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From The Desk of...The Chief Scientist

"Pluto is (not) a Planet"

Written by Paul Sutter on Monday, 10 April 2017. Posted in From The Desk of...The Chief Scientist

Recently Joe Heimlich, co-director of COSI's Center for Research and Evaluation, fired off a quick question for me: rumors abound that Pluto may be reinstated as a planet. Is it true? What gives? (I'm paraphrasing).

In 2006 the International Astronomical Union adopted the following requirements for planethood: An object must 1) orbit the sun, 2) be large enough that its own self-gravity pulls it into a spherical shape, and 3) clear the neighborhood of its orbit of any debris.

With its large moon Charon, and all the other junk in the outer solar system, Pluto failed requirement 3 and was demoted to "dwarf planet" status.

The decision was met with heavy criticisms within the astronomical community. Why should a definition of an object rely on its environment and not just on properties of the object itself? If the Earth were moved to the orbit of Pluto, we would lose our planet status - how does that make sense? Why weren't all interested parties involved in the vote back in 2006? And so on.

Recently a group of astronomers proposed a new definition of planet: it must be large enough to make it round, and that's it. The new definition covers Pluto and friends, "rogue" planets that aren't bound to any star, and also upgrades some large moons to planetary status.

The debate continues, but one thing is clear: we will never return to a state with exactly 9 planets in the solar system. Either it will continue to be 8 or be around...10,000. We'll see.

"But Can We Eat It?"

Written by Paul Sutter on Tuesday, 04 April 2017. Posted in From The Desk of...The Chief Scientist

Tyler Fox, one of COSI's Floor Faculty Managers, was working in the Planetarium the other day and encountered a difficult question. What if someday we discover alien life - say, in the subsurface oceans of Europa or living on a distant exoplanet around another star - and it's as complex as life here on Earth. Not just single-celled critters that we only get to gawk at through a microscope, but large organisms with thriving ecosystems.

Of course we would first celebrate a major triumph of scientific inquiry and human philosophy, answering one of the most important questions of our species: "Are we alone?"

But Tyler's gang didn't care about that question. They cared about the second most important question of our species: "Could we eat it?"

That's actually a pretty challenging question. On one hand, complex molecules like sugars and amino acids are built from (literally) universal ingredients. We've even detected glycine, the simplest amino acid, on comets and identified glycolaldehyde, a simple sugar, in interstellar nebulae. So presumably alien life would be built from the same basic blocks as their Earth-born cousins, rendering them eatable.

But digestible is another matter. There are many, many things just on the Earth that are either too tough, too poisonous, or too poor in nutrients to eat. Humans are omnivorous, but not that omnivorous. There are many steps to go from "contains nutrients" to "we can acquire those nutrients" to "we can enjoy doing so."

Could we eat alien life? I guess there's only one way to find out.

"The Constant Eclipse"

Written by Paul Sutter on Monday, 20 March 2017. Posted in From The Desk of...The Chief Scientist

When the total solar eclipse visits the US this August 21st, the whole experience will last about three hours. Here in Columbus the party starts around 1pm, when the disk of the moon begins to cover up the face of the sun. An hour and a half later, at 2:30pm, we will reach maximum coverage. That maximum ends at...2:32pm. It will be another hour and a half until the moon fully exits the sun, but for some that maximum simply isn't enough.

Hence the anonymous question posted on my COSI whiteboard recently. The eclipse is covering the whole country, entering the US on the Oregon coast near the town of Newport and exiting the Atlantic side via Charleston, South Carolina. Any one spot along the path connecting those two cities will experience totality for around two minutes tops.

But what if we could drive - or better yet, fly - along that path, "catching" the totality in Oregon and riding it all the way to South Carolina? How fast would we have to go to really get the greatness of the Great American Eclipse?

Newport goes dark around 10:20am PDT, and Charleston doesn't follow suit until around 2:50pm EDT, so the most you're going to get for this eclipse is an hour and a half. Due to the moon's orbit the eclipse path doesn't take a direct line between the two cities, but we can take the great circle distance of 2,500 miles as good enough approximation, leading to a speed of 1,600 mph.

That's twice the speed of sound.

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