P: So, we now know Jupiter has lots of moons, over 60 of them, but it's one of Jupiter's four Galilean moons, the moons first seen in 1610 by the astronomer Galileo, its the innermost of these, the one called Io that I'd like to focus on today. lo's fairly small like Earth's moon, but farther from the sun, so you might picture it as a boring, rocky place with nothing much going on, kind of like our own moon, only colder, but when the Voyager spacecraft took the first close-up pictures of the surface of Io in 1979, we learned how mistaken that assumption would be.Voyager's cameras recorded hundreds of volcanoes there; some erupting violently even as the spacecraft was passing by.
S1: Do the pictures show impact craters on Io, like our moon has?
P: No. lo's so volcanically active that any meteor impact craters would quickly be covered over by volcanic debris and this indicates something really surprising about lo's interior.
S1: That it must be very hot.
P: Very. You took the words right out of my mouth, but all that heat is puzzling. You see, our own moon is pretty cold inside and since lo's not much bigger than Earth's moon is and a lot farther fromthe sun, it ought to be at least as cold. I mean, neither have much heat to begin with and just about all of that original heat would have been lost by now.
Question 1 of 6
What is the main purpose of the lecture?
O A. To discuss similarities in howEarth's Moon and Io originally formed
O B. To compare and contrast Jupiter's four Galilean moons
O C. To explain why Io differs so greatly from Earth's Moon
O D. To demonstrate howtidal forces affect Jupiter
Question 2 of 6
What discovery by the Voyager spacecraft does the professor mention?
O A. Io is volcanically active
O B. Io has several large impact craters
O C. lo's orbit is highly irregular
O D. Io is closer to Jupiter than previously thought