1 00:00:02,502 --> 00:00:13,079 ANDROMEDAS FATHER! 2 00:00:13,179 --> 00:00:24,691 JAMES: WELCOME TO STAR GAZERS. 3 00:00:24,791 --> 00:00:28,461 I'M JAMES ALBURY, DIRECTOR OF THE KIKA SILVA PLA PLANETARIUM IN GAINESVILLE FLORIDA. 4 00:00:28,561 --> 00:00:31,464 DEAN: AND I'M DEAN REGAS, ASTRONOMER FROM THE CINCINNATI 5 00:00:31,564 --> 00:00:32,832 OBSERVATORY. 6 00:00:32,932 --> 00:00:35,368 WE'RE HERE TO HELP YOU FIND YOUR WAY AROUND THE NIGHT SKY. 7 00:00:35,468 --> 00:00:40,340 THIS WEEK, WE'RE GOING TO TALK ABOUT A CONSTELLATION THATS PART OF AN ANCIENT CELESTIAL STORY. 8 00:00:40,440 --> 00:00:43,109 JAMES: AND MORE EXCITINGLY, ONE OF IT'S STARS HELPED 9 00:00:43,209 --> 00:00:47,981 ASTRONOMERS DETERMINE THE SIZE AND SHAPE OF OUR OWN GALAXY AND THE DISTANCES TO NEARBY 10 00:00:48,081 --> 00:00:49,049 GALAXIES. 11 00:00:49,149 --> 00:00:50,750 WONDERING WHAT WERE TALKING ABOUT? 12 00:00:50,850 --> 00:00:51,985 LETS SHOW YOU! 13 00:00:52,085 --> 00:00:55,188 JAMES: OK, WE HAVE OUR SKIES SET FOR AN HOUR AFTER 14 00:00:55,288 --> 00:00:58,324 SUNSET, ANY NIGHT THIS WEEK, FACING NORTH. 15 00:00:58,425 --> 00:01:02,495 OFF TO THE NORTHEAST YOU'LL SEE THE FAMILIAR W-SHAPED PATTERN OF CASSIOPEIA THE QUEEN. 16 00:01:02,595 --> 00:01:09,035 THE STARS THAT MARK THIS CONSTELLATION, STARTING FROM THE TOP DOWN ARE CAPH, SHEDAR, TSIH, 17 00:01:09,135 --> 00:01:11,171 RUCHBAH AND SEGIN. 18 00:01:11,271 --> 00:01:14,274 DEAN: IF YOU DRAW A STRAIGHT LINE FROM SHEDAR TO 19 00:01:14,374 --> 00:01:18,511 CAPH AND KEEP ON GOING, YOU'LL RUN SMACK DAB INTO A CONSTELLATION THAT LOOKS 20 00:01:18,611 --> 00:01:20,547 LIKE AN UPSIDE-DOWN HOUSE. 21 00:01:20,647 --> 00:01:22,582 THIS IS CEPHEUS THE KING. 22 00:01:22,682 --> 00:01:26,119 CEPHEUS WAS THE HUSBAND OF CASSIOPEIA AND FATHER OF ANDROMEDA. 23 00:01:26,219 --> 00:01:29,055 JAMES: THE BRIGHTEST STAR IN CEPHEUS IS ALDERAMIN 24 00:01:29,155 --> 00:01:31,925 AND ITS 49 LIGHT YEARS AWAY FROM US. 25 00:01:32,025 --> 00:01:37,163 IT'S BAYER DESIGNATION IS ALPHA CEPHEII, SO NAMED BY GERMAN ASTRONOMER JOHANN BAYER, WHO 26 00:01:37,263 --> 00:01:41,601 NAMED THE STARS WITH A GREEK LETTER (BASED ON THEIR BRIGHTNESS) AND THE LATINIZED NAME 27 00:01:41,701 --> 00:01:43,403 OF THE CONSTELLATION. 28 00:01:43,503 --> 00:01:46,539 BEING THE BRIGHTEST STAR IN CEPHEUS, IT WAS NAMED ALPHA CEPHEII. 29 00:01:46,639 --> 00:01:49,576 DEAN: ALDERAMIN LIES VERY CLOSE TO A REGION OF THE 30 00:01:49,676 --> 00:01:52,212 NORTHERN SKY CALLED THE PRECESSION CIRCLE. 31 00:01:52,312 --> 00:01:58,651 OVER A PERIOD OF 26,000 YEARS, EARTHS ROTATIONAL AXIS PASSES THROUGH SEVERAL CONSTELLATIONS, 32 00:01:58,751 --> 00:02:01,321 TRACING A GIANT CIRCLE IN THE SKY. 33 00:02:01,421 --> 00:02:06,426 RIGHT NOW, OUR ROTATIONAL AXIS IS POINTING TOWARD POLARIS; OUR CURRENT NORTH STAR. 34 00:02:06,526 --> 00:02:10,663 HOWEVER IN 7500 AD, ALDERAMIN WILL BE OUR NORTH STAR. 35 00:02:10,763 --> 00:02:13,600 JAMES: TRAVELING COUNTER CLOCKWISE FROM ALDERAMIN, 36 00:02:13,700 --> 00:02:17,337 WE HAVE ALFIRK, ALSO KNOWN AS BETA CEPHEII. 37 00:02:17,437 --> 00:02:22,108 ALFIRK IS A MULTIPLE STAR SYSTEM APPROXIMATELY 690 LIGHT YEARS FROM EARTH. 38 00:02:22,208 --> 00:02:25,979 ALFIRK WILL BE OUR NORTH STAR BETWEEN 5200 AD AND 7500 AD. 39 00:02:26,079 --> 00:02:28,982 DEAN: THE NEXT STAR IN CEPHEUS IS ERRAI; 40 00:02:29,082 --> 00:02:31,251 ALSO KNOWN AS GAMMA CEPHEII. 41 00:02:31,351 --> 00:02:36,022 ERRAI MARKS THE POINT ON THE ROOF OF THIS HOUSE-SHAPED CONSTELLATION AND IS A BINARY 42 00:02:36,122 --> 00:02:39,492 STAR SYSTEM APPROXIMATELY 45 LIGHT YEARS AWAY. 43 00:02:39,592 --> 00:02:43,463 ERRAI WILL BECOME OUR NORTH STAR IN LESS THAN A THOUSAND YEARS, 44 00:02:43,563 --> 00:02:47,133 AND IT WILL RETAIN THE TITLE OF NORTH STAR FOR OVER 2000 MORE. 45 00:02:47,233 --> 00:02:52,572 IN 5200 AD IT WILL HAVE TO RELINQUISH THE TITLE TO BOTH ALFIRK AND 46 00:02:52,672 --> 00:02:55,141 THE NEXT STAR IN CEPHEUS, IOTA CEPHEII. 47 00:02:55,241 --> 00:02:58,545 JAMES: IN 6000 AD, THE EARTHS AXIS WILL POINT SMACK 48 00:02:58,645 --> 00:03:03,650 DAB IN THE MIDDLE - BETWEEN ALFIRK AND IOTA CEPHEII; AND FOR ALMOST 2000 YEARS, 49 00:03:03,750 --> 00:03:07,487 THEY WILL SEEM TO PERFORM A NIGHTLY WALTZ AROUND OUR NORTH CELESTIAL POLE. 50 00:03:07,587 --> 00:03:10,557 DEAN: IOTA CEPHEII IS A SINGLE STAR, APPROXIMATELY 51 00:03:10,657 --> 00:03:12,992 206 LIGHT YEARS AWAY FROM US. 52 00:03:13,092 --> 00:03:17,463 ITS OVER TWICE THE MASS AND OVER 57 TIMES AS BRIGHT AS OUR SUN. 53 00:03:17,564 --> 00:03:20,633 JAMES: THE FIFTH STAR IN CEPHEUS IS ZETA CEPHEII; 54 00:03:20,733 --> 00:03:25,438 AN ORANGE SUPERGIANT STAR OVER 830 LIGHT YEARS AWAY AND OVER 55 00:03:25,538 --> 00:03:27,774 8 TIMES THE MASS OF OUR SUN. 56 00:03:27,874 --> 00:03:31,844 THE MASS VALUE IS IMPORTANT, BECAUSE ITS VERY LIKELY, FROM WHAT WE KNOW ABOUT THE PROCESSES 57 00:03:31,945 --> 00:03:35,682 THAT HAPPEN WITHIN A STAR, THAT ZETA CEPHEII HAS A ENOUGH MASS TO ULTIMATELY 58 00:03:35,782 --> 00:03:38,451 GO SUPERNOVA, PRODUCING A VERY DENSE WHITE DWARF 59 00:03:38,551 --> 00:03:39,586 AS A RESULT. 60 00:03:39,686 --> 00:03:41,387 DEAN: THE LAST STAR WE'LL TALK ABOUT IS ONE OF 61 00:03:41,487 --> 00:03:42,789 MY FAVORITES. 62 00:03:42,889 --> 00:03:45,658 IT'S DELTA CEPHEII AND ITS JUST UP AND TO THE RIGHT OF ZETA. 63 00:03:45,758 --> 00:03:50,597 THIS STAR IS SPECIAL BECAUSE ITS THE PROTOTYPE FOR A CLASS OF STARS THAT ASTRONOMERS CALL 64 00:03:50,697 --> 00:03:54,100 CEPHEID VARIABLES, AND ITS BECAUSE OF THIS STAR THAT WE KNOW 65 00:03:54,200 --> 00:03:56,369 THE DISTANCES TO NEARBY GALAXIES. 66 00:03:56,469 --> 00:04:00,306 JAMES: IN 1784 A YOUNG ENGLISH ASTRONOMER NAMED JOHN 67 00:04:00,406 --> 00:04:04,844 GOODRICKE BEGAN OBSERVING DELTA CEPHEII AND NOTICED THAT IT VARIED IN BRIGHTNESS AT REGULAR 68 00:04:04,944 --> 00:04:06,246 INTERVALS. 69 00:04:06,346 --> 00:04:08,081 THIS DISCOVERY LAID THE GROUND WORK FOR MEASURING DISTANCES 70 00:04:08,181 --> 00:04:09,415 IN THE UNIVERSE. 71 00:04:09,515 --> 00:04:12,018 DEAN: IN 1908, ASTRONOMER HENRIETTA LEVITT WAS STUDYING 72 00:04:12,118 --> 00:04:16,556 THOUSANDS OF VARIABLE STARS IN THE MAGELLANIC CLOUDS AND SHE NOTICED THAT MANY STARS WERE 73 00:04:16,656 --> 00:04:18,491 FOUND TO HAVE THIS SAME RELATIONSHIP. 74 00:04:18,591 --> 00:04:20,660 JAMES: ONCE THE PULSATION PERIOD FOR A PARTICULAR 75 00:04:20,760 --> 00:04:24,397 CEPHEID VARIABLE WAS DETERMINED, ASTRONOMERS COULD GET AN ACCURATE MEASUREMENT OF THE STARS 76 00:04:24,497 --> 00:04:27,834 DISTANCE, BY COMPARING THE STARS KNOWN LUMINOSITY TO ITS OBSERVED BRIGHTNESS. 77 00:04:27,934 --> 00:04:30,570 DEAN: THIS RELATIONSHIP WAS SO STRONG THAT IT ALLOWED 78 00:04:30,670 --> 00:04:34,040 ASTRONOMERS TO ESTABLISH THE SIZE AND SHAPE OF OUR GALAXY. 79 00:04:34,140 --> 00:04:35,742 JAMES: ISNT ASTRONOMY WONDERFUL? 80 00:04:35,842 --> 00:04:37,043 AND ITS ALL WAITING FOR YOU WHEN YOU 81 00:04:37,143 --> 00:04:41,143 BOTH: KEEP LOOKING UP!