By cosmic standards the asteriod Ida (above)—only as large as the Hawaiian island of Molokai—is "pint-sized"!  (1.6.x)

Intriguing coincidences are found on cosmic scales.  The Sun is 400 times larger in diameter than our Moon AND 400 times farther away!  So solar eclipses can look like  this . . .  (1.6.x)

And just how large are objects like  Voyager  and other famous spacecraft?

Note: after running a link like the one above for the potato-shaped Ida, Right Drag with your mouse to get a sense of the 3-dimensional aspects of its structure and orbit.

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

ZOOM IN ON
THE UNIVERSE

In a Universe possibly infinite the  "observable" universe  is all that potentially can be per- ceived from Earth, taking into account the expansion of the Big Bang!  In accord with rel- ativistic physics, it is calcu-lated to be a spherical region 93 billion light years across, and is a vast web of filaments and superclusters containing perhaps trillions of galaxies!

Having zoomed in by a factor of 10 billion in the six views above has finally delivered us to the domain of the Sun!  The immense  Oort Cloud  is acknowledged to constitute the peripheral boundary of the Solar System.  Enlarged in the "exploded view" to the right, our Solar System has a scale far more vast, complex and crowded than could once have been imagined!


ELEMENTS OF THE MAJOR PLANET ORBITS

    Period
(Earth
Years)
Orbital
Inclin-
ation
Peri-
helion
(au)
Aphe-
lion
(au)
   
Mer 0.24 7.00° 0.307 0.467
Ven 0.62 3.39° 0.718 0.728
Ear 1.00 0.00° 0.983 1.017
Mar 1.88 1.85° 1.381 1.666
Jup 11.86 1.30° 4.950 5.459
Sat 29.46 2.49° 9.041 10.12
Ura 84.01 0.77° 18.32 20.08
Nep 164.8 1.77° 29.71 30.39

The distances between the planets' orbits are far from uniform—increasing outward from the Sun!

ENLARGED VIEW OF THE INNER PLANET ORBITS


  KEEP SAFE!  It is never
  safe to look directly at the real Sun with the naked eye!  Moreover, looking at it—even for an instant—through either a telescope, binoculars, camera or similar instrument without adequate safeguards can cause permanent blind- ness!  NEVER DO IT!  To learn how you may safely observe the Sun, consult your local planetarium or observatory.

Seeing how big the Sun looks from all the planets gives us another way to appreciate the immense
scale of the Solar System!

       

The average Sun-Earth distance is a convenient yardstick for describing distances in the realm of our Solar System's major planets.  It is called the Astronomical Unit (au),
by definition equaling 149,597,870.7 km.

 

NUMBERS OF ASTRONOMICAL OBJECTS

As well as the distances and sizes encountered in the uni- verse, the numbers of the di- verse objects that comprise it are mind-bending!  They too provide an important sense of the Scale of the Cosmos!  Here are a few lists—by no means complete—that make us realize that universe is a very busy place indeed!

IN OUR SOLAR SYSTEM

 
Objects
Ob-
served
Esti-
mated
———— ——— ———
Stars1 11 11
Major Planets1 81 81
   Moons1 1881 100s1
Dwarf Planets1 51 millions1
   Moons1 91 millions1
Minor Planets1 106+1 millions1
   Moons1 36+1 millions1
Comets1 6,600+1 trillions1

While much of our galaxy has been catalogued, the majority still remains unstudied.

IN OUR GALAXY

 
Objects
Cata-
logued
Esti-
mated
———— ——— ———
Stars1 109+1 2x10111
Star Systems1 4500+1 millions1
Star Clusters1 11000+1 10s of th.1
Globular Clus.1 150+1 100s1
Exoplanets1 4000+1 billions1
Nebulae1 100s1 1000s1

In the list below for the entire universe, educated guesses only can be made.

IN THE UNIVERSE

Objects Estimated
———— —————
Stars1 1022 – 10241
Exoplanets1 1024+1
Nebulae1 1015+1
Galaxies1 1012+1
Galaxy Clusters1 109+1
Galaxy Superclusters1 107+1

". . . the total number of stars
in the universe is greater than all the grains of sand on all the beaches of the planet Earth."
           -Carl Sagan, COSMOS

Of course, with new observa- tions, these figures are being updated constantly—mostly upwards, it often seems.  The point to draw from this is that these numbers represent diz- zying orders of magnitude!


Light requires about
6 seconds to travel from Jupiter to Callisto!

"From the infinitesimal to the infinite . . ."

SCALE OF THE COSMOS

Astronomy grapples with concepts from the infinitesimal to the infinite!  Nuclear particles  which power stellar ob- jects are so tiny, while  galaxies  and the  filaments  com- posed of their  superclusters  are so huge, that they tax our capacity to comprehend their true dimensions!  But let's give it a try, with the aid of  Scale of the Universe 2, Nikon's  Universcale  and  The Size of Space.

Elsewhere on this page we'll also try to give you a sense of the scale of other objects that we all recognize, but which may be larger or smaller than you think!


SCALE OF THE "OBSERVABLE" UNIVERSE

From the  Hubble eXtreme Deep Field photograph    the observable universe  is now known to contain hundreds of billions—perhaps trillions!—of galaxies!  And it is now calculated to have a diameter of tens of billions of light years, though there is still debate as to its full extent.  To help us appreciate how large the observable universe is and the galaxies it contains, this  awesome video from the Sloan Digital Sky Survey  accurately shows the rela- tive positions of 400,000 galaxies!  Yet this represents only a tiny fraction of the observable universe and all the galaxies in it!  If the latest calculations are correct, then what we "can observe of our universe" must contain mil- lion of times more galaxies than the video displays!  And we mustn't forget that  millions to trillions of stars com- prise each galaxy!  These vast amalgamations of matter and energy, huge in themselves, are arranged in even larger  galaxy clusters    and  superclusters  that make up the immense  galaxy filaments    that stretch across the universe in incredibly complex  3-dimensional webs  and networks!  Millenium Simulation 


SCALE OF GALAXIES

Galaxies, often described as "island universes", are im- mense collections of star systems, nebulae, interstellar matter and energy bound by gravity.  Often forming clus- ters, galaxies are generally classified by shape  as spiral (which may be barred, as shown just below), elliptical or
irregular, most from a few thousand to half a million light years across.  This sampling of galaxy size comparison charts  #1   #2   #3   #4  begins to give us an idea of how varied the scale of galaxies can be.  Much more on gal- axies is available on our  Deep-Sky Objects  page.


SCALE OF OUR GALAXY, THE MILKY WAY

Evidence indicates that  our own galaxy the Milky Way is a barred-spiral about 100,000 light-years across  .  This is immense by any earthly standards, and it is interest- ing to note that, even as late as the 1920's, the Milky Way was believed to constitute the entire Universe!

The ground-breaking observations of Edwin Hubble in the 1920's established conclusively that the Universe is far larger than was previously believed.  Moreover, the satellite telescope named after him has shown that hun- dreds of billions—perhaps trillions!—of galaxies exist in the cosmos, whose true extent is so staggering that it is nearly unimaginable!  Compared to a sphere with the di- ameter of the Milky Way, the volume of the known Uni- verse is now believed to be at least 20 quadrillion times larger!  That's a huge number: a 2 followed by sixteen zeroes (20,000,000,000,000,000)!  In fact, this figure is among some of today's more conservative estimates!

Here's a link to the engrossing  100,000 Stars  Chrome Experiment 3-D visualization.  While it does not depict our Solar System's orbital tilts and eccentricities, it does nicely map many  local stars, and reveals the scale of the cosmos from our Sun to the edge of the Milky Way!

This video from NASA shows the  Eventual Collision & Merging of the Milky Way with the Andromeda Galaxy.


SCALE OF THE CONSTELLATIONS

One interesting aspect of the constellations is that their shapes depend on viewing them from Earth in the pres- ent era.  If we view them from far out in space, say light years from Earth, or view them from far in the past or the future, then  Constellation Shapes Change  enormously!  Viewed from far out in space, the positions of their stars are distorted beyond recognition.  The motions of those same stars over eons has the same effect.


SCALE OF THE SOLAR SYSTEM

Above we see the scale of the Solar System expressed both in kilometers and in light-time.

And from NASA / JPL-CalTech, here's a fascinating look at a  Logarithmic Scale of our Solar System.  This means that, with the Sun at 0 (zero), beyond 1 AU the distance marked off between any two adjacent numbers is ten times greater than the distance marked off immediately before it!  Though some persons find them confusing, logrithmic-scale diagrams  allow the representation of incredibly vast distances in a limited amount of space.

Don't forget that our page on the  Solar System  offers overhead views of its more central region, where the ma- jor planets orbit the Sun.  This is further explored below.

A CROSS SECTION OF THE SOLAR SYSTEM

Our Solar System is so vast and comprised of so many objects—some "relatively" near one another, yet most separated by great distances—that depicting large parts of it to scale is difficult.  So you will have to look closely just above and to the left.  Able to show only one side of the Solar System out to Neptune, this cut-away displays the 8 major planets' perihelia and aphelia distances  (i.e. when they are closest to and farthest from the Sun), and their orbital inclinations relative to the Ecliptic—all to scale.  Also indicated are regions where  Smaller Worlds  populate the Solar System: the Asteroid Belt, the expan- sive realm of the Centaurs, and the edge of the Kuiper Belt, which stretches from the orbit of Neptune to over 50 au from the Sun!  (Note: when you hover above to reveal the "relative" sizes of the planets, their scale is hugely enlarged compared to that of the cross section!)


APPARENT SIZE OF THE SUN
FROM THE MAJOR PLANETS

Below and at left, slide the blue pointer left and right "or" click along the Astronomical Unit (au) scale (which also shows light-time) to  inspect the Sun's relative apparent size from from Mercury all the way out to Neptune!  Most browsers (though not Safari) also permit you to use your keyboard Arrow Keys to "fine-tune" your slider position.  Clearly the Sun, which simultaneously scorches Mercury and bakes Venus, is not nearly so prominent in the frigid skies of the Solar System's distant outer planets!

This page opens with the Sun (below) seen from Earth.  The perihelia and aphelia of the major planets are shown

in the cross section just above the zoomable Sun.  Note that Venus's and Earth's orbits are so circluar that their extremes of distance are less than one pixel apart at this scale!  At the Inner Planets in particular you will have to look closely—or zoom your browser—to pinpoint your distance!  Mercury is especially seared by the Sun, and much more at its perihelion than its aphelion!  Mars is close enough to the Sun that  the Martian seasons are affected by the planet's orbital eccentricity!  Uranus has the greatest difference between its nearest and farthest distances from the Sun!  Yet the planet's orbit is so large that  the Sun does not look much different from Uranus's perihelion to its aphelion!  What other intriguing facts will you discover from planet to planet—and in between?

As you examine all this, you should also check out the  Relative Intensity of Sunlight at the Planets.  Since the human eye can adapt so well to varying light levels, you may be surprised by what "daylight looks like" as you venture further out in the Solar System.


SCALE OF THE SUN-EARTH DISTANCE

Below, the partial cross section of the Ecliptic shows the Sun (tiny, at left) and its distance from Earth in their cor- rect relative dimensions.  However, even here in the in- ner Solar System we are forced to face the broad ranges of sizes and distances that characterize our universe.  At this view's scale Earth's size must be exaggerated.  If it were represented proportionately here, Earth (tiny dot at right) would be less than 1/10 of a pixel in diameter!

By earthly standards, one Astronomical Unit (au) seems very large.  Yet by the standards of the universe, it is ac- tually not quite so impressive.  To the edge of the Oort Cloud is one light year from the Sun, or over 63,000 au!  And the nearest stars are over four times farther away!


SCALE OF THE SUN

The Sun is so immense that the
Moon's orbit would easily fit inside!

And don't forget to check out our  Sun  page.


SCALE OF STARS

Stars vary greatly in size, brightness, lifetimes, even in the nuclear reactions that power them.  For example, a neutron star and a quark star would fit in the Grand Can- yon, while the largest supergiants and hypergiants have diameters as large as the orbit of Saturn!  Much on the scale of stars is available on our  Stellar Objects  page.


SCALE OF MAJOR MOON DISTANCES

The cross sections just below show the distances of the major moons of Earth, Jupiter, Saturn, Uranus and Nep- tune, all in the same scale, confirming that major moons can orbit their parent planets at a range of distances.

Light requires about
4 seconds to travel from Saturn to Titan!

Iapetus orbits Saturn
at over twice Hyperion's distance, straying quite far from the ringed plan-
et's equatorial plane.

ELEMENTS OF NEPTUNE'S MAJOR MOON ORBITS

    Period
(Earth
Days)
Orbital
Inclin-
ation
Radius
(103
km)
   
Eccen-
tricity
   
Pro 1.122 0.04° 117.647 0.0004
Tri 5.877 157.34° 354.76 0.000016
Ner 360.1 7.23° 5,513.4 0.7512

Proteus orbits very close to Neptune's equatorial plane, while Triton and Nereid stray far from it!




Click to send Photon

ELEMENTS OF THE MARTIAN MOON ORBITS

    Period
(Earth
Days)
Orbital
Inclin-
ation
Radius
(103
km)
   
Eccen-
tricity
   
Pho 0.319 1.08° 9.378 0.0151
Dei 1.262 1.79° 23.459 0.0005

Mars and its moon distances to same scale as Earth-Moon Distance directly above.  Yes, in reality  the Martian system is quite small.  It would fit in- side any of the Gas Giants!

 

SCALE OF THE COSMOS ACTIVITIES

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

Use the Earth-Moon Distance diagram above for this.  Have a conversation with a friend, but between your exchanges click to send photons as in- dicated just above.

Then, for your Earth-Moon conversation to be accurate, you must wait for the 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, but it's not nearly as fun as watching the photon!

For a variation, try it with you and your friend facing away from one another—or with a partition between you.  Is the delay a little spookier this way?  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!


REPEAT THE CONVER- SATION ABOVE, THIS TIME BETWEEN SATURN & TITAN OR BETWEEN JUPITER & CALLISTO!

Try a planet-to-moon conver-sation similar to the one you had above, but this time at Saturn or Jupiter!

As you can verify a few para- graphs above, the time delay between your Saturn-Titan exchanges will be close to 8 seconds (4x2), while between Jupiter-Callisto the delay will stretch to an even more dis- orienting 12 seconds (6x2)!

Yes, as we venture beyond the comfortable realm of our home planet, communication is not going to be easy!


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 to show others!  If permitted, you might even want to paint the yardstick black and add continents 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!


MAKE A SCROLL THAT
SHOWS THE SCALE OF THE SOLAR SYSTEM

From JPL, here is an easy to perform activity that reveals in a dramatic way the  scale of the Solar System.  This one will probably surprise many of you!  You'll find that terms like the "Inner Planets" and the "Outer Planets" are very appropriate!  Moreover, you can take your scroll and dem- onstrate it nearly anywhere!


CREATE A LARGER "OUTDOOR" MODEL OF THE SOLAR SYSTEM!

The  Kinesthetic Radial Mod- el of the Solar System  is an excellent outdoor class activ- ity that will have students on their way to comprehending the nature, scale and make-up of our planetary system!  You can even show current planet locations to make it a "working model"!  Creating this "walk-thru" replica will engage everyone involved, so be sure you take lots of photos along the way!  You may even consider planning a "Solar System Appreciation Picnic" among the planets!  There are loads of opportu- nities for fun learning here.


MAKE A COOL PAPER MODEL OF THE JWST!

The  James Webb Space Tel- escope  will tell us even more about the scale of the cosmos!  Make your cool model and submit photos of it to NASA!


CREATE YOUR OWN
GALAXY CLUSTER

From NASA's Space Place, create your own corner of the Universe by  Making a Galac- tic Mobile.  Will your creation be just a  cluster, or will it be an awesome  supercluster?

 

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.

  • 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 aspects 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.


Hyperion moves in the
most eccentric orbit of
Saturn's major moons.

ELEMENTS OF SATURN'S MAJOR MOON ORBITS

    Period
(Earth
Days)
Orbital
Inclin-
ation
Radius
(103
km)
   
Eccen-
tricity
   
Mim 0.942 1.53° 185.52 0.020
Enc 1.370 0.00° 238.02 0.005
Tet 1.888 1.86° 294.66 0.000
Dio 2.737 0.02° 377.40 0.002
Rhe 4.518 0.35° 527.04 0.001
Tit 15.95 0.33° 1,221.8 0.029
Hyp 21.28 0.43° 1,481.1 0.104
Iap 79.33 14.72° 3,561.3 0.028

The five major moons of Uranus orbit in nearly circular orbits.  Four orbit the "tipped over planet" very close to its equato- rial plane, but Miranda's orbit is tilted about 4⅓°.

Triton orbits Neptune in
a retrograde direction
and is thought to be
a "captured moon"!

Light requires about
1 second to travel from Neptune to Triton!


On average light requires about 1¼ seconds to trav- el from Earth to our Moon!


However moons cannot orbit too close to their parent planets!  Within a planet's  "Roche Limit", moons will be torn apart by tidal forces!  The rings of the Gas Giants—partly denoted here—are examples of this effect.

ELEMENTS OF URANUS'S
MAJOR MOON ORBITS

    Period
(Earth
Days)
Orbital
Inclin-
ation
Radius
(103
km)
   
Eccen-
tricity
   
Mir 1.413 4.34° 129.90 0.0013
Ari 2.520 0.04° 190.90 0.0012
Umb 4.144 0.13° 266.00 0.0039
Tit 8.706 0.08° 436.30 0.0011
Obe 13.46 0.07° 583.50 0.0014


SCALE OF THE EARTH-MOON DISTANCE

Probably because they are addressing a different issue than size, most depictions of Earth, the Moon and the distance between them do not show them at their proper relative scale.  In the partial cross section directly below they are represented accurately—including the extremes of perigee and apogee of the lunar orbit!  For reference, you may also view the time required to send a photon to the Moon and bounce it back to Earth!  Clicking as noted at left will confirm that—due to the Scale of the Cosmos —even light-speed communication with our nearest ce- lestial neighbor is not instantaneous!  (See below left.)

Moon Distances (in Earth equatorial diameters):
Min Perigee = 27.9, Average = 30.1, Max Apogee = 31.9


SCALE OF THE MAJOR PLANETS

Here's an interesting way of viewing the relative sizes of the planets.  Note how small the Inner Planets (Mercury, Venus, Earth & Mars) are compared to the Outer Planets (Jupiter, Saturn, Uranus & Neptune.)

Here's an older but effective interactive for a side-by-side  Planet Size Comparison.  Select planets and click on "COMPARE".  Or use the  NASA/JPL "Eyes" Orrery  to compare them in 3-D!

Axial Tilts of the Planets 


SCALE OF EARTH AND THE MOON

Even the two worlds that we consider the most familiar, Earth and the Moon, can surprise us when shown in the same relative scale!  Our video  How Big Is Our Moon?  will help clear things up!  And Earth and our Moon are shown in the correct relative scale just below—enlarged in the foreground of their view with the lunar orbit.  (P.S. Don't forget to check out our  Moon  page.)  As a bonus here is the Moon's 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

You'll get a good sense of the true relative sizes of Earth, the Moon and the lunar orbit at 3:27 into  this video,  as Earth and the Moon accurately orbit their barycenter.

COMPARE MOON TO EARTH'S CONTINENTS

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!


SCALE OF COMMON
EARTH-SATELLITE ORBITS


SCALE OF THE ISS
The International Space Station

This enlightening image from NASA shows the scale of the ISS, the International Space Station.  Is it larger or smaller than you thought?  This is the largest structure ever assembled in space by humankind.  To view in high resolution and save the high-res PDF,  click here.  And from ESA here is a  high-res exploded view of the ISS.


SCALE OF THE HUBBLE AND THE
JAMES WEBB SPACE TELESCOPES

This comparison really has us excited!  Why?  Because the  James Webb Space Telescope (JWST)    will be able to peer deeper into the cosmos and therefore fur- ther back in time than Hubble.  In fact, it will peer back over 275 million years closer to the Big Bang than Hubble can!  Where is Webb?  Orbit

Hubble was about the size of an average school bus.  In contrast, the James Webb Space Telescope will be more on the order of the size of a tennis court!

Scroll the image below to see how much further into space and time the JWST will peer, thereby increasing our understanding of the scale of the cosmos.

Scroll the image below to compare the electromagnetic wavelengths used by Hubble, the JWST and other satellites and observatories to study the cosmos.

Interactive Electromagnetic Spectrum  Drag white bar.


SCALE OF THE JUNO SPACECRAFT

Compare to Other Spacecraft


SCALE OF THE MARS CURIOSITY ROVER

Though the Mars rovers have come in a variety of sizes, the Curiosity Rover is roughly the size of a small SUV.




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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

FUN FACTS ABOUT THE
SCALE OF THE COSMOS

If  the conservative figure for the radius of the observable universe—roughly 14 billion light years—is correct, then the edge of the observable universe is over 5,500 times further than the Andromeda Galaxy from us!

If  the relativistic figure for the radius of the observable universe—roughly 46 billion light years—is correct, then the edge of the observable universe is over 18,000 times further than the Andromeda Galaxy from us!  This is the estimate accepted by most modern physicists.

Currently accepted evidence overwhelmingly suggests that everything that makes up our known Universe was once contained in a space smaller than a quark!

The entire orbit of our Moon would fit inside the Sun with room to spare!

The ratio of the diameter of a proton to the diameter of a hydrogen atom (in a "ground state") is about 1 to 62,500!  The ratio of the diameter of the Sun to the diameter of Neptune's orbit is only about 1 to 6,400!


TIME SCALE OF
THE UNIVERSE

When considering the "Scale of the Cosmos," it is not only physical dimension that we should reflect upon, but also time.  From the Hubble site, here are a few images that illustrate the "Time Scale of the Cosmos!"

Cosmic Epochs

Seeing Back into the Cosmos

And here's one from NASA's  WMAP pages.

Big Bang Expansion 

And here's a cool interactive look at the scale of time.

Here Is Today

And below you can compare what you've just learned to the time-scale of the life of the Sun.

From the USGS, here's their  Geologic Time: Online Edition

From the GSA, here's a PDF of their  GSA Geologic Time Scale  chart.


THE VASTNESS OF
THE SOLAR SYSTEM

Many persons are amazed to see Solar System distances shown in their correct rela- tive scales—as in the cross sections below.  That the In- ner Planet orbits occupy so small a part of the Solar Sys- tem is a revelation to many.

Realizing this helps one ap- preciate the wondrous feats of sending spacecraft to the planets, especially the Outer Planets—and beyond.  Juno  (above) is but one of several spacecraft that have visited Jupiter!  New Horizons  has

flown past Pluto, so far away that it could not be included in the cross sections below!  And the  Voyager  spacecraft have long departed the realm of the major planets!

Exploring further you will see why even distant Pluto can no longer be considered the outer limit of our Solar Sys- tem!  No, our Solar System is far more vast than that, its encircling Oort Cloud extend- ing perhaps a full light year from the Sun!

Hover over cross sec- tion below for "relative" planet sizes and tilts.

"APPARENT" SIZE

The heavens in never-ending motion, how big an object "looks to us" at a particular time is often important.  For instance, during a central solar eclipse, the "apparent" sizes of the Sun and Moon determine whether it will be seen as total or annular.

Likewise, transit and occul-tations times are affectd by apparent planet sizes.  Now you can find them easily!


(to update, reload page)

Current Apparent Sizes:

        Sun vs Moon

    Major Planets

This cross section is a
little different from the
one further above.  Mainly meant to show distance, it does not show each plan- et's orbital inclination.

SCALE OF THE COSMOS INTERACTIVES

QUICK ACCESS LIST

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

Here are two awesome size- comparison interactives that will take you from the infini- tesimal to the infinite!

    Scale of the Universe 2

    Nikon's Universcale

The  Size of Space  also re- veals the sizes of objects in the universe, but nothing smaller than an astronaut. 

The  Cosmological Redshift Simulator  lets you study the phenomenon that led to the discovery of the Big Bang!

Cosmic Web Visualizations     Select a Newtork Model, (Fixed Length is our favorite), then pan, zoom and filter. Cool filament views!

Gathering Light: Hubble Ultra Deep Field  "enlightens" us about the scales of light and time necessary to peer into really deep space!

From UNL, here's an interac- tive HR Diagram to acquaint you with the  Scale of Stars.

Moon Phaser  an awesome interactive tool!

Earth-Satillite Orbit Sizes


SUN-EARTH DISTANCES
————————————
Perihelion: 0.9833 AU
Average: 1.0000 AU
Aphelion: 1.0167 AU

Earth's Mean Tilt Today
relative to the Sun


PROTON-PROTON
CYCLE

The Sun is notable not only for its overall size, but also for the "minuteness" of the particles responsible for its prodigious output of energy!

Proton-Proton Cycle  .

 

HOW FAR ARE . . .?

The motions of the universe never ceasing, how far vari- ous objects are to be found from Earth is complex.  Some asteroids have passed within a fraction of a light-second of us, while the furthest comets move at the edge of the Oort Cloud, perhaps a light-year away!  This list highlights the distances to various types of Solar System objects, and then the nearest larger-scale objects beyond.

Objects Light Time1
———— —————1
Our Sun1 ~ 8.3 lt-min1
Our Moon1 ~ 1.3 lt-sec1
Nearest Planet1 ~ 2.2 lt-min1
Other Planets1 lt-min to lt-hr1
Other Moons1 lt-min to lt-hr1
Nearest Asteroid1 frac. of lt-sec1
Other Asteroids1 lt-sec to lt-hr1
Nearest Comet1 ~ 6 lt-sec1
Other Comets1 lt-sec to 1 lt-yr1
Nearest Star1 ~ 4.24 lt-yr1
Nearest Nebula1 ~153 lt-yr1
Nearest Galaxy1 ~ 25,000 lt-yr1
Near. Gal. Cluster1 ~ 11x106 lt-yr1


ELEMENTS OF THE GALILEAN ORBITS

    Period
(Earth
Days)
Orbital
Inclin-
ation
Radius
(103
km)
   
Eccen-
tricity
   
Io 1.769 0.04° 421.8 0.004
Eur 3.551 0.47° 671.1 0.009
Gan 7.155 0.18° 1,070.4 0.001
Cal 16.69 0.19° 1,882.7 0.007

The four Galilean Moons —Io, Europa, Ganymede and Callisto—orbit mighty Jupiter very close to its equatorial plane and in nearly circular orbits!