NSCI 314

LIFE IN THE COSMOS

12 - WHERE TO SEARCH FOR LIFE:(A) IN OUR SOLAR SYSTEM – MOONS OF OUTER

PLANETS (CONTINUED), AND OUTSIDE OUR SOLAR SYSTEM –

(B) EXOTIC LIFE AND (C) SUITABLE STARS AND PLANETS

Dr. Karen KolehmainenDepartment of Physics, CSUSB

http://physics.csusb.edu/~karen/

HABITABLE ZONES AROUND OTHER STARS

FOR BRIGHTER STARS:– HABITABLE ZONE IS FARTHER FROM STAR AND

LARGER IN EXTENT (E.G., 5 TO 20 AU FOR AN A-TYPE MAIN SEQUENCE STAR)

FOR FAINTER STARS:– HABITABLE ZONE IS CLOSER TO STAR AND SMALLER

IN EXTENT (E.G., 0.02 TO 0.06 AU FOR AN M-TYPE MAIN SEQUENCE STAR)

– HABITABLE ZONE MAY BE SO SMALL THAT IT IS UNLIKELY THAT ANY PLANETS ARE FOUND WITHIN IT

– IF PLANET IS TOO CLOSE TO STAR, OTHER POSSIBLE PROBLEMS INCLUDE:

• SOLAR FLARES • PLANET’S ROTATION MAY BE TIDALLY LOCKED (MIGHT BE

OK IF ATMOSPHERE CAN SPREAD HEAT AROUND ENOUGH)

MOONS OF SATURN

MOST ARE SMALL BODIES CONSISTING OF A MIXTURE OF ICE AND ROCK, WITH NO ATMOSPHERES.

TITAN IS AN EXCEPTION: A LARGER ICE/ROCK BODY WITH A THICK ATMOSPHERE.

ENCELADUS SMALL TO MEDIUM-SIZED MOON OF SATURN MIXTURE OF ICE AND ROCK FEW IMPACT CRATERS, NO ATMOSPHERE TIDAL FORCES FROM SATURN CAUSE

INTERNAL WARMING HAS ICE VOLCANOES

– SOME REGIONS NEAR THE SOUTH POLE ARE WARMER THAN THE REST OF THE SURFACE

– CRACKS IN ICY CRUST, MATERIAL CAN SPEW UP FROM BELOW

– FOUNTAINS OF ICE PARTICLES AND WATER VAPOR

– SOME ORGANIC MOLECULES FOUND

IAPETUS MEDIUM-SIZED MOON OF SATURN

HEAVILY CRATERED, NO ATMOSPHERE

LEADING HEMISPHERE IS DARK, TRAILING HEMISPHERE IS LIGHT

DARK MATERIAL IS ORGANIC

MAY BE COLLECTED FROM SPACE AS IAPETUS MOVES IN ITS ORBIT

MORE MOONS OF SATURN

MIMAS – HAS BIG IMPACT CRATER, IMPACT MUST HAVE ALMOST BROKEN MIMAS APART

DIONE OR RHEA? ICE/ROCK COMPOSITION NO ATMOSPHERE NOT GOOD CANDIDATES FOR LIFE

MOONS OF URANUS MOST INTERESTING ONE IS

MIRANDA ICE/ROCK COMPOSITION NO ATMOSPHERE NOT A GOOD CANDIDATE FOR LIFE HAS MIXTURE OF DIFFERENT TYPES

OF TERRAIN – OLDER CRATERED TERRAIN AND YOUNGER TERRAIN WITH GROOVES

MAY HAVE BEEN BROKEN APART BY LARGE IMPACT AND REASSEMBLED

TRITON LARGEST MOON OF NEPTUNE RETROGRADE ORBIT - PROBABLY CAPTURED

KUIPER BELT OBJECT INTERIOR OF ICE AND ROCK FEW IMPACT CRATERS SURFACE CONTAINS NITROGEN ICE AND

METHANE ICE ACTIVE SURFACE (ICE MAY COVER LAKES OR

OCEAN OF NITROGEN, METHANE, AMMONIA, AND/OR WATER?)

LIQUID GEYSERS OR ICE VOLCANOES OCCASIONALLY ERUPT

VERY THIN NITROGEN ATMOSPHERE PROBABLY WAY TOO COLD FOR LIFE

THIS COMPLETES OUR “TOUR” OF OUR SOLAR SYSTEM.

WHAT ABOUT LOOKING FOR LIFE BEYOND OUR SOLAR SYSTEM?

WE EXPECT OTHER SOLAR SYSTEMS TO CONTAIN THE SAME TYPES OF OBJECTS AS OUR SOLAR SYSTEM:– A STAR (MAYBE A DOUBLE OR MULTIPLE STAR)– PLANETS– MOONS– SMALLER OBJECTS:

• DWARF PLANETS• COMETS • ASTEROIDS

ADVANTAGES OF PLANETS AND LARGE MOONS FOR LIFE CONDUCIVE TO CHEMISTRY (ATOMS

COMBINING AND RECOMBINING TO FORM MOLECULES)

PROVIDE A RELATIVELY STABLE AND PROTECTED ENVIRONMENT (AT LEAST IN MANY CASES)

SMALL VARIATIONS IN ENVIRONMENT

VARIETY OF INTERFACES BETWEEN LAND, OCEANS, AND ATMOSPHERE

LIFE IN LOCATIONS OTHER THAN PLANETS OR LARGE MOONS?

SMALL MOONS, ASTEROIDS, ETC.– NO ATMOSPHERE - THEREFORE NO LIQUIDS,

EXTREME TEMPERATURE VARIATIONS, AND NO PROTECTION AGAINST ULTRAVIOLET RADIATION

STARS– TOO HOT FOR COMPLEX MOLECULES TO FORM

NEBULAE (CLOUDS IN THE INTERSTELLAR MEDIUM)– LOW TEMPERATURE AND DENSITY CHEMICAL

REACTIONS PROCEED VERY SLOWLY HARD TO IMAGINE COMPLEX MOLECULES FORMING

NEUTRON STARS??

LIFE ELSEWHERE COULD HAVE:

Very similar proteins and DNA sequences to us (if so, a common origin is likely)

Same amino acids and genetic bases as us, but combined into different proteins and DNA sequences (common origin?)

Amino acids and genetic bases, but not the same 20 amino acids and 4 or 5 bases as us

Different monomers, (not amino acids and genetic bases), but still carbon-based polymers of some sort

Different chemistry (silicon-based?) No chemistry at all! (exotic matter, or

interactions other than electromagnetic)

CHEMISTRY INVOLVES COMBINING ATOMS TO MAKE

MOLECULES (INCLUDING MOLECULES BEING BROKEN APART INTO ATOMS, THEN ATOMS REARRANGING AND COMBINING INTO NEW MOLECULES)

BASIS OF ALL LIFE ON EARTH BASIS OF ALL CARBON-BASED LIFE BASIS OF SILICON-BASED LIFE (IF

POSSIBLE) HAPPENS BECAUSE OF

ELECTROMAGNETIC FORCES

FUNDAMENTAL FORCES MANY FORCES ARE ELECTROMAGNETIC FORCES.

– ELECTRICAL FORCES HOLD ATOMS TOGETHER (ATTRACTION BETWEEN POSITIVELY CHARGED NUCLEUS AND NEGATIVELY CHARGED ELECTRONS).

– ELECTRICAL FORCES HOLD ATOMS TOGETHER TO FORM MOLECULES. (ELECTRONS ARE TRANSFERRED OR SHARED BETWEEN ATOMS.)

– “CONTACT” FORCES ARE ELECTRICAL WHEN EXAMINED ON A MICROSCOPIC LEVEL.

– ELECTRICITY AND MAGNETISM ARE CLOSELY RELATED - MAGNETISM IS CAUSED BY MOVING ELECTRIC CHARGES.

GRAVITY IS A FUNDAMENTALLY DIFFERENT KIND OF FORCE

HOW MANY KINDS OF “FUNDAMENTAL” FORCES ARE THERE? WE THINK THERE ARE ONLY FOUR TYPES OF FUNDAMENTAL FORCES.

FUNDAMENTAL FORCES(IN ORDER FROM STRONGEST TO WEAKEST)

NAME RANGE COUPLES TO

STRONG SHORT “COLOR”

ELECTROMAGNETIC LONG ELECTRIC CHARGE

WEAK SHORT “FLAVOR”

GRAVITY LONG MASS

NOTES: (1) “SHORT RANGE” MEANS THAT THE PARTICLES MUST BE WITHIN 10-15 m (0.000000000000001 m) OF EACH OTHER TO FEEL THE FORCE. “LONG RANGE” MEANS THAT THE PARTICLES WILL FEEL THE FORCE EVEN IF THEY ARE VERY FAR APART (ALTHOUGH THE FORCE WILL BE WEAKER IF THE PARTICLES ARE FARTHER APART).

(2) “COUPLES TO” MEANS THAT THIS IS THE PROPERTY THE PARTICLES MUST HAVE IN ORDER TO FEEL THE FORCE OR EXERT THE FORCE ON OTHER PARTICLES.

FUNDAMENTAL FORCES(IN ORDER FROM STRONGEST TO WEAKEST)

NAME EFFECTS

STRONG HOLDS NUCLEI OF ATOMS TOGETHER, CAUSES CERTAIN TYPES OF REACTIONS

BETWEEN PARTICLES

ELECTROMAGNETIC HOLDS ATOMS AND MOLECULES TOGETHER, CAUSES CERTAIN TYPES OF REACTIONS BETWEEN PARTICLES

WEAK CAUSES BETA DECAY (TYPE OF RADIOACTIVE DECAY)) AND CERTAIN TYPES OF REACTIONS BETWEEN PARTICLES

GRAVITY HOLDS PLANETS, STARS, AND GALAXIES TOGETHER

HOW ARE THE FUNDAMENTAL FORCES RELATED TO LIFE?

ANY FORM OF LIFE THAT INVOLVES CHEMISTRY (ATOMS AND MOLECULES) IS BASED ON THE ELECTROMAGNETIC FORCE, BECAUSE THE ELECTROMAGNETIC FORCE IS RESPONSIBLE FOR HOLDING ATOMS AND MOLECULES TOGETHER.

COULD LIFE BE BASED ON ONE OF THE OTHER FUNDAMENTAL FORCES INSTEAD?

FOR THIS TO BE POSSIBLE, ONE OF THE OTHER FORCES WOULD HAVE TO BE ABLE TO HOLD TOGETHER MATTER IN SOME SORT OF COMPLEX (LOW ENTROPY) ARRANGEMENT.

IF SO, LIFE WOULD BE VERY DIFFERENT FROM TERRESTRIAL LIFE.

HOW ARE THE FUNDAMENTAL FORCES RELATED TO LIFE?

COULD LIFE BE BASED ON ONE OF THE OTHER FUNDAMENTAL FORCES (NOT ELECTROMAGNETIC)? – PROBABLY NOT THE WEAK FORCE, BECAUSE IT

DOESN’T HOLD ANYTHING TOGETHER.– PROBABLY NOT THE GRAVITATIONAL FORCE

BECAUSE • IT IS SO WEAK THAT IT CAN ONLY HOLD TOGETHER VERY

LARGE OBJECTS LIKE PLANETS AND STARS. • THESE OBJECTS AREN'T PARTICULARLY COMPLEX OR

ORGANIZED. (THEY DON'T HAVE A PARTICULARLY LOW ENTROPY.)

• FOR INTERACTIONS BETWEEN SMALLER AMOUNTS OF MATTER, GRAVITY IS SO WEAK THAT WE CAN IGNORE IT.

– HOW ABOUT THE STRONG FORCE?

LIFE BASED ON THE STRONG FORCE?

THE STRONG FORCE HOLDS PROTONS AND NEUTRONS TOGETHER IN ATOMIC NUCLEI.

ORDINARY NUCLEI AREN’T VERY COMPLEX OR ORDERED, BUT…

NEUTRONS CAN FORM COMPLEX ARRANGEMENTS (HELD TOGETHER BY STRONG FORCE) ON THE SURFACE OF A NEUTRON STAR.

COULD THESE BE COMPLEX ENOUGH TO BE CONSIDERED LIFE??

LIFE BASED ON THE STRONG FORCE?

WE DON’T KNOW, BUT IF SO,– SIZE OF ORGANISMS ~ 0.00000000001 CM– STRONG INTERACTIONS OCCUR VERY

QUICKLY (VERY SHORT TIMESCALES) – THEREFORE LIFETIME OF INDIVIDUAL ORGANISM IS ~ 0.000000000000001 SEC

– COMMUNICATION VIA GAMMA RAYS?– HIGHLY RECOMMENDED SCIENCE

FICTION BOOK: “THE DRAGON’S EGG” BY ROBERT FORWARD

SEARCHING FOR LIFE IN OTHER SOLAR SYSTEMSWE WILL TAKE A CONSERVATIVE APPROACH. WE WILL

CONSIDER ONLY LIFE THAT IS BASED ON THE ELECTROMAGNETIC INTERACTION, i.e., ATOMS AND MOLECULES.

FURTHERMORE, WE WILL ONLY CONSIDER LIFE THAT USES CARBON-BASED CHEMISTRY AND USES WATER AS ITS LIQUID SOLVENT.

IGNORE POSSIBILITY OF “EXOTIC LIFE,” SUCH AS LIFE THAT USES A LIQUID SOLVENT OTHER THAN WATER, SILICON-BASED LIFE, OR LIFE BASED ON THE STRONG FORCE.

THEREFORE CONSIDER ONLY “EARTH-LIKE” PLANETS (OR LARGE MOONS) WITH LIQUID WATER.

SEARCHING FOR LIFE IN OTHER SOLAR SYSTEMS

WHY SUCH A CONSERVATIVE APPROACH?WE WILL BE MAKING ESTIMATES OF HOW

COMMON OR RARE LIFE MIGHT BE.WE JUST DON'T KNOW ENOUGH ABOUT

“EXOTIC LIFE” TO ESTIMATE WHETHER IT IS EVEN POSSIBLE, MUCH LESS HOW COMMON IT MIGHT BE.

IF EXOTIC LIFE CAN EXIST, THEN LIFE MAY EXIST IN A LARGER RANGE OF LOCATIONS AND BE MORE COMMON THAN WHAT WE WILL ESTIMATE.

PROPERTIES OF A PLANET THAT IS SUITABLE FOR LIFE

1. RELATIVELY LARGE ABUNDANCES OF CARBON, NITROGEN, AND OXYGEN (PLUS TRACE AMOUNTS OF HEAVIER ELEMENTS)

2. NOT NEAR A SITE OF COSMIC VIOLENCE3. ROCKY PLANET - SOLID SURFACE4. MASSIVE ENOUGH TO RETAIN A

REASONABLY DENSE ATMOSPHERE 5. CORRECT TEMPERATURE RANGE FOR LIQUID

WATER (SOLVENT)6. STABLE ENVIRONMENT FOR SEVERAL

BILLION YEARS (TIME NEEDED ON EARTH FOR “ADVANCED” LIFE FORMS TO EVOLVE)

ABUNDANCES OF ELEMENTS HYDROGEN AND HELIUM (BUT NO HEAVIER

ELEMENTS) ARE PRODUCED SHORTLY AFTER THE BIG BANG (DURING THE FIRST FEW MINUTES OF THE UNIVERSE).

HEAVIER ELEMENTS ARE PRODUCED VIA FUSION IN STARS (AND IN SUPERNOVA EXPLOSIONS ), AND RETURNED TO THE INTERSTELLAR MEDIUM VIA PLANETARY NEBULAE AND SUPERNOVAE.

HEAVIER ELEMENTS ARE INCORPORATED IN NEW STARS (AND THEIR PLANETARY SYSTEMS) FORMED FROM THE ENRICHED INTERSTELLAR MEDIUM.

ABUNDANCES OF ELEMENTS THEREFORE, PLANETARY SYSTEMS AROUND

YOUNGER STARS CONTAIN LARGER ABUNDANCES OF HEAVY ELEMENTS (ANYTHING HEAVIER THAN H AND He) THAN PLANETARY SYSTEMS OF OLDER STARS.

THUS PLANETS THAT CONTAIN ELEMENTS NECESSARY FOR LIFE ARE MORE LIKELY TO BE FOUND ORBITING YOUNGER STARS THAN OLDER STARS.

PLANETS MAY NOT EVEN BE ABLE TO FORM AROUND VERY OLD STARS WITH VERY LOW ABUNDANCES OF HEAVY ELEMENTS.

ABUNDANCES OF ELEMENTS POPULATION II STARS: OLD STARS, LOW

ABUNDANCES OF HEAVY ELEMENTS (0.1 – 0.5%)

POPULATION I STARS: YOUNGER STARS, HIGHER ABUNDANCES OF HEAVY ELEMENTS (1 - 2%)

PLANETS ORBITING POPULATON I STARS ARE MORE SUITABLE FOR LIFE – MORE HEAVY ELEMENTS

MOST STARS EXISTING TODAY (INCLUDING THE SUN) ARE POPULATION I STARS.

WHERE ARE POP I AND POP II STARS?

POPULATION I (PLANETS MAY BE SUITABLE CANDIDATES FOR LIFE):– DISKS OF SPIRAL GALAXIES, ESPECIALLY

IN SPIRAL ARMS– MOST IRREGULAR GALAXIES

POPULATION II (PLANETS ARE PROBABLY NOT SUITABLE CANDIDATES FOR LIFE):– NUCLEUS AND OUTER HALO OF SPIRAL

GALAXIES, PLUS GLOBULAR CLUSTERS– ELLIPTICAL GALAXIES

COSMIC VIOLENCE SOME ASTRONOMICAL ENVIRONMENTS WOULD

PROBABLY BE FATAL TO LIFE:– HIGH INCIDENCE OF GAMMA RAYS OR X-RAYS (HIGH

ENERGY PHOTONS) – FREQUENT STELLAR COLLISIONS OR NEAR-

COLLISIONS LOTS OF COMETARY IMPACTS LOCATIONS WHERE THIS IS A PROBLEM:

– NEAR GALACTIC CENTER (RADIATION FROM VICINITY OF CENTRAL BLACK HOLE, PLUS FREQUENT STELLAR COLLISIONS)

– NEAR SUPERNOVAE – NEAR ANY OTHER X-RAY AND GAMMA RAY SOURCE

ROCKY PLANETS

PROBABLY OCCUR MOST OF THE TIME AS LONG AS:

– THE ABUNDANCE OF HEAVY ELEMENTS IS HIGH ENOUGH TO MAKE ROCK, i.e., IN A SOLAR SYSTEM AROUND A POPULATION I STAR.

– THE PLANET IS IN THE INNER PART OF ITS SOLAR SYSTEM. (THEREFORE LIGHT GAS MOLECULES LIKE HYDROGEN AND HELIUM ARE MOVING FAST ENOUGH TO ESCAPE FROM ITS ATMOSPHERE, PREVENTING IT FROM BECOMING A GAS GIANT.)

ATMOSPHERE NEEDED TO KEEP WATER (OR OTHER LIQUID

SOLVENT) FROM BOILING AWAY INTO SPACE HELPS TO SPREAD HEAT AROUND, AVOIDING

TEMPERATURE EXTREMES MAY ALSO SUPPLY GASES FOR ORGANISMS TO

BREATHE MAY ALSO SUPPLY GASES NEEDED FOR CHEMICAL

REACTIONS INVOLVED WITH THE ORIGIN OF LIFE PLANET MUST BE MASSIVE ENOUGH TO RETAIN AN

ATMOSPHERE, i.e., ITS GRAVITY MUST BE SUFFICIENT TO PREVENT MOST GAS MOLECULES FROM ESCAPING. – RECALL THAT IN OUR SOLAR SYSTEM, MARS IS

TOO LIGHT.

RIGHT TEMPERATURE RANGE

MAINTAINED VIA A NEARLY CIRCULAR ORBIT AT THE RIGHT DISTANCE FROM ITS STAR FOR A TEMPERATURE ALLOWING LIQUID WATER (i.e., IN THE “HABITABLE ZONE”)

OR

PROVIDED BY A SOURCE OF INTERNAL HEAT (E.G., RADIOACTIVE DECAY, OR TIDAL FORCES AS WITH JUPITER’S MOONS IO AND EUROPA). THIS CAN HAPPEN EVEN IF THE PLANET OR MOON IS LOCATED FARTHER FROM ITS STAR.

HABITABLE ZONE SPHERICAL SHELL SURROUNDING STAR IN

WHICH ANY ORBITING PLANETS WILL HAVE THE RIGHT TEMPERATURE FOR LIQUID WATER

INNER EDGE OF ZONE IS WHERE AVERAGE TEMPERATURE = 100oC

OUTER EDGE OF ZONE IS WHERE AVERAGE TEMPERATURE = 0oC

WHERE IS THE HABITABLE ZONE FOR FOR OUR SUN?

OUR SUN’S HABITABLE ZONE INNER EDGE: ABOUT 0.85 - 0.95 AU FROM SUN OUTER EDGE: ROUGHLY 1.4 - 1.7 AU FROM SUN

– EXACT VALUES DEPENDS ON DETAILS OF GREENHOUSE EFFECT

HABITABLE ZONE MOVES OUTWARD WITH TIME, AS SUN BRIGHTENS SLIGHTLY– WHEN SOLAR SYSTEM FIRST FORMED, INNER EDGE

AT 0.65 – 0.80 AU AND OUTER EDGE AT 1.1 – 1.5 AU CONTINUOUSLY HABITABLE ZONE (FOR FIRST

FEW BILLION YEARS AFTER SOLAR SYSTEM FORMED)– INNER EDGE AT 0.85 TO 0.95 AU– OUTER EDGE AT 1.1 TO 1.5 AU

OUR SUN’S HABITABLE ZONE

WHERE ARE PLANETS RELATIVE TO SUN’S HABITABLE ZONE?

EARTH IS AT 1 AU – WITHIN CONTINUOUSLY HABITABLE ZONE (OBVIOUSLY!)

VENUS IS AT 0.72 AU – TOO CLOSE NOW, BUT MAY HAVE BEEN BARELY HABITABLE VERY EARLY IN ITS HISTORY.

MARS IS AT 1.52 AU – PROBABLY WITHIN HABITABLE ZONE NOW, BUT POSSIBLY NOT EARLIER IN ITS HISTORY.– BUT THE REAL PROBLEM IS THAT MARS IS TOO

LIGHT, SO IT LOST MOST OF ITS ATMOSPHERE.

PROPERTIES OF MAIN SEQUENCE STARS

SPECTRAL TYPE

BRIGHTNESS (SUN=1)

NUMBER OF STARS IN MW

PERCENT OF

TOTAL

O

B

A

F

G

K

M

100,000

500

10

2

0.9

0.2

0.005

80,000

360 MILLION

2.4 BILLION

12 BILLION

28 BILLION

60 BILLION

290 BILLION

0.00002%

0.09%

0.6%

3%

7%

15%

73%

COLOR

BLUE

BLUE

WHITE

YELLOW

YELLOW

ORANGE

RED

HABITABLE ZONES AROUND OTHER STARS

FOR BRIGHTER STARS:– HABITABLE ZONE IS FARTHER FROM STAR AND

LARGER IN EXTENT (E.G., 5 TO 20 AU FOR AN A-TYPE MAIN SEQUENCE STAR)

FOR FAINTER STARS:– HABITABLE ZONE IS CLOSER TO STAR AND SMALLER

IN EXTENT (E.G., 0.02 TO 0.06 AU FOR AN M-TYPE MAIN SEQUENCE STAR)

– HABITABLE ZONE MAY BE SO SMALL THAT IT IS UNLIKELY THAT ANY PLANETS ARE FOUND WITHIN IT

– IF PLANET IS TOO CLOSE TO STAR, OTHER POSSIBLE PROBLEMS INCLUDE:

• SOLAR FLARES • PLANET’S ROTATION MAY BE TIDALLY LOCKED (MIGHT BE

OK IF ATMOSPHERE CAN SPREAD HEAT AROUND ENOUGH)

STABLE ENVIRONMENT STAR MUST NOT CHANGE TOO MUCH IN

TEMPERATURE OR BRIGHTNESS FOR SEVERAL BILLION YEARS

THIS REQUIRES A MAIN SEQUENCE STAR THAT IS COOLER/REDDER/FAINTER THAN MID-F SPECTRAL TYPE – MAIN SEQUENCE LIFETIME IS TOO SHORT FOR

HOTTER/BLUER/BRIGHTER STARS– THIS REQUIREMENT ELIMINATES ONLY A FEW

PERCENT OF ALL MAIN SEQUENCE STARS

PROPERTIES OF MAIN SEQUENCE STARS

SPECT. TYPE

BRIGHTNESS SUN=1

LIFETIME (YEARS)

# OF STARS (IN MW)

PERCENT OF TOTAL

O

B

A

F

G

K

M

100,000

500

10

2

0.9

0.2

0.005

5 MILLION

10 MILLION

500 MILLION

1 BILLION

10 BILLION

100 BILLION

1 TRILLION

80,000

360 MILLION

2.4 BILLION

12 BILLION

28 BILLION

60 BILLION

290 BILLION

0.00002%

0.09%

0.6%

3%

7%

15%

73%

COLOR

BLUE

BLUE

WHITE

YELLOW

YELLOW

ORANGE

RED