MEASURING THE COSMOS
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: 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 MILES MAKES
A LOT MORE SENSE.
JAMES:
HOW ABOUT THE DISTANCE TO STARS?
DEAN:
AH, WE USE LIGHT YEARS.
DISTANCES IN SPACE ARE SO…
WELL…
ASTRONOMICAL THAT ITS HARD TO WRAP OUR BRAINS
AROUND THEM.
SO WE CREATED NEW UNITS OF MEASURE TO TAKE
US AROUND THE SOLAR SYSTEM AND THROUGH INTERSTELLAR
SPACE.
JAMES:
SO, LET'S TAKE YOU TO THE MOON, JUPITER, SATURN,
AND BEYOND!
JAMES:
OKAY, WE HAVE OUR SKY SET UP FOR THE NIGHT
OF THURSDAY JULY 11 AT 10:30 PM FACING SOUTH.
THE MOON IS IN ITS WAXING GIBBOUS PHASE - MEANING
IT WILL
SOON BE A FULL MOON.
DEAN:
EVERY DAY THE MOON WILL SHIFT FARTHER
TO THE EAST.
HERE IS THE MOON ON JULY 12TH…
AND JULY 13TH.
LET'S FLY UP THERE
AND TAKE OUR TAPE MEASURES WITH US.
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.
DEAN:
BACK ON EARTH, WHATS THAT BRIGHT LIGHT NEXT
TO THE MOON ON
JULY 13TH?
JAMES:
THAT IS THE GIANT PLANET JUPITER AND IT IS
RELATIVELY CLOSE TO US RIGHT NOW.
DEAN:
RELATIVELY CLOSE.
IT MAY LOOK LIKE ITS CLOSE TO THE MOON BUT
IT IS MUCH, MUCH FARTHER.
WHILE THE MOON IS ABOUT 239,000 MILES AWAY,
JUPITER IS
A WHOPPING 409 MILLION MILES AWAY!
JAMES:
AS THE NIGHT GOES ON WE GET CLOSER TO 11:30PM,
EVERYTHING HAS SHIFTED TO THE RIGHT.
AND ANOTHER PLANET IS GETTING HIGHER IN THE
SKY.
THIS IS SATURN.
DEAN:
SATURN IS JUST THE MOST AMAZING SIGHT TO SEE
IN A TELESCOPE.
YOU CAN SEE THE PLANET, THE RINGS, THE SHADOW
OF THE RINGS, THE MOONS…
JAMES:
CALM DOWN DEAN…
I KNOW SATURNS YOUR FAVORITE PLANET BUT LET'S
DO SOME MEASURING HERE.
JAMES:
THIS WEEK SATURN IS ABOUT 837 MILLION MILES
AWAY.
NOW THAT NUMBER IS HARD TO WRAP OUR BRAINS
AROUND, SO WHEN WERE TALKING ABOUT DISTANCES
IN THE SOLAR SYSTEM ASTRONOMERS USE A DIFFERENT
UNIT OF MEASUREMENT -
THE ASTRONOMICAL UNIT OR A.U.
ONE A.U. IS THE AVERAGE DISTANCE BETWEEN THE
SUN AND EARTH,
SO WERE ABOUT 1 A.U.
FROM THE SUN.
IN MILES THATS ABOUT 93,000,000 MILES.
DEAN:
SINCE SATURN IS ABOUT 837 MILLION MILES AWAY
IT IS ALSO ABOUT 9 AU'S FROM US.
AU'S WORK GREAT WITHIN THE SOLAR SYSTEM.
FOR EXAMPLE, WE COULD SAY JUPITER IS ABOUT
5 AU'S FROM THE SUN, NEPTUNE IS ABOUT
30 AU'S FROM THE SUN AND VOYAGER 1 -
OUR FARTHEST FLUNG SPACECRAFT IS A WHOPPING
120 AU'S FROM THE SUN!
JAMES:
NOW WHAT ABOUT THAT OTHER STAR - THE RED ONE
TO THE RIGHT OF JUPITER?
DEAN:
THAT'S THE STAR ANTARES IN THE CONSTELLATION
SCORPIUS THE SCORPION.
RED GIANT STARS LIKE ANTARES ARE HUMONGOUS
AND UNBELIEVABLY FAR.
JAMES:
LET'S CLOSE IN ON ANTARES AND MEASURE ITS
SIZE AND DISTANCE.
DEAN:
ANTARES IS ABOUT 3.6 QUADRILLION MILES FROM
EARTH, OR 39 MILLION AU'S.
WE COULD MEASURE THE DISTANCE TO ANTARES IN
MILLIMETERS IF WE WANTED TO, BUT THOSE NUMBERS
LOSE ALL MEANING FOR US.
JAMES:
ASTRONOMERS USE LIGHT YEARS AS THEIR UNIT
OF CHOICE FOR MEASURING INTERSTELLAR SPACE.
A LIGHT YEAR IS THE DISTANCE LIGHT TRAVELS
IN A YEAR - ROUGHLY 5.8 TRILLION MILES.
THEREFORE, ANTARES
IS A WHOPPING 620 LIGHT YEARS FROM EARTH.
DEAN:
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.
JAMES:
DENEB IS OVER 3000 LIGHT YEARS AWAY.
THAT MEANS THE LIGHT YOU SEE LEFT DENEB AROUND
1000 BC.
DEAN:
SO SEE THE MOON AT 239,000 MILES AWAY.
JAMES:
SATURN FROM 9 AU'S AWAY.
DEAN:
AND ANTARES AT 620 LIGHT YEARS AWAY.
BOTH: KEEP LOOKING UP!
