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!