WPBT2's Star Gazers

Episode #12-14 "Going Retrograde With Venus And Mars"
Air Dates April 2 - April 8, 2012



FIVE MINUTE EPISODE SCRIPT
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. 

DEAN: The ancients called the planets, "wandering" stars because they moved across the static background stars.

JAMES: And you can find four planets at night: Venus, Mars, Jupiter, and Saturn.  And two of them are wandering like crazy right now.

DEAN: let's show you Venus and Mars!

(STOP DROP)

DEAN: Okay, we have our sky set to Friday April 6th at 9 pm facing west.  There you'll find two really bright star-like objects.  The one lower in the sky and slightly dimmer is the giant planet Jupiter. 

JAMES: Make sure to catch Jupiter just as darkness falls because it'll be setting fast.  Now, let's move the sky forward to 10 pm.  Notice how the stars all shifted down to the west.  Jupiter is now just barely above the horizon.     

DEAN: About 20 degrees above Jupiter you’ll find the brightest planet visible from earth: dazzling Venus.  This is prime Venus-viewing season because Venus just passed its greatest elongation from the sun.

JAMES: This means that the sun and Venus seem farthest apart - separated by 46 degrees in the night sky.  So long after the sun sets, we can still see Venus blazing away in the west. 

DEAN: As Venus orbits the sun it will appear to move across the much farther background stars.  When it passes the earth and crosses in front of the sun, Venus will pop out in the morning sky.  That's when we call it the morning star.  Then, as Venus swings behind the sun it will shift from being visible in the morning to sparkling in the evening sky - like it is now.  That's when we call it the "evening star".

JAMES: Venus shifts a little bit each day.  The stars keep flying in formation but Venus goes it alone.  Over the course of a season if we trace Venus place in the sky at the same time every day it makes this big loop.  Then if we chart the motion over the course of eight years, we get some interesting patterns.  Venus’ retrograde motion comes in 5 forms.  A squiggle down… a loop down… a zig-zag… a loop up and a squiggle up.  That’s five patterns in eight years.  Then the pattern repeats itself almost exactly.   

DEAN: The ancient Mayans were crazy about Venus.  After observing the planet for centuries, the Mayans developed an incredibly accurate set of Venus tables that could predict where Venus would be in the sky for years.  After 500 years the tables would only be off by one day!  The Mayans noticed this retrograde motion and the five different patterns that it formed.  They gave each manifestation of Venus a personality represented by the 5 different creatures on the Venus tables. 

JAMES: Let's leave Venus in the west and turn to the eastern sky.  There we'll find the moon next to two star-like objects.  The one closest to the moon (just to the left of it) is the blue star Spica in the constellation Virgo the maiden.  The other object is the ringed planet, Saturn.  This inconspicuous planet is amazing to see in a telescope.  And you'll be seeing a lot of it since it's now closest to the earth for the year.

DEAN: Up a lot higher in the southeastern sky you'll discover another pair of stars.  But look closely because one is decidedly redder than the other.  The one on the right is the star Regulus in the constellation Leo the lion.  The redder one on the left is the planet Mars.  Mars has an interesting retrograde motion too.  Let’s check it out up close. 

JAMES: Mars generally moves east across the background stars - day by day by day.  But for a while it will stop, turn around, and head west.  But just for a little while.  Then it'll stop and head back east again. 

DEAN: What a crazy motion.  Imagine the headaches these Martian loop-di-loops caused the ancient astronomers! 

JAMES: What's happening is when the earth catches up to slower Mars, it changes our perspective.  Mars will appear to reverse course and go backwards across the stars.  When the earth passes Mars enough, it appears to stop and head forward again.

DEAN: So find four planets in the evening skies this week: Jupiter, Venus, Mars, and Saturn.

JAMES: And watch Venus and Mars moving in retrograde

BOTH: Keep looking up!

 

Episode #12-14 "Going Retrograde With Venus And Mars"
Air Dates April 2 - April 8, 2012



ONE MINUTE EPISODE SCRIPT
JAMES: The ancients called the planets, wandering stars because they moved across the background stars.

DEAN: And Venus and Mars are wandering like crazy right now.

(STOP DROP)

DEAN: Any night this week you'll find Jupiter low in the west and Venus, higher and brighter in the west.

JAMES: But keep watching because they'll move from night to night. Venus shifts a little bit each day as the stars keep flying in formation. Over the course of a season, if we trace Venus’ place in the sky at the same time every day, it makes this big loop. That's its retrograde motion.

DEAN: High in the southeastern sky you'll find red Mars next to a blue star called Regulus. Mars generally moves east across the background stars - day by day by day. But for a while it will stop, turn around, and head west in retrograde. But just for a little while. Then it'll stop and head back east again.

JAMES: That's how the planets seem to appear from an ever-moving earth.

BOTH: Keep looking up!

 

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