Jupiter is the largest planet in our solar system, big enough to fit more than 1,300 Earths inside it and weighing in at just under 318 Earth masses. Even though it’s five times further away from the sun than Earth is, it’s so large that at night it is often the brightest object in the sky.
People have observed it with telescopes almost since the invention of the telescope in 1608. In fact, studying Jupiter with his telescope in 1610, Galileo discovered its orbiting moons and concluded that Earth wasn’t the center of the universe. By the 1970s, spacecraft were flying past Jupiter, and in the 1990s an orbiter named after Galileo circled around.
Scientists learned that Jupiter’s rapid rotation (its day is 10 hours long) makes it bulge at the equator and flatten at the poles, and that it has faint rings and dozens of moons. The giant planet is mostly composed of hydrogen and helium and is surrounded by deadly radiation belts, the most intense in the solar system.
However, after studying Jupiter for hundreds of years, astronomers still had some basic questions: Is there a dense core under all that atmosphere? How, when, and where did it form, and what does that tell us about the formation of the rest of the solar system? What do the north and south poles of Jupiter look like?
To answer these and other questions, the Juno spacecraft was launched on a 5-year journey to Jupiter in 2011. From the first images sent back in 2016 to the data continuing to be received today, the result has been a series of surprises and fascinating puzzles. Steve Levin, the project scientist for Mission Juno, talks about what’s been learned so far, what it might mean, and what’s next in the ever-unfolding story of Jupiter.
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The Grand Tour of the Solar System series treks to the Sun and the four inner terrestrial planets before traveling outward to the asteroid belt, four Jovian planets, and beyond. At each session, a professional astronomer explores a solar system body, presenting the latest research.
Following the talk and a question-and-answer period, Peter Plavchan, a professor of physics and astronomy at George Mason University, brings that night’s sky right into participants’ living rooms via remote control of the university observatory, weather permitting.
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