Podcaster: Tony Darnell
Title: Deep Astronomy – The Earth As An Exoplanet
Organization: Deep Astronomy
Link : https://deepastronomy.space
Twitter @DeepAstronomy, https://facebook.com/DeepAstronomy
YouTube: https://www.youtube.com/deepastronomy
Description: From August 22, 2018
Are we alone? How unique is our Earth?
Should the hunt for life beyond Earth uncover a multitude of habitable worlds and few (if any) inhabited ones, humanity would begin to understand just how lonely and fragile our situation is. On the other hand, if our hunt yields a true diversity of inhabited worlds, then we would learn something fundamental about the commonality of life in the cosmos.
Bio: Tony Darnell is the owner of Deep Astronomy website and a host for the same hangout channel in Youtube. He has worked in the field of astronomy all my life, his first job was at a school district planetarium in Boulder, Colorado. With the exception of a stint in the Army in the 1980’s he has worked in many aspects of astronomical research.
Most of his time has been spent writing software to retrieve, process and analyze data taken from telescopes. He has worked with data from some of the world’s largest ground-based and space-based telescopes: from the four meter Blanco telescope in Chile to the Hubble Space Telescope.
Astronomy education has always been his passion and he has written articles for DeepAstronomy.space website and produce astronomy videos for YouTube on the DeepAstronomy channel.
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Transcript:
Request for both habitable and inhabited worlds beyond earth is key to our understanding of the potential for life in the universe Our ongoing search seeks to answer very profound questions. Are we alone? How unique is our earth?
Should the hunt for life beyond earth uncover a multitude of habitable worlds and few if any inhabited ones Humanity would begin to understand just how lonely and fragile our situation is On the other hand if our hunt yields a true diversity of inhabited worlds Then we would learn something fundamental about the commonality of life in the cosmos But how will we recognize a distant habitable world? And how would we know if this environment hosts some form of life a?
a Key opportunity for understanding the remote characterization of habitability and life comes from studying our own planet Earth will always be our best example of a habitable and inhabited world Thus by studying our planet within the context of exoplanet exploration We can develop ideas Approaches and tools suitable for remotely detecting the signs of habitability and life While habitable exoplanets are unlikely to look exactly like Earth These worlds will probably share some important characteristics with our own including the presence of oceans clouds surface irregularities and potentially life Of course earth is not a static place Life emerged on our planet into an environment completely unlike the earth we understand today the early evolution of our planet was an intimate coupling between life and Geophysical processes and produced a world seeming alien to modern earth Ranging from ice-covered snowball earth scenarios to the hazy oxygen-free atmosphere of the Archean period Each evolutionary stage of our planet offers a unique opportunity to understand habitable life-bearing worlds distinct from the present earth So as we embark on our search using spacecraft like the Kepler k2 space telescope the transiting exoplanet survey satellite and later the James Webb Space Telescope Let’s ask What would earth look like from far away? using these observatories Let’s restrict the answers to looking at only stars like our Sun Although it is entirely possible to have a habitable planet like earth around other types of stars such as red dwarfs From Kepler k2 Since it is designed to look for tiny dips in brightness as the planet passes between the space telescope and the star Earth would appear as a small decrease in brightness The dip would be very specific and smaller than if a planet like say Jupiter passed in front and this dip would reappear about every 365 days or so Kepler would then tell us looking at its one spot in the constellation Cygnus That a possible rocky world about the size of the earth passes in front of its star every 365 days or so Just like our planet does The transiting exoplanet survey satellite or TESS would see something similar The main difference here is that TESS would look at almost the entire sky for two years And when it is done Astronomers hope to gather thousands of candidate earth-like planets around some of the nearest stars to us Neither TESS nor Kepler k2 can tell us much else about what earth would look like from far away To get more information.
We need more instruments specifically Spectrographs that can analyze the light passing from the host star Through the atmosphere of the exoplanet as it passes in front The James Webb Space Telescope will do exactly that It will have on board an instrument called near spec the near infrared Spectrometer which will analyze the light that has passed through any atmosphere that might be there and tell us what’s in it JWST would see a faraway earth that not only had an atmosphere But also contained elements that could harbor life What JWST sees though does not necessarily have to be the elements in the atmosphere of the earth of today When life formed on earth it was a very different place One that was quite inhospitable for us now But was obviously quite conducive to starting life from scratch There were varying amounts of water Methane carbon dioxide and ozone in the earth’s atmosphere throughout earth’s four and a half billion year history Astronomers have built many models that tell us what to expect when we try to locate earth from far away and from different periods in Earth’s history We want to know how many worlds like ours are out there Are we the only earth? Or are planets like ours common throughout our galaxy? With these models and the observations of our newest and best orbiting space observatories We are on the threshold of getting the answers to these profound questions
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365 Days of Astronomy
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