Sun's Over Above Earth

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

Day & Night on Earth
View Earth's Night Half
Sunrise & Sunset on Earth
No Sunlight on Entire Earth
Six Current Views of Earth

"PLANET OF LIFE!"

Earth, the cradle of humankind, is a watery world and the only planet on which we know life exists!  (1.6.x)   (1.4.1)

Earth is the third planet from the Sun, and the one against which all other planets are measured!  (1.6.x)   (1.4.1)

Right Drag with your mouse after you run the links above that display the planetary orbits to get a good sense of their 3-dimensional aspects.

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

EARTH ACTIVITIES

MAKE YOUR OWN COMPASS

From the National Oceanic & Atmospheric Admin. (NOAA), here's an activity that's fun!  And potentially useful too!  Make Your own Compass.  Moreover, when you use the compass you make, you'll be confirming that Earth has a magnetic field!


VERIFY HOW GRAVITY WORKS

For thousands of years even the smartest people in the world accepted that heavier objects always fell to Earth faster than lighter objects.  After you do the following simple little experiment, you will surely wonder why they never did something similar themselves!  And you'll be smarter than them (well— about gravity anyway.)

Drop a quarter and a dime at the same time.  Does one fall faster than the other?  Does it make any difference if you drop them at the same time from a different height?  To be sure of your answer, go ahead and repeat this quick experiment several times.  It won't take you long to know more about gravity than the ancient "experts" did!

EARTH'S SEASONS

WHY EARTH HAS SEASONS.

From UNL here's a fantastic Flash interactive that lets you study what produces  Earth's Seasons  during our yearly journey around the Sun!

SEE EARTH'S SNOW & ICE COVER VARY WITH THE SEASONS


CLIMATIC VS. ASTRONOMICAL SEASONS

Most school children know that the climatic seasons of the Northern and Southern Hemispheres are the reverse of each other's.  For example, climatically-speaking, when it is Summer in the Northern Hemisphere, it is Winter in the Southern Hemisphere.

However, the "astronomical" seasons, as well as their respective equinoxes and solstices, have traditionally always been named for the "climatic" seasons of the Northern Hemisphere, (no doubt because roughly 90% of Earth's population lives there.)  Thus, the Summer Solstice, for instance, is the solstice in June that marks the start of the Northern Hemisphere's summer.

Unfortunately this traditional naming convention creates an ambiguity.  It means that astronomers in the Southern Hemisphere experience the traditional Summer Solstice at the start of their "climatic" Winter!

This is why we increasingly see the less traditional (and slightly less recognizable) terms: March Equinox, June Solstice, September Equinox and December Solstice.  As these terms eliminate the traqditional ambiguity, they are becoming accepted as the best ways to refer to the equinoxes and solstices.


HOW LONG IS EACH SEASON?

Since their beginnings and ends are strictly defined by the arrival of the Sun at the equinoxes and the solstices in our sky, our astronomical seasons have durations of specific lengths.  Although many people believe that the lengths of the astronomical seasons are the same, this proves not to be the case.  This is because, while the equinoxes and solstices are spaced at equal intervals of 90° around the Celestial Sphere, Earth's changing velocity in its elliptical orbit causes the Sun to appear to arrive a little early at parts of the sky, and a little late at others.  Summer therefore becomes the longest of the "astronomical" seasons and Winter the shortest.

Lengths of the "Astronomical" Seasons

Spring: 92 3/4 days
Summer: 93 2/3 days
Autumn: 89 5/6 days
Winter: 89 days.

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.

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


adapted from NASA GSFC SVS animation
Earth's Snow and Ice Cover by Month    View Larger

Don't forget to also check out our  Earth Weather  page.

EARTH

Current Distances and Views from the Sun and Moon
Current Location in Orbit

Equatorial Radius:    6,378.1 km
Polar Radius:    6,356.8 km
Rotational Flattening:    0.00335
Mass:    5.9736 trillion trillion tons
Volume:    1.08321 trillion cubic kilometers
Mean Density (Water = 1):    5.52
Surface Gravity (standard):    9.81 m/s2

Inclination of Axis to Orbit:    23.45°   (1.6.x)
      Variation:    22.1° to 24.5° 
      Cycle Period:    41,040 yr
Rotation:
      Direction:    West-to-East
      Period:
            Synodic ("Day" in Earth hours):    24.00
            Sidereal (in Earth hours):    23.9345
Albedo (geometric):    0.37
Magnetosphere
      Solar Interaction

View Rotating Earth in 3-D:  super 3-D animations from Robert Vanderbei's great site.  Drag Earth to see the poles; but if you do, view always rotates left to right, not around Earth's axis.  (Requires browser supporting  WebGL )
View Earth at Night in 3D

Earth's Surface:
      Land Area:    29.2%
      Area Covered by Water:    70.8%
      NASA / JPL's Photojournal pages for Earth
Maps of Earth's Surface:
      2048x1024 pixels
            Current Day & Night Map from USNO  (high-res,
                  takes a moment to load)
            Land, Ocean Color & Shaded Topo
            Land, Ocean Color & Sea Ice
            Land, Ocean Color, Sea Ice & Clouds
            Land, Ocean Color, Sea Ice & City Lights
      2048x2048 pixels
            Western Hemisphere
            Eastern Hemisphere
      USGS "This Dynamic Planet" Very High Res PDF
            Front   Back
      USGS "This Dynamic Earth"  online edition
      Link to "This Dynamic Planet" site
      NASA GSFC Tectonic Plates in Color
      NASA GSFC Plate Boundaries: Oceans Drained
      USGS How Plate Tectonics Works 
      University of Kentucky's:  Plate Tectonics
      NOAA's Natural Hazards Viewer
Maps & Vids of Earth's Paleo-History:
      EarthGuide's superb  Global Plate Reconstructions
      From USGS, the  Breakup of Pangaea

       © 2010-13 "SkyMarvels.com"
Copying NOT permitted! USNO Standard Time Zones Map

Earth Atmosphere:
      Structure:
            NASA Graphic 1
            NASA Graphic 2
            NASA Video ascending through Atmosphere
      Composition

Earth Climate Zones

NOTE:  to see Earth's internal structure, hover your cursor over our home planet's Northern Hemisphere in the image at upper-right.
      Earth Structure Video
      Previously Undiscovered Radiation Belt

Number of Moons:    1    (Luna, aka "The" Moon)
      Compare to Other Moons
      Spin-Orbit Resonance with Earth:     Yes, 1 to 1
            (so the same side of Moon always faces Earth)
      View Earth-Moon Barycenter video
      View Moon's Orbital Position & Phase video

Ring System:    No

Planet Classifications:
      Inner Planet (along with Mercury, Venus & Mars)
      Terrestrial Planet (defines term)
      Reference Planet:
            Planets with smaller orbits are "Inferior" Planets
            Planets with larger orbits are "Superior" Planets

Orbit:   (1.6.x)   (1.4.1)
      Period (sidereal) :    365.2564 solar* days
      Period (tropical) :    365.2422 solar* days
      Distance from Sun:
            Mean:    1 AU (essentially defines measurement)
            Mean:    149,597,900 km
            Perihelion:    147,098,000 km
                  Date of:    betw. Jan 2 and Jan 6 (current era)
            Aphelion:    152,096,400 km
                  Date of:    betw. Jul 3 and Jul 7 (current era)
      Velocity:
            Mean:    107,200 km/hr
            Min:    105,444 km/hr
            Max:    109,444 km/hr
      Eccentricity:    0.0167
            Drag slider to 0.016 to  view eccentricity 
      Inclination to Ecliptic:    0° (Earth's orbit IS Ecliptic)
      Milankovitch Cycles 
            Eccentricity Cycle:    approx. 100,000 yr
            Obliquity Cycle:    approx. 41,000 yr
            Apsidal Precessional Cycle:    approx. 112,000 yr

Axial Precessional Cycle:    25,800 years 
Precessional North Axis Direction:  (J2000)
      Right Ascension:    18h 0m 0s   (270.00°)
      Declination:    66° 33' 38.55" (66.56°)
      In Constellation Draco

View of Earth in CELESTIA:
      With Location Labels ON:  (1.6.x)   (1.4.1)
      With Location Labels OFF:  (1.6.x)   (1.4.1)

*Earth mean solar day = 24.0000 hours (24h00m00s)
  Earth sidereal day = 23.9345 hr (23h56m4.1s)

Partial Information Source: NASA Fact Sheets


ADJECTIVES MEANING
"pertaining to Earth"

      earthly, earthy
      terran (often caitalized), terrestrial, terrene (all from Latin: Terra)
      telluric, tellurian


EARTH'S SEASONS

EQUINOXES & SOLSTICES THROUGH MARCH 2014

From NASA, here's a nice graphic that explains  Why Earth Has Seasons.

From NASA, here's a nice Flash demo that helps you further understand  Earth's Seasons.  You even can turn on Closed Captioning (CC) to see text.

Though its 2 primary views display Earth's rotation at different speeds, here's a tool (in Dutch) similar to the one in the previous paragraph.  Moreover, this one lets you  Easily Find Earth's Current Tilt Relative to the Sun.  In addition you can change a few Settings to view how Earth's varying tilt throughout the year produces the seasons and affects the lengths of our days and nights.  Changing the month is most instructive.  (Note: in this animation the Vernal Equinox is essentially toward the bottom of your screen in its Northern Hemisphere view and outward toward you in its Oblique view.)

Showing the relationship between where Earth is in its orbit and the length of its days, here's a nice animation from the Santa Barbara Physics Department site.  Note that its shadow does not account for twilight and, in the part of the animation showing Earth's orbit, the direction of the Vernal Equinox is out from the screen toward the viewer (the reverse orientation of the two preceding demos.)  Length of Earth's Days at Various Times of Year.

Here's a nice interactive Flash demo that lets you relate the Sun's location on the sky to the season.  The Sun's Location Along the Zodiac at Various Times of Year.  Drag its red pointer right and left over the names of the months.  You can also drag the Zodiac itself.

Here's a nice interactive Flash demo that lets you relate where the Sun rises and sets on your horizon to the season.  How Far North and South the Sun Rises and Sets at Various Times of Year.


CURRENT AURORA FORCASTS

      OVATION Forecast:
                  Northern Lights: Aurora Borealis
                  Southern Lights: Aurora Australis


Image credit: NOAA / NWS Space Weather Prediction Center


EARTH'S PRECESSION

Earth's precession is its gradual "wobble" that causes each of our home planet's poles to trace a circle against the background stars every 25,800 years.  The result of gravitational forces primarily of the Sun and the Moon on our planet's equatorial bulge, this fundamental motion of Earth is not unlike that of a precessing gyroscope.  This motion causes our planet to have different North Stars during its 25,800-year cycle!  Our current North Star is Polaris (alpha Ursae Minoris.)

Unlike Earth's rotational axis, its "precessional axis" is essentially fixed.  While its north end points toward the constellation Draco, its other end points toward the southern constellations of Dorado and Pictor.  Around this axis, the direction of Earth's wobble is clockwise when we look down on Earth's Northern Hemisphere.

From the King's Centre for Visualization in Science (KCVS), here's a nice Flash demo that shows  Where the North Celestial Pole Points Over Earth's 25,800-Year Precessional Cycle.

You can find an explanation of how you may view Earth's precession in CELESTIA 1.6.x on  our Tips page.


TOURING THE OCEAN BOTTOM
video credit: NOAA, US Dept of Commerce

EARTH'S WATER CYCLE
video credit: NASA

WATCHING EARTH BREATHE
video credit: NASA/JPL Caltech

NASA: Aquarius Ocean Circulation
video credit: NASA/Goddard Space Flight Center

EARTH AT NIGHT
video credit: NASA Earth Observatory

EARTH FROM ORBIT 2012
video credit: NASA

IMAGE Spacecraft Picks up Earthly Aurora
video credit: NASA/IMAGE Mission

NASA: A Landsat Flyby
video credit: NASA Goddard Space Flight Center

Also check out the videos on our  Earth Weather  page.

DIRECT LINKS TO OTHER NASA VIDEOS

You must have the noted player installed to view these.  Note: you might have to click on these more than once, as some NASA servers (like http://svs.gsfc.nasa.gov in particular) can be temperamental and slow to connect.  If a video does not load, try again at another time.

Draining the Oceans.  Intriguing View of Earth without its Oceans!  (QuickTime)  Video Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.  U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center, 2006, 2-minute Gridded Global Relief Data (ETOPO2v2).  The Blue Marble Next Generation data is courtesy of Reto Stockli (NASA/GSFC) and NASA's Earth Observatory.

Ocean Current Flows Around the Mediterranean Sea.  (Windows Media Player or QuickTime)  Video Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

A Tour of the Water Cycle.  (Windows Media Player or QuickTime)  Video Credit: NASA/Goddard Space Flight Center.

Hourly Evaporation from the GEOS-5 Model.  Note how evaporation, fueled mainly by the Sun, varies with day and night much more greatly over land than over the oceans.  (QuickTime)  Video Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio The Blue Marble data is courtesy of Reto Stockli (NASA/GSFC).

1997 Auroral Substorm from POLAR Spacecraft.  (QuickTime)  Video Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

DIRECT LINKS TO MEDIA
OFFERED ON OTHER SITES

From the Night Skies Network site, here's a very nice  Interactive Time Zones Map.

From Wikipedia with data from the CIA World Factbook, here's a nice high-resolution map of the  Standard Time Zones of the World.

From the US Naval Observatory site, here's a nice high-resolution black-and-white  Standard Time Zones Map.  And here is the  PDF Suitable for Hi-Res Printing.

See how our climate is changing with  NASA's Climate Time-Machine

Also check out this great interactive tool:  NASA's Eyes on the Earth .  (Requires: JAVA.)

Discover the application of space-related discoveries and improvements in everyday things all around you in this very cool 3-D feature:  NASA @ Home and City.


EARTH AT PERIHELION AND APHELION

When is Earth at perihelion and aphelion, respectively the points in its orbit closest to and furthest from the Sun?

Contrary to popular belief, Earth is closest to the Sun during the Northern Hemisphere's winter NOT summer!  Conversely, Earth is farthest from the Sun during the Northern Hemisphere's summer NOT winter!  Our seasons are not caused primarily by Earth's varying distance from the Sun, but rather by Earth's changing tilt in its orbit relative to the Sun!

In contemporary times Earth is generally closest to the Sun between January 2 and January 6, and farthest from the Sun between July 3 and July 7.


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Planet Comparison HD vid.


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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

ISS (Int'l Space Station):
    Current Location


USGS's LATEST

Daily Earthquake Map


NASA's LATEST

Earth from Space Today

ISS (Int'l Space Station) Info:

      Live ISS Stream
      Spot the Station


ESA's LATEST

ISS Location

Follow ESA Missions


LATEST TIDE DATA

Data from  NOAA's National Ocean Service (NOS).


EARTH FUN FACTS

Roughly 90% of our planet's human population resides in the Northern Hemisphere!  Here's a very cool Chrome Experiment that shows this with Earth as a 3-D graph:  World Population  (Requires  WebGL  browser)

Because Earth rotates, it bulges at the equator.  The result is that sea level at the equator is about about 21 kilometers (about 13 miles) further from Earth's center than sea level at the poles!

At present, glaciers blanket roughly 1/10 of Earth's land area.  During the last major Ice Age about 10,000 years ago, they blanketed almost 1/3 of Earth's land area!

Only about 3% of Earth's water is fresh water; 97% is salt water!

The umbra, the dark portion of Earth's shadow, has an average length nearly equal to the diameter of the Sun!

EARTH INTERACTIVES

QUICK ACCESS LIST

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

An awesome demo of many cool Earth views in 3-D from  Cesium.

View Rotating Earth in 3-D  (Requires  WebGL  browser)

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

NASA's Eyes on the Earth .  (Requires: JAVA.)

From UNL here's a very nice Flash interactive illustrating  Latitude and Longitude

From the Santa Barbara Physics Dept site, here's the:  Length of Earth's Days at Various Times of Year

Similar to the interactive above, this one lets you  Easily Find Earth's Current Tilt Relative to the Sun

From UNL here's a fantastic Flash interactive that lets you study what produces  Earth's Seasons  during our yearly journey around the Sun!

Here's KCVS's  Where the North Celestial Pole Points Over Earth's 25,800-Year Precessional Cycle

Here's a KCVS cool tool:  Newton's Cannon  that illustrates Earth orbits.

From the Night Skies Network site, here's a nice  Interactive Time Zones Map

From U. of Colorado's LASP site, here's an exploration of the greenhouse effect and planetary atmospheres in:  Goldilocks and the Three Planets!  It's excellent, and you'll even see a movie of a "dust devil" on Mars!

Is our climate changing?  Find out here with  NASA's Climate Time-Machine

Discover the application of space-related discoveries and improvements in everyday things all around you in this very cool 3-D feature:  NASA @ Home and City

NASA's  ISS Flight Attitudes

NASA's  ISS: Painting the World Green

From the ESO, here's a very nice 3-D interactive of the  Hubble Space Telescope

Roughly 90% of our planet's human population resides in the Northern Hemisphere!  Here's a very cool Chrome Experiment that shows this with Earth as a 3-D graph:  World Population  (Requires  WebGL  browser)

This nice map, created by André Christoffer Andersen, estimates  World Population by Latitude & Longitude.


SKYMARVELS™
CELESTIA ADD-ONS FEATURING EARTH

Solar
Eclipse Finder

Lunar
Eclipse Finder


SKYMARVELS™
POSTERS FEATURING EARTH

Time Zones

Earth's Tides

Our Corner of the Cosmos

Anatomy of the Milky Way


SKYMARVELS™
VIDEOS FEATURING EARTH

The Sun's Signature

Earth's Structure (short)

Earth's Structure (longer)

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

 

How Big Is Our Moon?

The Same Side of the Moon Always Faces Earth

The Earth-Moon Barycenter

The Solar System Barycenter

Phases of the Moon