JAMES:
THIS WEEK, WE RE GOING TO TALK ABOUT A CONSTELLATION

THAT S PART OF AN ANCIENT CELESTIAL STORY.

DEAN:
AND ONE OF ITS STARS HELPED ASTRONOMERS DETERMINE

THE SIZE AND SHAPE OF OUR OWN GALAXY AND THE
DISTANCES TO NEARBY GALAXIES.

JAMES:
OK, WE HAVE OUR SKIES SET FOR AN HOUR AFTER

SUNSET, ANY NIGHT THIS WEEK, FACING
NORTHEAST.

YOU LL SEE THE
W-SHAPED PATTERN OF CASSIOPEIA.

DRAW A STRAIGHT LINE FROM THE TWO STARS AT
THE TOP OF THE W AND

YOU LL RUN SMACK DAB INTO CEPHEUS THE KING.

HE LOOKS LIKE AN
UPSIDE-DOWN HOUSE.

DEAN:
STARTING WITH THE BRIGHTEST STAR AND TRAVELING

COUNTER CLOCKWISE, WE HAVE ALDERAMIN, ALFIRK,
ERRAI, IOTA CEPHEII AND ZETA CEPHEII.

JAMES:
RIGHT NEXT TO ZETA CEPHEII WE HAVE DELTA CEPHEII

AND IT WAS DISCOVERED THAT
THIS STAR VARIED IN BRIGHTNESS

AT REGULAR INTERVALS.

SO MANY STARS SHOWED THIS SAME PATTERN,
THAT IT LAID THE GROUND WORK FOR MEASURING

DISTANCES
IN THE UNIVERSE.

BOTH: KEEP LOOKING UP!