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alright hi everybody I'm Giada from the

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University of Washington I want to say

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thank you to the organizers for putting

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together this whole conference okay so I

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feel like I need to justify talking

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about Venus at an astrobiology

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conference because Venus is extremely

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inhospitable has a surface temperature

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that's high enough to melt lead so

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there's two questions that come to my

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mind when I think about why Venus is

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relevant to astrobiologists one is what

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can Venus tell us about earth some

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people think that measuring the ratio of

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deuterium to hydrogen and menaces

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atmosphere that Venus oops the Venus

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once was more earth-like and maybe have

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had a lot of water on its surface but

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over time and underwent this ronery

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greenhouse process and lost its water

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people think that in the future earth

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will undergo a similar process an earth

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will become Venus like so Venus's

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present state may be Earth's future

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state and then the second question is

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how can Venus import exoplanet studies

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esso planets are something near and dear

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to my heart i love exoplanets so i'm

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always thinking about that in the back

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of my mind when I study these planets I

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think the Venus like planets are

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probably common in the exoplanet

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population because I imagine it sort of

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like Venus's are the end state of

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earth-like planets so they would

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presumably collect and exoplanet

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populations as their stars evolve

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secondly I think that planets with thick

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photochemical Hayes's may also be common

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in the exoplanet population in our own

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solar system of the four terrestrial

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worlds that have substantial atmospheres

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so Earth Mars Venus and Titan two of

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those worlds Venus and Titan have thick

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photochemical Hayes's and earth itself

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some authors think may have had a

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photochemical haze in its past so it's

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interesting to me to try to understand

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what we can learn about the surface

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environments of photochemical chemically

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hazy enshrouded worlds I think that has

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significant implications to future

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remote sensing and planetary

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characterization of extrasolar planets

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oh there's a movie but it's not playing

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oh well pretend the little volcano is

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going off an i oh they're so this is the

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innermost moon of Jupiter IO IO is the

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most volcanically active body in the

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solar system because it's on a slightly

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eccentric or

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a bit near Jupiter and Jupiter is

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putting tidal energy into IO and melting

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its interior and so I Oh has these

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incredibly huge volcanoes like that one

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spewing off the limb of the planet a

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class of world's proposed by one of my

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collaborators at the University of

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Washington Rory Barnes has proposed that

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he thinks that you can get tidal Venus's

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which are worlds that have a high enough

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heat flux driven by tidal heating close

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to their star so these are worlds on

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slightly eccentric orbits or worlds that

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are in the process of Title II circular

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izing their orbits and if they have a

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high in a fleet heat flux about 300

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watts per square meter you can actually

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drive those planets into a runaway

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greenhouse and get what's called a tidal

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Venus Rory believes that the danger zone

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for getting tidal Venus's exists for

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star is less than about point one solar

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masses and that doesn't mean all of

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those stars necessarily have tidal

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Venus's it just means they could have

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tidal Venus's depending on the various

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properties the planets orbits and their

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masses and the really really important

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thing about tidal Venus's is that four

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stars less than point three solar masses

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tidal Venus's can exist within the

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habitable zones of stars so they may

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potentially confuse future

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characterization missions if we find

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these planets and don't understand what

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we're looking at what this is showing is

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um I don't want to spend too much time

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talking about this but this is showing

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the planet star separation angle for

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various earth-like hypothetical

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earth-like planets around the nearest

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stars in the nearest 20 or so parsecs in

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the higher part goes catalog so for the

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non astronomers just to remind you a

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dwarf so the hottest most massive type

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of stars that I've plotted here and then

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endures that I've plotted are the

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coolest least massive type of star so

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the planet star separation for endures

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in the Hannibal zone is going to be less

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than the planet star separation for a

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Dwarfs so these are the stars that are

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below the match / hold which could host

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a title Venus and again this doesn't

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mean these stars do have title Venus's

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even if they do have a planet in the

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habitable zone it just means that they

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possibly could the title Venus's could

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not be detected by the first generation

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of terrestrial planet finder 'he's

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that's what's these two lines are so

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those are the inner working angles of

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the terrestrial planet finder zaz they

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were proposed initially and so all of

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them are below that

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threshold but these planets could be

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detected if they exist through transit

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transmission spectroscopy about thirty

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percent of the nearby and dwarfs could

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host tidal Venus's okay so now my work

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is seeing through the pale yellow cloud

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so how do we actually characterize these

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worlds the way you do is you have to use

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what's called these nights I'd spectral

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windows they were discovered by Allen

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and Crawford in 1984 these special

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windows are you don't want to think of

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them as literal places on the planet

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where the clouds are thin and you're

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actually you know peering through holes

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in the clouds these are special windows

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so you want to think of it in wavelength

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space so they exist from about one to

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2.5 microns at least the ones that I'm

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interested in and their places in the

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spectrum of the planet where gases are

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not significantly absorbing the spectrum

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is relatively transparent so you can

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look in these wavelength regions and you

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can probe deep down into the atmosphere

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and in some cases for example the one

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micron window you can probe all the way

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down to the surface of the planet so

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that's great because this gives us

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information about the surface conditions

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of this completely photochemically

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enshrouded planet so what we did is we

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observe them in November and December of

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2010 using the APO 3.5 meter telescope

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the triple speck instrument which is a

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spectrometer with a range from 1 to 2.5

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microns and a resolution of about 3,500

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these are night side windows because you

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can't observe them on the dayside of the

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planet unfortunately at least in the

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case of Venus because in this case what

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you're sampling through the windows is

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thermal emission which gets completely

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dwarfed and swamped by reflected

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sunlight if you try to observe them on

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the day side ok so just prove to you

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that you can see the surface of Venus

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from Earth what you do is you measure

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the one micron brightness in each pixel

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then you can build up a map of

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brightness variations and this little

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guy here that's Aphrodite Terra it's

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kind of hard to see but it's darker than

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the surrounding Plains and the reason

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why it's darker is because it's higher

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in elevation Aphrodite tara is a

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Highland Plateau about the size of South

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America and it's about four kilometers

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above the plains so the adiabatic lapse

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rate on Venus is about seven Kelvin per

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kilometer so this thing

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about 30 calvin cooler than the planes

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that's why it's darker if you were to

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sort of naively try to measure the

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brightness temperature of Venus by

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measuring the effective temperature of

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the cloud deck you would get a very cold

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temperature it's like 218 degrees Kelvin

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which is grossly mischaracterizing the

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surface environment of the planet so if

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you were to naively believe that you

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would completely misunderstand what's

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going on here the actual surface

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temperature of Venus is about seven

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hundred and thirty degrees Kelvin and

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using in particular the one micron

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window again which is about ninety six

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percent surface thermal emission you can

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measure the surface temperature through

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the through the thick atmosphere you

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don't need to descend a probe into the

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atmosphere you can actually do it

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remotely so again yeah that measures the

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surface and this entire wavelength range

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from 12 to 1 point 3 microns you can

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measure the lowest scale height okay so

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the next thing I did is I used the

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spectra that we collected from Apache

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point observatory and combine those with

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radiative transfer models to try to get

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a handle on the cloud opacity over the

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planet and also to measure the abundance

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of minor atmospheric species so

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obviously the major atmospheric species

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for Venus is carbon dioxide but it has a

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lot of other gases that are present much

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less abundant levels so one thing I did

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was I measure the cloud opacity so these

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are a radiative transfer models where

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I'm changing the opacity of the lower

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cloud deck the relative heights of the

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spectral windows are very very sensitive

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to the opacity of the lower cloud deck

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you can see that as you go from let's

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see lower opacity clouds to hire opacity

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clouds the windows change heights

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absolutely but they also chain sites

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relative to each other so you can use

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that relative effect to quantify the

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cloud opacity which is what I did here

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so what you're looking at is this is

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just orient you we're looking at the

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night side of the planet each of these

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columns is a different nights that I

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observe the planet it looks like it got

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little cut off on here this one at the

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very end let's see so this is the first

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night this is actually the last night

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and the very last one is all the nights

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co added on top of each other just to

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look for long-term persisting patterns

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so the cloud

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measures the brightness of the clouds in

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the places where it's very bright or red

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is places where the clouds are thin and

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your sampling lower into the hotter

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atmosphere and then vice versa where

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it's dark or blue or you're sampling

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higher in the atmosphere where it's

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cooler I measured the cloud opacity

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using my radiative transfer models here

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and you can see that there is a

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correlation between places where the

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clouds are thinner and places where you

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again would expect from the cloud maps

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that it would be thinner so these this

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row here is built up from the models and

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this one is from the data and there's a

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good correspondence between what I would

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expect it's really important to remove

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cloud opacity features that are

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wavelength dependent because those can

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contaminate your measurements of minor

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atmospheric species which was the next

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thing that I wanted to do so first I had

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to use these wavelength dependent cloud

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opacity maps to remove these features

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another really nice thing about the

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Venus spectral windows is that they're

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sensitive to different altitudes so when

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you're measuring the abundances of

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various species you can actually build

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up vertically resolve profiles depending

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on the window that you measure them in

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so in the 1.18 Mike on window your

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sensitive lowest in the atmosphere when

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you get up to the 2.5 microns window

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you're probing just below the lower

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cloud deck okay so I know there's a lot

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of green on this slide but these are my

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water maps so this is just measuring the

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water in each pixel across the surface

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of the planet Venus's atmosphere is

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extremely dry the water vapor abundance

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is about 30 parts per million that's a

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lot less than the earth has by a lot and

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you can see that you get these

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vertically so this is 40 to 16

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kilometers 16 to 30 30 to 45 kilometers

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you can build up what it looks like at

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different heights in the atmosphere and

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then drawing your attention to the sorry

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this should not have been there he's got

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all screwed up but um drawing your

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attention to the lower cloud opacity and

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the 2.3 micron water maps I did notice

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that there's some correlations this

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one's probably hard to see but there are

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some correlations where sometimes

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thicker cloud regions have less water

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and thinner cloud regions have more

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water this was an effect that has

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previously been reported by some of the

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this Express team members and what may

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be causing this is cloud subsidence

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where you have a cloud parcel in the

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atmosphere that some atmospheric

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downdraft pulls it lower into the

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atmosphere then the h2so4 droplets that

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make up the cloud disassociate into

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water vapor and so2 so in some places

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where you have thinner clouds that may

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be places where the cloud subsidence is

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occurring and you may be getting thicker

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water from that because it's producing

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water vapor I also measured HCl hydrogen

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chloride which is abundant at about

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point five parts per million and co

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which has a really interesting spatial

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distribution that's previously been

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reported in the literature by cotton at

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all and what's probably going on here is

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co is being produced photochemically

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from co2 higher in the atmosphere and

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then it down wells at the poles so you

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get this abundant more higher abundance

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at the poles and then by the time it

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gets to the equatorial region in these

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kind of circulating cells it's a lot

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more depleted because it um reacts with

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other species and becomes other species

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like OCS okay so take away points is the

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main point is that completely crap cloud

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enshrouded worlds and completely haze

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and shrouded world even if they're 100%

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enshrouded it's not the end of the day

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for trying to sense their surface

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environments and characterize what's

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going on in their surfaces so I think

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atmospheric windows are very important

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because I think hazy planets are

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probably important in the exoplanet

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so for your cloud opacity you you've

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been using water clouds there so the

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cloud of past me i have it i was gonna

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cuz there was a modern data as well

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right yeah let me where was my club

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sorry so the clouds are h2so4 droplets

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sulfuric acid droplets and i'm basing

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them off of this crisp 1986 model and I

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should have mentioned that these units

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are in units of the sort of default

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opacity in the Christmas 1986 model

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they're not sort of absolute units so

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this is 3 times a crisp cloud opacity

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and this is 0 point 05 so is the h2o

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supply opacity data in that paper or

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ready get the opacity the Ambassador

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yeah i got it from Dave Chris he's one

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of my collaborators okay thanks what is

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the specific chemical role of the HCL

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that you measured the specific what

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00:13:51,310 --> 00:13:48,590
chemical role of the HCL that you were

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00:13:53,950 --> 00:13:51,320
looking at yeah so agency hell I'm

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trying to remember now et al has not

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changed in abundance over the last 40 or

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however many years that we've measured

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it so it's thought to be an equilibrium

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with the surface and I cannot remember

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how they think it's produced I don't

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think they think it's volcanic Lee

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produced like some of the species in the

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atmosphere yeah I know there is some

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cloud chemistry between chlorine that

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00:14:22,460 --> 00:14:16,550
you get in the atmosphere in the HCL but

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I didn't understand this title Venus

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00:14:36,350 --> 00:14:33,870
stuff I think so at i/o you have this

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00:14:39,320 --> 00:14:36,360
Laplace resonance with Ganymede and

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00:14:43,130 --> 00:14:39,330
Europa to not get into this tidal

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00:14:46,070 --> 00:14:43,140
locking but how does it work at a vino

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00:14:49,310 --> 00:14:46,080
surrounding a dumpster right so Rory

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00:14:51,530 --> 00:14:49,320
would be the person to ask that but the

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00:14:53,660 --> 00:14:51,540
way it works is you have to assume that

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00:14:55,490 --> 00:14:53,670
the planets not in a circular orbit and

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00:14:58,280 --> 00:14:55,500
you have to assume that the time that it

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00:14:59,840 --> 00:14:58,290
takes to Title II circularize is shorter

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00:15:01,430 --> 00:14:59,850
than the timescale for it to undergo

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00:15:04,010 --> 00:15:01,440
this desiccating greenhouse and that's

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00:15:05,600 --> 00:15:04,020
how you get a title Venus so somehow you

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00:15:08,240 --> 00:15:05,610
have a planet that's either persisting

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00:15:09,890 --> 00:15:08,250
in a sort of subtly elliptical orbit

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00:15:11,720 --> 00:15:09,900
perhaps there's another planet in there

399
00:15:14,330 --> 00:15:11,730
just like around Jupiter that's keeping

400
00:15:15,740 --> 00:15:14,340
those moons in a elliptical orbit or you

401
00:15:17,030 --> 00:15:15,750
have a planet that's being tidally

402
00:15:18,710 --> 00:15:17,040
circularized so it starts in an

403
00:15:21,080 --> 00:15:18,720
elliptical orbit one it can be tidally

404
00:15:23,240 --> 00:15:21,090
heated and then it circular rises so if

405
00:15:25,430 --> 00:15:23,250
that occurs in the long enough time

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00:15:27,440 --> 00:15:25,440
frame for it to undergo a desiccating

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00:15:29,540 --> 00:15:27,450
greenhouse then you can trigger a title

408
00:15:32,810 --> 00:15:29,550
greenhouse so these are planets that are

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00:15:34,640 --> 00:15:32,820
close in to low mass stars it's directly

410
00:15:36,830 --> 00:15:34,650
analogous to the Jupiter system and

411
00:15:39,770 --> 00:15:36,840
you're producing a lot more heat than

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00:15:41,870 --> 00:15:39,780
you are on io io has like two watts per

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00:15:43,610 --> 00:15:41,880
square meter whereas for tidal Venus's

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00:15:44,900 --> 00:15:43,620
you need 300 watts per square meter so

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00:15:49,460 --> 00:15:44,910
there's there's quite a difference but