WPBT2's Star Gazers

Episode #13-08 "I Eat Green Caterpillars! When Looking at Jupiter"
Air Dates Febtuary 25, 2013 - March 3, 2013

JAMES: Welcome to Star Gazers. I'm James Albury, director of the Kika Silva Pla Planetarium in Gainesville Florida.

MARLENE: And I'm Marlene Hidalgo, science teacher from Miami-Dade County Florida.

DEAN: And I'm Dean Regas, astronomer from the Cincinnati Observatory and we're here to help you be sure you know what you're seeing in the night sky when you…

ALL: Look up!

MARLENE: By the title of this week's episode, you would think we actually eat green caterpillars…

DEAN: We don't?

JAMES: Heh… speak for yourself.

DEAN: But… we always think of green caterpillars whenever we look at Jupiter. Why? Let's show you.


DEAN: Jupiter is the largest of all the planets in our sun's family and is number 5 from the sun, our Earth being number 3. Now our Earth is, on average 93 million miles away from the sun, whereas Jupiter's average distance is 484 million miles. But because Jupiter is a much slower moving planet than our Earth, Jupiter and Earth constantly vary their distance from each other.

JAMES: When Jupiter is at its farthest distance from us and is on the other side of the sun as seen from Earth, it can be as far as 593 million miles away but once every year our Earth and Jupiter line up on the same side of the sun and are many millions of miles closer to each other. Whenever this happens we say Jupiter is at opposition because Jupiter is opposite the sun in the sky as seen from Earth.

MARLENE: …And when Jupiter is at opposition it is always at its closest and brightest and best for viewing. Jupiter was at opposition back on December 1st, 2012, only 4 astronomical units away and although it's 100 million miles farther away this week, at 5 astronomical units, it is still great for viewing in a small telescope. And that's where the" I eat green caterpillars" comes in. Let's explain.


MARLENE: O.K., we've got our skies set up for about an hour after sunset your local time any night the next couple of weeks facing west where one of the brightest objects you'll see will be Jupiter.

JAMES: Jupiter will be right near the horns of Taurus the Bull, and if you're facing southwest, you can find Taurus by drawing a line from Orion's belt down toward the western horizon. And it is by far the easiest planet to see through even the smallest telescope.

DEAN: In fact you can see bands of weather systems completely encircling it and sometimes its famous "great red spot", which is a giant storm system larger than 3 Earths lined up. You'll also notice something that attracted the attention of the first person who ever looked at Jupiter through a telescope and that is 4 tiny pinpoints of light which seem to extend out from Jupiter's equator and which constantly change their position from night to night.


MARLENE: Sometimes you'll see two lined up on one side and two on the other. Sometimes you'll see three and one, sometimes four lined up on one side and so on. In fact these 4 lights are so bright you can even see them with binoculars. These are Jupiter's four largest moons and they're called the Galilean satellites because they were first discovered by Galileo in 1610.

JAMES: Now, although Jupiter (as of today) is known to have over 64 moons, these 4 moons are the biggies! And in fact all but one of these four is larger than our moon. Their names in their order out from Jupiter are Io, Europa, Ganymede and Callisto. And when I was younger, I had a difficult time remembering their correct order until one day Jack Horkheimer shared how he remembered them.

DEAN: Jack decided to take the first letter of each moon's name and think of a catchy phrase that he would never forget. Heaven only knows why he came up with "I" for Io, "eat" for Europa, "green" for Ganymede and "caterpillars" for Callisto. But he did and we've never forgotten their correct order since.

MARLENE: So just remember "I eat green caterpillars" and impress your friends with the fact that you know the correct order of Jupiter's four largest moons!

JAMES: And speaking of the color green, we have another holiday moon-Jupiter pairing for you. Remember the moon-Jupiter conjunction on Christmas night 2012? Well, the moon and Jupiter are going to be super close in the sky again on St. Patrick’s day! On March 17th, just after sunset, look toward the west and you'll see a waxing crescent moon less than a degree away from Jupiter.

DEAN: So, happy green caterpillar eating, and as always…

ALL: Keep looking up!


Episode #13-08 "I Eat Green Caterpillars! When Looking at Jupiter"
Air Dates Febtuary 25, 2013 - March 3, 2013

DEAN: Welcome to Star Gazers. Now, we don't actually eat green caterpillars…

JAMES: We don't?

DEAN: No. But… we always think of green caterpillars when we look at Jupiter. Why is that? Let's show you!


DEAN: Jupiter is going to be visible in the western sky just after sunset over the next few weeks and it will have a really close visit by the moon on the evening of St. Patrick's Day, March 17th.

JAMES: The color green is important because you can remember the order of Jupiter's four largest moons by using the catchy phrase, "I eat green caterpillars". You simply take the first letter of each of the moon's names.

DEAN: "I" for Io, "eat" for Europa, "green" for Ganymede and "caterpillars" for Callisto. Once you do that, you'll never forget their correct order.

JAMES: So just remember "I eat green caterpillars" and impress your friends!

BOTH: Keep looking up!


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