Download Defining the Question - SwRI

ET Life
●
Pick up a syllabus and calendar (if you didn't)
●
Class Webpage – I will put up notes
http://www.boulder.swri.edu/~kretke/astr3300
●
Textbook will be on reserve in Library next
week. If you need access to a book before
then, talk to me after class.
– News Blurb –
New Meteorite from Mars!
●
Meteorite in fell in July
●
Found In Morocco
●
Igneous Rock
●
http://blogs.nature.com/news/2012/01/morocco-fireball-yields-rare-mars-meteorite.html
“Why are you taking a class on
extraterrestrial life?”
Small Group Discussion
Question: You are meeting with Jared Polis,
Micheal Bennet and Mark Udall. Which (if any) will
you tell them we should spend more money on:
●
looking for planets elsewhere,
●
listening for civilizations to contact us,
●
understanding diversity of life on earth,
●
looking for life in the solar system?
Why?
Definition of ET Life?
●
●
●
“Biology has gotten along quite nicely without
specifically saying what it is studying.”
– David Darling “Life Everywhere”
“I know it when I see it.”
– Justice Potter Stewart,
referring to obscenity
(1964)
Something “easier” – What is a planet?
Should Pluto be a planet?
Wandering Stars
asteres planetai
ἀστέρες πλανῆται
“Planets”
●
Prehistoric: Mercury, Venus, Mars, Jupiter, Saturn
●
Earth – Copernicus mid-1500s
●
Uranus – 1781
●
Ceres – 1801
●
Pallas – 1802, Juno – 1804, Vesta – 1807
●
Neptune – 1846
●
Pluto - 1930
●
Eris - 2005
IAU Definition
(1) A "planet" is a celestial body that: (a) is in orbit around the
Sun, (b) has sufficient mass for its self-gravity to overcome
rigid body forces so that it assumes a hydrostatic equilibrium
(nearly round) shape, and (c) has cleared the neighbourhood
around its orbit.
The IAU therefore resolves that planets and other bodies in
our Solar System, except satellites, be defined into three
distinct categories in the following way:
(2) A "dwarf planet" is a celestial body that: (a) is in orbit
around the Sun, (b) has sufficient mass for its self-gravity to
overcome rigid body forces so that it assumes a hydrostatic
equilibrium (nearly round) shape, (c) has not cleared the
neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall
be referred to collectively as "Small Solar System Bodies".
What about Extrasolar Planets?
Homework
●
●
●
For Monday: Read Chpt 2.1-2.3
Homework due next Friday will be posted on
the website by Monday.
If you haven't emailed me and Becky your
answer to: Why did you decide to take a course
on ET Life do so before Monday or risk being
dropped from the course as a no show!
Movie Link
●
Powers of Ten
http://www.youtube.com/watch?v=qxXf7AJZ73A