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  • I am in search of another planet in the universe where life exists.

  • I can't see this planet with my naked eyes

  • or even with the most powerful telescopes

  • we currently possess.

  • But I know that it's there.

  • And understanding contradictions that occur in nature

  • will help us find it.

  • On our planet,

  • where there's water, there's life.

  • So we look for planets that orbit at just the right distance

  • from their stars.

  • At this distance,

  • shown in blue on this diagram for stars of different temperatures,

  • planets could be warm enough for water to flow on their surfaces

  • as lakes and oceans

  • where life might reside.

  • Some astronomers focus their time and energy on finding planets

  • at these distances from their stars.

  • What I do picks up where their job ends.

  • I model the possible climates of exoplanets.

  • And here's why that's important:

  • there are many factors besides distance from its star

  • that control whether a planet can support life.

  • Take the planet Venus.

  • It's named after the Roman goddess of love and beauty,

  • because of its benign, ethereal appearance in the sky.

  • But spacecraft measurements revealed a different story.

  • The surface temperature is close to 900 degrees Fahrenheit,

  • 500 Celsius.

  • That's hot enough to melt lead.

  • Its thick atmosphere, not its distance from the sun, is the reason.

  • It causes a greenhouse effect on steroids,

  • trapping heat from the sun and scorching the planet's surface.

  • The reality totally contradicted initial perceptions of this planet.

  • From these lessons from our own solar system,

  • we've learned that a planet's atmosphere

  • is crucial to its climate and potential to host life.

  • We don't know what the atmospheres of these planets are like

  • because the planets are so small and dim compared to their stars

  • and so far away from us.

  • For example, one of the closest planets that could support surface water --

  • it's called Gliese 667 Cc --

  • such a glamorous name, right, nice phone number for a name --

  • it's 23 light years away.

  • So that's more than 100 trillion miles.

  • Trying to measure the atmospheric composition

  • of an exoplanet passing in front of its host star is hard.

  • It's like trying to see a fruit fly

  • passing in front of a car's headlight.

  • OK, now imagine that car is 100 trillion miles away,

  • and you want to know the precise color of that fly.

  • So I use computer models

  • to calculate the kind of atmosphere a planet would need

  • to have a suitable climate for water and life.

  • Here's an artist's concept of the planet Kepler-62f,

  • with the Earth for reference.

  • It's 1,200 light years away,

  • and just 40 percent larger than Earth.

  • Our NSF-funded work found that it could be warm enough for open water

  • from many types of atmospheres and orientations of its orbit.

  • So I'd like future telescopes to follow up on this planet

  • to look for signs of life.

  • Ice on a planet's surface is also important for climate.

  • Ice absorbs longer, redder wavelengths of light,

  • and reflects shorter, bluer light.

  • That's why the iceberg in this photo looks so blue.

  • The redder light from the sun is absorbed on its way through the ice.

  • Only the blue light makes it all the way to the bottom.

  • Then it gets reflected back to up to our eyes

  • and we see blue ice.

  • My models show that planets orbiting cooler stars

  • could actually be warmer than planets orbiting hotter stars.

  • There's another contradiction --

  • that ice absorbs the longer wavelength light from cooler stars,

  • and that light, that energy, heats the ice.

  • Using climate models to explore

  • how these contradictions can affect planetary climate

  • is vital to the search for life elsewhere.

  • And it's no surprise that this is my specialty.

  • I'm an African-American female astronomer

  • and a classically trained actor

  • who loves to wear makeup and read fashion magazines,

  • so I am uniquely positioned to appreciate contradictions in nature --

  • (Laughter)

  • (Applause)

  • ... and how they can inform our search for the next planet where life exists.

  • My organization, Rising Stargirls,

  • teaches astronomy to middle-school girls of color,

  • using theater, writing and visual art.

  • That's another contradiction -- science and art don't often go together,

  • but interweaving them can help these girls bring their whole selves

  • to what they learn,

  • and maybe one day join the ranks of astronomers

  • who are full of contradictions,

  • and use their backgrounds to discover, once and for all,

  • that we are truly not alone in the universe.

  • Thank you.

  • (Applause)

I am in search of another planet in the universe where life exists.

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    Zenn posted on 2017/01/20
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