Deeper Into Jeopardy! XIX: To the Exoplanets! – $800

Jeopardy! category: TO THE EXOPLANETS! (21-05-2014)

$800 clue: In 2013 Caltech scientists announced there are more than 100 billion planets in this alone–about one per star

Correct response

The gist: As Dr. David Bowman says in Arthur C. Clarke’s novel 2001: A Space Odyssey (but not in Kubrick’s movie): “Oh my god – it’s full of stars!” 

Of course, Dr. Bowman was talking about the mysterious monolith that he had unwittingly been sent to explore, and we’re talking about something much more mundane, if not much less fascinating – our home galaxy, the Milky Way. Our galaxy gets its handle from the Latin via lactea, milky way or road, in turn from the Greek galaxias kuklos or milky circle, because it appears to the naked eye as a liquidy white mass without distinct stars.* Of course, we now know that all of the visible stars in the sky are part of the Milky Way galaxy, but the ancients didn’t know that – they assumed, understandably enough, that the individually-resolvable stars were a different sort of animal than the bright white band they saw “behind” them. The first observation that the Milky Way consists of a large number of stars was made by Galileo and his telescope in 1610. William Herschel tried to draw a map of the Milky Way in 1785, but was quite unsuccessful – he put our star near the centre, when in fact we’re quite near the edge. Of course, while we know where we’re located within the galaxy we can’t actually take a picture to make sure, because we’ve never sent a camera far enough away to take a picture of the whole thing – in fact, the furthest human-made object, Voyager I, is just barely outside our solar system.

But anyway, we do know that the Milky Way is a spiral galaxy a bit over 100 000 light years in diameter, with a lot of stars – estimates vary from about 100 billion to 400 billion. The clue’s Caltech researchers arrived at their estimate of planets by taking a close look at just one star, Kepler-32, which they take to be similar enough to about 3/4 of the galaxy’s stars to be a representative sample. By crunching a lot of numbers that have been gathered over the years, they’ve come to their guess of 100 billion planets – that’s one per every star on the low end of estimate, but still, as one of the researchers said, “a staggering number.”

A mosaic panorama of the whole Milky Way as seen around planet Earth

The clue: This one was a triple stumper, which is surprising since the subject matter doesn’t seem too hard. It is, however, very awkwardly written, which I suspect is what tripped the players up. It’s sort of strange to refer to the Milky Way as “this alone” – and following it up with a couple more words after a hyphen just makes it sound weirder. I don’t think a player as good as Julia Collins would miss this one if it was written a little better.

In Jeopardy!: “Milky Way” appears in 49 clues (if you count the chocolate bar) and one FJ! clue in the J!Archive, plus one category called “Milky Way” that was about dairy, not astronomy. The galaxy’s spiral shape comes up in seven clues, but beyond that, it’s mostly just used as a set-up for general astronomy clues. But if a clue is asking you to name a galaxy, it’s usually this one – if the clue indicates that it’s a different one from ours, it’s probably Andromeda.

* The sugar galactose has a closer relationship to actual milk than do galaxies.

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