WPBT2's Star Gazers

Episode #14-39 "I See a Pattern Here"
Air Dates September 29, 2014 - October 5, 2014


FIVE MINUTE EPISODE SCRIPT
DEAN: WELCOME TO STAR GAZERS. I'M DEAN REGAS, ASTRONOMER FROM THE CINCINNATI OBSERVATORY.

JAMES: AND I'M JAMES ALBURY, DIRECTOR OF THE KIKA SILVA PLA PLANETARIUM IN GAINESVILLE FLORIDA. NEXT WEEK WE GET TO EXPERIENCE THE 2ND TOTAL LUNAR ECLIPSE OF THE 2014-2015 TETRAD.

DEAN:  YOU MIGHT BE ASKING YOURSELF, WHAT'S A TETRAD?. WELL, THEY'RE VERY RARE AND IN THIS WEEK'S EPISODE WE'LL TELL YOU WHY.

JAMES:  WELL ALSO GIVE YOU THE LOW DOWN ON THE  OCTOBER 8TH, LUNAR ECLIPSE.  LET'S SHOW YOU!

JAMES:  HERE'S HOW ECLIPSES WORK. CELESTIAL BODIES  CAST TWO SHADOWS; A DARKER INNER SHADOW CALLED THE UMBRA AND A LIGHTER OUTER SHADOW CALLED THE PENUMBRA. YOUR LOCATION WITH RESPECT TO THESE SHADOWS WILL DETERMINE THE KIND OF ECLIPSE YOU CAN SEE.

DEAN:  THE GEOMETRY OF THE LUNAR ECLIPSE IS QUITE SIMPLE.  FIRST, THE MOON MUST BE IN THE FULL PHASE, PUTTING THE EARTH BETWEEN THE SUN AND MOON. WHEN THE EARTH, MOON AND SUN ALIGN PERFECTLY, WE GET ECLIPSES.

JAMES:  BECAUSE THE MOON'S ORBIT IS TILTED BY ABOUT 5 DEGREES WITH RESPECT TO THE EARTH'S ORBIT AROUND THE SUN, THE EARTH, MOON AND SUN RARELY ALIGN.  HOWEVER WHEN THEY DO, THE MOON  PASSES THROUGH THE EARTH'S SHADOW.

DEAN:  SINCE EARTH IS SO MUCH LARGER THAN THE MOON, OUR ENTIRE SHADOW CAN COVER THE MOON.  HOW HIGH ABOVE OR BELOW THE EARTH'S SHADOW THE MOON PASSES, DETERMINES THE TYPE OF LUNAR ECLIPSE WE CAN SEE.

JAMES:  IF THE MOON ONLY PASSES THROUGH THE EARTH'S PENUMBRA, WE HAVE WHAT'S CALLED A PENUMBRAL LUNAR ECLIPSE.  THIS CAUSES ONLY A SLIGHT DIMMING OF THE MOON AND IS ALMOST UNNOTICEABLE TO THE AVERAGE MOON WATCHER.

DEAN:  IF ONLY PART OF THE MOON PASSES THROUGH THE EARTH'S UMBRA (THE DARKER INNER SHADOW), WE HAVE WHAT IS CALLED A PARTIAL LUNAR ECLIPSE.  THIS CAUSES A NOTICEABLE DARKENING OF A PORTION OF THE MOON'S SURFACE.

JAMES:  HOWEVER, IF THE MOON PASSES COMPLETELY  INTO THE EARTHS UMBRA, WE HAVE A TOTAL LUNAR ECLIPSE.

DEAN:  NOW IF YOU REMEMBER, 6 MONTHS AGO, WE HAD A TOTAL LUNAR ECLIPSE ON INCOME TAX DAY, APRIL 15TH.  WELL, IT MAY SURPRISE YOU TO KNOW THAT THERE IS AN ALMOST 6 MONTH PATTERN FOR ECLIPSES.  WE CALL THESE ECLIPSE SEASONS.

 DEAN:   THE MOON'S ORBIT AROUND THE EARTH IS TILTED , APPEARING ALMOST LIKE A DINNER PLATE THAT IS TILTED WITH RESPECT TO A DINNER TABLE.  THE POINTS OF INTERSECTION BETWEEN THE MOON'S ORBIT  AND THE PLANE OF THE EARTH'S ORBIT  ARE CALLED NODES.  IF THE NEW MOON AND FULL MOON OCCUR WHEN THE MOON IS AT ONE OF THESE NODES, WE GET AN ECLIPSE.

JAMES:  AS THE EARTH ORBITS THE SUN, IT CARRIES THE MOON WITH IT.  THESE POINTS OF INTERSECTION ALLOW THE SUN, MOON AND EARTH TO ALIGN AT ALMOST 6 MONTH INTERVALS.  SO FOR EXAMPLE, IN APRIL 2014, THE NEW MOON AND FULL MOON WERE ALIGNED WITH THE SUN AND EARTH AND WE EXPERIENCED A TOTAL LUNAR ECLIPSE, AND TWO WEEKS LATER THERE WAS A SOLAR ECLIPSE.

DEAN: IF WE ADVANCE TIME 6 MONTHS TO OCTOBER, THE NEW MOON AND FULL MOON AGAIN ALIGN WITH THE SUN AND EARTH, AND ON OCTOBER 8TH WE WILL SEE ANOTHER TOTAL LUNAR ECLIPSE, AND TWO WEEKS AFTER THAT ON OCTOBER 23RD, THERE WILL BE A PARTIAL SOLAR ECLIPSE.

JAMES:  ALTHOUGH THE 6 MONTH PATTERN OF ECLIPSES HAPPENS RATHER FREQUENTLY, IT'S RARE THAT YOU GET 4 TOTAL LUNAR ECLIPSES IN A ROW.  WE CALL THIS A TETRAD. A TETRAD IS AN EFFECT CAUSED BY THE SHAPE OF EARTH'S ORBIT AROUND THE SUN COMBINED WITH THE TIMING OF ECLIPSE SEASONS, AND THE SEQUENCE OF TETRADS VARIES OVER TIME.

DEAN:  FOR EXAMPLE, BETWEEN 1582 TO 1908 THERE WERE NO TETRADS, BUT THERE ARE 17 TETRADS BETWEEN 1909 AND 2156.  THE PREVIOUS TETRAD OCCURRED IN 2003-2004, AND THE NEXT TETRAD WON'T OCCUR UNTIL 2032.

JAMES:  OKAY, WE'VE GOT OUR SKIES SET UP FOR WEDNESDAY MORNING, OCTOBER 8TH, 2014.  THE MOON WILL ENTER THE PENUMBRA AT 4:15 AM EDT, BUT YOU WON'T NOTICE ANYTHING EXCITING HAPPEN UNTIL ALMOST 5:15 AM WHEN THE MOON BEGINS TO ENTER THE UMBRA.

DEAN:  TOTALITY BEGINS AT 6:25 AM EDT, SO IF YOU HAPPEN TO LIVE ON THE EAST COAST OF THE UNITED STATES, THE MOON WILL BE SETTING JUST AS TOTALITY BEGINS, SO YOU'LL ONLY GET TO SEE THE BEGINNING OF THIS ECLIPSE.  HOWEVER, IF YOU LIVE NEAR THE WEST COAST, YOU'LL GET TO SEE THE WHOLE THING. 

JAMES:  BUT DON'T WORRY, STAR GAZERS.  SINCE THIS IS A TETRAD, YOU GET TWO MORE OPPORTUNITIES TO SEE A TOTAL LUNAR ECLIPSE.  WE'LL HAVE ANOTHER ON APRIL 4TH, 2015 AND THE LAST ONE WILL HAPPEN ON SEPTEMBER 28TH, 2015.

DEAN:  ALL THE LUNAR ECLIPSES AFTER THAT WILL BE EITHER PARTIAL OR PENUMBRAL.  YOU'LL HAVE TO WAIT UNTIL 2018 FOR THE NEXT TOTAL LUNAR ECLIPSE.

JAMES:  SO, MAKE SURE YOU SET YOUR ALARM CLOCKS…

DEAN:  AND REMEMBER TO…

BOTH: KEEP LOOKING UP!

 

Episode #14-39 "I See a Pattern Here"
Air Dates September 29, 2014 - October 5, 2014


ONE MINUTE EPISODE SCRIPT
JAMES: NEXT WEEK WE GET TO EXPERIENCE THE 2ND TOTAL LUNAR ECLIPSE OF THE 2014-2015 TETRAD, WHICH IS A SERIES OF FOUR CONSECUTIVE TOTAL LUNAR ECLIPSES.

DEAN:  SO, IN THIS EPISODE, WE'LL GIVE YOU THE LOW DOWN ON THE OCTOBER 8TH, TOTAL LUNAR ECLIPSE.  LET'S SHOW YOU!

JAMES:  OKAY, WE'VE GOT OUR SKIES SET UP FOR WEDNESDAY MORNING, OCTOBER 8TH.  THE MOON WILL ENTER THE EARTH'S OUTER SHADOW, THE PENUMBRA AT 4:15 AM EDT, BUT YOU WON'T NOTICE ANYTHING  UNTIL ALMOST 5:15 AM WHEN THE MOON  ENTERS THE EARTH'S DARKER SHADOW, THE UMBRA.

DEAN:  TOTALITY BEGINS AT 6:25 AM EDT, SO IF YOU  LIVE ON THE EAST COAST OF THE UNITED STATES, THE MOON WILL BE SETTING JUST AS TOTALITY BEGINS.  HOWEVER, IF YOU LIVE ON THE WEST COAST, YOU'LL GET TO SEE THE WHOLE THING. 

JAMES:  BUT DON'T WORRY, STAR GAZERS.  YOU GET TWO MORE OPPORTUNITIES TO SEE A TOTAL LUNAR ECLIPSE.  WE'LL HAVE ANOTHER ON APRIL 4TH, 2015 AND THE LAST ONE ON SEPTEMBER 28TH, 2015.

BOTH: KEEP LOOKING UP!

 

Star Gazers Home Page Back to WPBT2.org Miami Science Museum Kika Silva Pla Planetarium | Santa Fe College The Cincinnati Observatory Support Star Gazes with your donation