACES EARTH

TOUR OF THE MOON
video credit: NASA/Goddard Space Flight Center

EVOLUTION OF THE MOON
video credit: NASA/Goddard Space Flight Center

LUNAR CRATERS
video credit: NASA/Goddard Space Flight Center

MORE GREAT MOON VIDEOS

Apollo Landing Sites  shows Moon phases during missions.

LRO Takes the Moon's Temperature

Lunar Clementine Moon SpinVideo Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

Clementine Lunar South PoleVideo Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

Lunar Prospector Hydrogen Concentration - South PoleVideo Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

Apollo Mission Lunar Surface Footage.   Video Credit: NASA/Johnson Space Center




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"Our Moon is the greatest influence on Earth's tides."

Earth's & our Moon's motion around their barycenter helps produce Earth's tides.

Current Moon   
     Location in the Constell.
     Moon Phaser


(to update, reload page)

Current Apparent Sizes
(geocentric)

K E E P  S A F E!   It is never NEVER safe to
look directly at the real Sun with the naked
eye!  Moreover, looking at it—even for an instant—
through a telescope, binoculars, camera or similar
instrument without adequate safeguards can cause
permanent blindness!  NEVER DO IT!  To learn how
you can safely "observe" the Sun, consult the pro-
fessionals at your local planetarium or observatory.


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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

UPCOMING:

Eclipses
     *Total Solar:  Apr 8   

Moon-Planet Conjunctions

Lunar Occultations:  IOTA

      Planets   Bright Stars

Extreme Perigean Tides

NOAA Tides & Currents  Map

MOON INTERACTIVES

QUICK ACCESS LIST

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

NASA's Moon Overview  (in cool interactive 3-D!)

Your  Moonrise, Moonset, Sunrise & Sunset  today.

Soar above the Moon with awesome  LROC QuickMap

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

Study Moon Phases w/ these interactives:   #1   #2   #3

More Lunar Phase Sims:
#1   #2   Moon Phaser

History of Apollo Landings

First Men on the Moon

Apollo 11 in Real-Time

Mapping the Mission

Apollo 17 in Real-Time

AstroMaterials 3D Lunar

NASA's  Moon Trek  mapping application

Google Moon

Study the Moon's surface with NASA's  Lunar Recon- naissance Orbiter Camera

Note: We Choose the Moon,
a terrific Flash app, is no longer on net.  A great loss.

And don't forget to look over directly to the left column for a few more cool interactives!


MOON FUN FACTS

The Moon is moving away from Earth by about 4 centi- meters (about 1½ inches) per year!  So the length of lunar months is increasing!

 

On average, the Moon's re- flectivity is about that of a well-worn asphalt road.

The Moon moves in its orbit at an average speed of about 3,600 kmh (2300 mph)! That's roughly the maximum speed of the SR-71, the fastest jet plane ever flown by man!

And yet, most persons can run faster than the Moon ro- tates at its equator!

Essentially the same side of the Moon always faces us here on Earth  because, over eons, gravitational forces have synchronized the lunar spin and orbit!

The "dark side of the Moon" is an often mis-used term,
for the Moon's dark half is constantly changing due to the lunar rotation!  So the "dark side of the Moon" (or part of it) can actually be seen from Earth most of the time!  Often the term "dark side of the Moon" is used incorrectly when what is actually meant is the "far side of the Moon."

With few maria, the Moon's  far side  looks very different from the  side facing Earth.

The lunar core is believed to be quite small and  not quite at the center of the Moon!

Like immense brake shoes, the tides are slowing Earth's spin!  At the same time this "synchronizing effect" also causes the lunar orbit to slow and the Moon to gradually re- cede from Earth—at a rate of a few centimeters per year!  So, far in the future, the same side of Earth will always face the Moon, and a day and a month will be equal in length—about fifty Earth days long!

Seen from Earth, the Moon's phase is shown above (near top) at "Current Moon". Seen from the Moon, our "Earth's" phase is shown (at upper
left) as the "Moon's Position Over Earth".  These phases are always complements of each other! 

WHAT CAUSES MOON PHASES

Study Moon Phases w/ these interactives:   #1   #2   #3

Lunar Phase Simulator

NOAA's Astronomical Data page

Wikipedia's Lunar Phases page

2024 Phase List

MOON MISC.

TIDES

Tides  are our planet's peri- odic variations in water level, produced by the gravitational pull of the Sun and the Moon, and the "centrifugal effect"
(actually a manifestation of "inertia") generated by the Moon's and Earth's motion around their barycenter.

Because the Moon orbits in the direction of Earth's spin, our planet must spin more than 24 hours (50 minutes more) for a point "under the Moon" one day to "return there" the next.  Thus, for "ideal" tides, about 12 hr 25 min elapses from one high tide to the next, or one low tide to the next.

The following sites provide details on tides: their types, causes, frequencies, etc.

NASA Science: Tides pages

NOAA Tides pages

NOAA What are Spring & Neap Tides? 

NOAA What is a Perigean Spring Tide? 

NOAA SciJinks Tides pages

Wikipedia Tide pages

NOAA Tides & Currents  Map

And from EarthSpaceLab, its awesome  Tidal Phenomena  lets you study tides in 3-D!

And don't forget—you can learn more with our  Earth's Tides Poster, which is always available as a  Sky-Gift.


LUNAR APOGEES & PERIGEES

Lunar apogees & perigees show just  how irregular the lunar orbit is.  From 1500 to 2500 CE, the Moon's apogees average roughly 405,400 km, varying from about 404,050 km to an extreme maximum of about 406,720 km.  Lunar perigees however, as can be seen in the graph just to the left, are a bit more variable.  Averaging about 363,400 km, they can vary from roughly 370,350 km to an extreme minimum of about 356,370 km!  This means that, while the Moon's apogees vary by less than 2,700 km, its peri- gees vary by over five times as much—almost 14,000 km!

Charting lunar perigees is particularly important in tide prediction.  Tides that occur close to the times of a lunar perigee (Perigean Tides) can be substantially higher than average and produce signif- ican shore erosion.  This is especially true if they occur near Full or New Moons, at which times the gravities of the Sun and Moon's pull on our planet essentially along the same axis. This results in  Perigean Spring Tides  , and these are stronger still.  They recur about every 6½
to 7 months, thus returning
a little later on our calendar each year.

It is worth noting that the most extreme lunar apogees and perigees tend to happen in the winter months of the Northern Hemisphere.  This is when Earth is nearest its perihelion, i.e. closest (yes, closest!) to the Sun.  Extreme apogees tend to happen when the Moon is New, since the Sun pulls it "away from" Earth.  Extreme perigees in contrast tend to occur when the Moon is Full, as the Sun pulls it "toward" Earth.


SKYMARVELS™
ADD-ONS FOR CELESTIA FEATURING THE MOON

Solar
Eclipse Finder

Lunar
Eclipse Finder


SKYMARVELS™
POSTERS FEATURING THE MOON

Earth's Tides

Our Corner of the Cosmos


SKYMARVELS™
VIDEOS FEATURING THE MOON

Perseid Meteor Shower 2010

Geminid Meteor Shower 2010

Geminid Meteor Shower 2012

Perseid Meteor Shower 2013

 

The Speed of Light

Stunning Fields of View 001

Stunning Fields of View 002

Have You Ever . . . ?

"celestia4all" Site Preview


Solar Eclipses:

   Solar Eclipses thru 2012

   Solar Eclipse 2010 Jul 11

   Solar Eclipse 2012 Nov 13

   Solar Eclipse 2013 Nov 3


Lunar Eclipses:

   Lunar Eclipses thru 2012

   Lunar Eclipse 2010 Jun 26

   Lunar Eclipse 2010 Dec 21

   Lunar Eclipse 2011 Jun 15

 

Moon's Occultation of Venus 2010 May 16

Moon's Occultation of Venus 2010 Sep 11

 

Moon 2013

How Big Is Our Moon?

The Same Side of the Moon Always Faces Earth

The Earth-Moon Barycenter

Phases of the Moon

Moon Phases Calendar