JAMES: WELCOME TO STAR GAZERS. I'M JAMES ALBURY,
DIRECTOR OF THE KIKA SILVA PLA PLANETARIUM

IN GAINESVILLE, FLORIDA.

DEAN: AND I'M DEAN REGAS, ASTRONOMER FROM
THE CINCINNATI OBSERVATORY.

JAMES: LAST WEEK, DEAN AND I TALKED ABOUT
THE ROCKY PLANETS AND OF COURSE THAT PROMPTED

THE FEDERATION OF GAS GIANT PLANETS TO SEND
US A STRONGLY WORDED LETTER DEMANDING EQUAL

TIME. SO

DEAN: WE DEVOTED THIS WEEK'S SHOW TO THE LARGEST
OF THE GAS GIANT PLANETS, SPECIFICALLY THE

KING OF THE SOLAR SYSTEM, JUPITER.

JAMES: IF YOU'RE A PERSON WHO LIKES TO DO
YOUR PLANET WATCHING BEFORE SUNRISE, JUPITER

IS IN A GREAT POSITION FOR VIEWING RIGHT NOW.
SO LET'S GET JOVIAN WITH JUPITER.

DEAN: OK, WE HAVE OUR SKY SET TO AN HOUR BEFORE
SUNRISE ANY NIGHT THIS WEEK, FACING SOUTH.

HIGH IN THE SKY, YOULL SEE TWO BRIGHT LIGHTS
IN THE CONSTELLATION VIRGO THE MAIDEN. THE

ONE THATS TWINKLING IS THE BLUE GIANT STAR
SPICA. THE ONE THAT ISNT TWINKLING IS OUR

FRIEND, JUPITER.

JAMES: THROUGH EVEN A MODEST TELESCOPE, JUPITER
SHOWS ITSELF AS A DISK WITH DARK BANDING ACROSS

ITS SURFACE. AND IF YOUR SKIES ARE PARTICULARLY
STEADY, AND YOUR TIMING IS RIGHT, YOU MAY

CATCH A GLIMPSE OF THE GREAT RED SPOT.

DEAN: AT CURRENT COUNT, 67 MOONS SURROUND
JUPITER AND FOUR OF THEM ARE CLOSE TO THE

SAME SIZE OR LARGER THAN OUR OWN MOON. THEYRE
NAMED, IO, EUROPA, GANYMEDE AND CALLISTO;

AND YOU CAN SEE THEM CHANGE POSITION EVERY
NIGHT, THROUGH EVEN A SMALL TELESCOPE.

JAMES: JUPITER IS NOT ONLY THE LARGEST PLANET
IN OUR SOLAR SYSTEM, BUT ITS GRAVITY IS SO

STRONG THAT IT'S SOMETIMES REFERRED TO AS
THE SOLAR SYSTEM'S VACUUM CLEANER.

DEAN: JUPITER'S GRAVITY ATTRACTS NEARBY ASTEROIDS
AND OTHER SMALL SOLAR SYSTEM BODIES, AND IT

HAS BEEN KNOWN TO DRAMATICALLY CHANGE THE
ORBITS OF AN INBOUND COMET, WHICH CAN SHORTEN

OR LENGTHEN THE AMOUNT OF TIME IT TAKES FOR
THE COMET TO ORBIT THE SUN.

JAMES: IN JULY 1994, FRAGMENTS OF COMET SHOEMAKER-LEVY
9 COLLIDED WITH JUPITER, PROVIDING THE FIRST

DIRECT OBSERVATION OF A COLLISION BETWEEN
TWO SOLAR SYSTEM OBJECTS.

DEAN: THE PLANET JUPITER HAS BEEN OBSERVED
IN THE SKY SINCE ANTIQUITY. THE ANCIENT ROMANS

NAMED IT AFTER THE KING OF THEIR GODS, WHOM
THE GREEKS REFERRED TO AS ZEUS.

JAMES: BABYLONIAN ASTRONOMERS HAVE RECORDS
OF JUPITER DATING BACK TO THE 7TH CENTURY

B.C. IN HIS BOOK THE ALMAGEST, GREEK ASTRONOMER
CLAUDIUS PTOLEMY USED JUPITER'S MOTION WITH

RESPECT TO THE EARTH TO REFINE HIS EARTH-CENTERED
MODEL OF THE SOLAR SYSTEM.

DEAN: BY DOING THIS, PTOLEMY SHOWED THAT JUPITER
TOOK ALMOST 12 YEARS TO MAKE A COMPLETE CIRCUIT

OF THE SKY, WHICH WE NOW KNOW AS THE AMOUNT
OF TIME IT TAKES JUPITER TO ORBIT THE SUN.

JAMES: IN 1610, ITALIAN ASTRONOMER GALILEO
GALILEI STUDIED JUPITER USING A TELESCOPE

AND IS CREDITED WITH DISCOVERING THE FOUR
LARGEST MOONS OF JUPITER; IO, EUROPA, GANYMEDE

AND CALLISTO. THE MOTIONS OF THESE MOONS AROUND
JUPITER PROVIDED GALILEO WITH AN EXAMPLE SUPPORTING

NICHOLAS COPERNICUS' VIEW OF A SUN-CENTERED
SOLAR SYSTEM, BECAUSE IF YOU LOOK AT JUPITER

AND ITS MOONS, THEY DO LOOK LIKE A MINIATURE
VERSION OF OUR SOLAR SYSTEM.

DEAN: ASTRONOMERS GIOVANNI CASSINI AND ROBERT
HOOKE BOTH NOTICED A LARGE RED SPOT ON JUPITER

DURING THEIR TELESCOPIC OBSERVATIONS IN THE
1660'S. THIS SPOT, AFFECTIONATELY CALLED THE

GREAT RED SPOT, IS SO LARGE THAT YOU COULD
FIT TWO EARTHS INSIDE IT.

DEAN: JUPITER IS ENORMOUS. IF JUPITER WERE
HOLLOW, YOU COULD FIT OVER 1000 EARTHS INSIDE

IT, AND IT HAS OVER 120 TIMES THE SURFACE
AREA OF THE EARTH. IF JUPITER WERE THE SIZE

OF A BASKETBALL, EARTH WOULD BE ABOUT THE
SIZE OF A SMALL MARBLE.

JAMES: JUPITER ALSO SPINS VERY FAST. ITS DAY
IS ONLY 9.8 HOURS. WHICH MEANS THAT WHEN JUPITER

RISES AT SUNSET DURING THE WINTER MONTHS (WHEN
THE SKY IS DARK FOR MORE THAN 12 HOURS), IN

THE COURSE OF ONLY ONE NIGHT, YOU CAN ACTUALLY
SEE THE ENTIRE SURFACE OF THE PLANET.

DEAN: THIS RAPID SPINNING HAS CAUSED JUPITER
TO TAKE ON AN M & M SHAPE AND BECAUSE JUPITER

IS NOT A SOLID BODY, JUPITER'S ATMOSPHERE
ACTUALLY SPINS FASTER AT THE EQUATOR THAN

IT DOES AT THE POLES, MAKING THE CLOUDS FORM
THE STRIPES WE'VE COME TO KNOW AND LOVE.

DEAN: SO, GET OUTSIDE AND GAZE UPON THE GAS
GIANT PLANET JUPITER THIS WEEK.

JAMES: IT'S EASY TO DO WHEN YOU

BOTH: KEEP LOOKING UP!