ASTRONOMICAL DISTANCES

DEAN:
HEY THERE STAR GAZERS.

I'M DEAN REGAS, ASTRONOMER FOR THE CINCINNATI
OBSERVATORY.

JAMES:
AND I'M JAMES ALBURY, DIRECTOR OF THE KIKA

SILVA PLA PLANETARIUM
IN GAINESVILLE, FLORIDA.

WE RE HERE TO HELP YOU FIND YOUR WAY AROUND
THE SKY TONIGHT.

HEY DEAN, HUMOR ME.

IF YOU WANT TO DESCRIBE YOUR HEIGHT, WHAT
UNITS OF MEASURE WOULD

YOU USE?

DEAN:
I'D USE FEET AND INCHES.

JAMES:
AND IF WE WANT TO MEASURE THE DISTANCE TO

THE MOON WHAT DO WE USE?

DEAN:
I COULD USE FEET AND INCHES, BUT USING MILES

MAKES MORE SENSE.

JAMES:
HOW ABOUT THE DISTANCE TO STARS?

DEAN:
AH, WE USE LIGHT YEARS.

DISTANCES IN SPACE ARE SO

WELL

ASTRONOMICAL THAT IT S HARD TO WRAP OUR
BRAINS AROUND THEM.

SO WE CREATED NEW UNITS OF MEASUREMENT TO
TAKE US AROUND THE SOLAR SYSTEM AND THROUGH

INTERSTELLAR SPACE.

JAMES:
SO, LET'S TAKE YOU TO THE MOON,JUPITER , AND

BEYOND!

JAMES:
OKAY, WE HAVE OUR SKY SET UP FOR THE EVENING

OF MAY 26TH, ABOUT 10:30PM AND WE RE FACING
SOUTHEAST.

DEAN:
EVERY NIGHT THIS WEEK YOU WILL SEE THE WAXING

MOON IN THE NIGHT SKY BUT ON THIS NIGHT, THE
MOON WILL BE A WAXING GIBBOUS AND APPEAR AT

THE FEET OF THE CONSTELLATION VIRGO.

LET'S ZOOM IN ON THE MOON AND GET OUT OUR
TAPE-MEASURE.

DEAN:
ON AVERAGE, THE MOON IS ABOUT 239,000 MILES

FROM THE EARTH.

WE CAN FIND OUT THE PRECISE DISTANCE TO THE
MOON ANY TIME BY BOUNCING LASERS OFF THE REFLECTORS

SET UP BY THE APOLLO ASTRONAUTS.

JAMES:
NEIL ARMSTRONG, BUZZ ALDRIN AND COMPANY TOOK

THREE DAYS TO FLY THE 239,000 MILES TO THE
MOON - AND THREE DAYS TO FLY BACK.

JAMES:
OUR NEXT STOP

IS JUPITER.

THE LARGEST PLANET IS EASY TO FIND IN THE
NIGHT SKY ALL THIS WEEK.

LOOK SOUTHEAST AFTER DARK AND YOU CAN T
MISS IT.

JUPITER IS SOUP-IT-TER BRIGHT!

DEAN:
SOUP-IT-TER?

I LIKE IT!

ANYWAY, JUPITER IS BRIGHTER THAN ANY OTHER
STAR IN THE NIGHTTIME SKY.

ONLY THE PLANET VENUS (AND ON RARE OCCASIONS,
MARS)

CAN BE MORE DAZZLING.

JAMES:
THIS IS A GOOD WEEK TO AIM A TELESCOPE AT

JUPITER WHERE YOU CAN SEE SEVERAL MOONS AROUND
IT, SOME STRIPES ON IT, AND MAYBE THE GREAT

RED SPOT:
THE GIANT HURRICANE ON THE PLANET.

JAMES:
THIS WEEK JUPITER IS ABOUT 410 MILLION MILES

AWAY.

NOW, THAT NUMBER IS HARD TO PICTURE, SO WHEN
WE'RE TALKING ABOUT DISTANCES IN

THE SOLAR SYSTEM ASTRONOMERS USE
A DIFFERENT UNIT OF MEASURE -

THE ASTRONOMICAL UNIT OR A.U...

ONE A.U. IS THE AVERAGE DISTANCE BETWEEN THE
SUN AND EARTH,

SO WE'RE ABOUT
1 A.U.

FROM THE SUN.

IN MILES, THAT'S 93,000,000 MILES.

DEAN:
SO SINCE JUPITER IS 410 MILLION MILES AWAY

IT IS ALSO ABOUT 4.4 A.U.S FROM US.

A.U.'S WORK GREAT WITHIN THE
SOLAR SYSTEM.

FOR EXAMPLE, WE COULD SAY SATURN IS ABOUT
10 A.U.'S FROM THE SUN, NEPTUNE IS ABOUT 30

A.U.'S FROM THE SUN AND VOYAGER 1 --
OUR FARTHEST FLUNG SPACECRAFT --

IS A WHOPPING 140 A.U.'S FROM THE SUN!

JAMES:
YOU MAY NOTICE A LITTLE STAR NEXT TO JUPITER.

THAT IS ONE OF MY FAVORITE STARS TO SAY OUT
LOUD AND FAST.

IT S CALLED ZUBENELGENUBI AND IT S THE
SECOND BRIGHTEST STAR IN THE CONSTELLATION

LIBRA
THE SCALES.

DEAN:
ZUBENELGENUBI IS ABOUT 447 TRILLION MILES

FROM EARTH, OR ALMOST
5 MILLION A.U.'S.

WE COULD MEASURE THE DISTANCE TO ZUBENELGENUBI
IN MILLIMETERS IF WE WANTED TO, BUT THOSE

NUMBERS LOSE ALL MEANING.

JAMES:
ASTRONOMERS USE LIGHT YEARS AS THEIR UNIT

OF CHOICE FOR MEASURING INTERSTELLAR DISTANCES.

A LIGHT YEAR IS THE DISTANCE LIGHT TRAVELS
IN A YEAR -- ROUGHLY 5.8 TRILLION MILES.

SO A LIGHT YEAR IS A DISTANCE LIKE A MILE
OR AN A.U..

DEAN:
AND ZUBENELGENUBI IS A WHOPPING 77 LIGHT YEARS

FROM EARTH.

IT'S BY NO MEANS THE FARTHEST STAR YOU CAN
SEE WITH THE NAKED EYE.

THAT HONOR MOST LIKELY GOES TO DENEB - THE
TAIL STAR OF CYGNUS THE SWAN - WHO YOU'LL

BE LEARNING MORE ABOUT THIS SUMMER.

DENEB IS OVER 3000 LIGHT YEARS AWAY.

THAT MEANS THE LIGHT YOU SEE FROM DENEB LEFT
IT AROUND 1000 BC AND IS ONLY NOW GETTING

TO YOUR EYES.

DEAN:
SO THIS WEEK GET OUTSIDE TO SEE THE MOON AT

239,000 MILES AWAY.

JAMES:
JUPITER FROM 4.4 A.U.'S AWAY.

DEAN:
AND ZUBENELGENUBI AT 77 LIGHT YEARS AWAY.

AND THERE IS ONE MORE THING

JAMES:
YESSSS?

DEAN:
I KNOW YOU LL LIKE THIS JAMES BUT ON THE

NIGHT OF MAY 27TH, THE MOON WILL COZY UP TO
JUPITER AND ZUBENELGENUBI AND MAKE A COOL

JAMES:
CONJUNCTION!

DEAN:
IT S ALL THERE WHEN YOU

ALL:
KEEP LOOKING UP!