Transcript Are we alone

“The universe is not only queerer than we suppose, but
queerer than we can suppose” J.B.S. Haldane
Astronomy and Religion
 In 1600, the Italian philosopher, Giordano Bruno
was burned at the stakes because he maintained
the "heretical" notion that there were countless
other worlds out there containing life.
 In the 18th century, the pendulum shifted to the
other extreme; many astronomers were convinced
that every star had planets with life. Will Herschel
(the man who discovered Uranus), even speculated
that the sun was populated with life.
Church vs. Science
 The possibility of life on other planets is another topic
which creates great debate between scientists and
religious beliefs.
 Once again Old Testament biblical teachings tell us
that one God created man in his image and all life on
Earth.
 Would our Christian values be shaken by the presence
of life on other worlds? What about intelligent,
sentient life?
 How does the Catholic Church respond?
The Catholic Churches View
 The following are thoughts from Vatican Astronomer
and U.S. Jesuit Brother Guy Consolmagno with the
help of the British-based Catholic Truth Society in
2005. (The following quotes were taken from his
interview with the Catholic News Service).
 "What Genesis says about creation is true. God did it;
God willed it; and God loves it. When science fills in
the details of how God did it, science helps get a flavor
of how rich and beautiful and inventive God really is,
more than even the writer of Genesis could ever have
imagined”
The Churches View
 The limitless universe "might even include other
planets with other beings created by that same loving
God," Consolmagno added. "The idea of there being
other races and other intelligences is not contrary to
traditional Christian thought.
 "There is nothing in Holy Scripture that could confirm
or contradict the possibility of intelligent life
elsewhere in the universe," Consolmagno wrote.
The Churches View
 More recently, Father José Gabriel Funes, an Argentine
Jesuit, told the Vatican newspaper: "Just there is a
multiplicity of creatures on earth there could be other
beings, intelligent ones, created by God.“
 However the Jesuit astronomer went on to speculate that if
intelligent beings exist in another solar system, "they might
have remained in full friendship with the Creator," and
thus might not require salvation as the human race does.
What conditions make Life on Earth Unique?
What Makes Earth Special?
 Planet Earth is the only known host for life, but we
have now gained the technology to search other
worlds within our own system and to locate planets in
other systems.
 Is life unique on Earth or is life common throughout
the ? What do you think? Let’s poll the class for
opinions. What are the reasons given for their
opinions?
 Let us start by defining the special circumstances that
allow for life on Earth.
Video Introduction
 Let’s watch these videos to get an idea of the
astronomical and Biological requirements for life:
 Video: A Teacher’s Guide to: What makes Life on Earth
Possible?
http://www.youtube.com/watch?v=1zCQ7QM3CZU
 IMAX: The Secret of Life on Earth
http://www.youtube.com/watch?v=CRkGb7inQ5I
1.
Temperature (The Habitable Zone)
and the presence of Water!
 A stars habitable zone is defined as the region in which
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orbiting planets could be habitable (contain life.
The most important factor is temperature.
Since life as we know it requires water on its surface,
temperatures must be between 0 and 100°C somewhere on
the surface.
All the chemical reactions of life occur in aqueous
conditions – in other words with chemicals dissolved in
water!
High temperatures cause proteins/DNA to degrade. These
are the molecules of life. Very low temperatures mean that
chemical reactions (including biological reactions) occur
slowly.
The Habitable Zone
The Habitable Zone
 Habitable zones vary for
each star system. At right,
the conservative and
optimistic habitable zones
for our Solar System.
2.
The Effect of Gravity
 A planet (or moon) must have enough mass to have
substantial enough gravity to maintain an
atmosphere. Mercury and the moon, despite being
massive enough to be spherical, are not massive
enough to keep an atmosphere.
 Similarly, too much gravity may crush possible life.
3.
An atmosphere
 Volcanic activity furnished Earth with
an early atmosphere. Though this
atmosphere did not contain oxygen gas,
it supplied the chemicals of life –
carbon (in the form of CO2), nitrogen
(in the form of ammonia NH3), oxygen
and nitrogen in the previous
compounds and a wide variety of
important metals and non-metals in
abundance.
 An atmosphere is often required to trap
heat and to maintain stable surface
temperatures.
 Atmosphere’s also provide protection
against smaller meteorites.
Atmospheres and Surface Temperatures
Atmospheres and Surface Temperatures
3.
Atmosphere
(Protection from Meteor Bombardment)
 Many astrobiologists
have suggested that life
took hold on the surface
of Earth several times
only to be exterminated
by a massive meteor
bombardment in each
case.
 Once Earth orbited in a
clearer path, life was able
to take hold permanently.
4.
A Magnetic Field
 A magnetic field is required to protect an
atmosphere from being blown away by the
forces of the solar wind.
 The solar wind is a flow of radiation and
charged particles emanating from a star.
These particles can interact with the
particles in a planetary atmosphere and
slowly remove it.
 A magnetic field can be created by a
molten, spinning iron core (like Earth) or
by a rotating charged metallic layer like
that seen in the Gas Giant planets.
 We know that a planet’s age and size can be
a factor. Mars was large enough to
maintain an atmosphere, but its liquid core
“froze” and its magnetic field was lost!
5.
A Stable Climate (Axial Tilt)
 Wildly fluctuating temperatures and
sudden changes of climate do not allow
living things to adapt.
 It is thought that the Earth’s very small
wobble on its rotational axis keeps
these climatic changes to a minimum.
 Remember that this wobble is
significantly lessened by the presence
of our large moon and its gravitational
influence.
 Similarly, an orbit with low eccentricity
will result in a much more stable
climate.
6.
A Stable Medium Sized Star
 Our sun has released radiation with little
variation in its quantity for billions of
years. This stability is critical for Life on
Earth.
 A star whose energy output was variable
would have a wildly changing habitable
zone and life could not take hold.
 Large bright stars burn out very quickly
and would not leave much time for life to
take hold.
 Small dim stars have been suggested as
possible hosts for planets with life but
these planets would have to obit vey close
to their stars.
7.
Location in the Galaxy
 The Sun location in the “galactic
suburbs” of the Milky Way
Galaxy is fortuitous.
 The cores of most galaxies
contain a much higher density of
stars and such high energy
objects as black holes and
quasars. The intense radiation of
these regions would likely strip
away the atmosphere of any
planets and bake their surfaces.
 Our search for exoplanets occurs
in the “Galactic Habitable Zone”
8.
Availability of heavy elements.
 Earth has an abundance of
heavy elements – many of
which are found within
complex living organisms.
 Earth must have been formed
in a region of space where its
protoplanetary disk formed
from a nebula that contained
heavy metals. This is only
possible if the nebula was
produced near a supernova (the
only source of elements heavier
than iron)
9.
Plate Tectonics
 A geologically active planet
will have moving tectonic
plates (crust).
 This process creates volcanic
activity which releases gases
such as CO2 and recycles
elements that get trapped in
the crust.
 Early life is likely to have
formed around hydrothermal
vents. Life used the heat
energy and abundance of
chemicals to sustain life
functions.
10. Time for Evolution
 The process of evolution is very slow. It took nearly 4
billion years for life to develop past the single-cell stage!
It has been 600 million years since the first explosion of
multi-cellular life.
 Short lived stars and planets that lose their atmosphere
too quickly are not suitable for the development of
complex life.
The Drake Equation
 The Drake Equation was developed by Frank Drake in
1961 as a way to focus on the factors which determine
how many intelligent, communicating civilizations
there are in our galaxy.
The Drake Equation
 The Drake Equation is: N = R* fp ne f1 fi fc L
 It depends on seven factors
 R* = The number of suitable stars form each year in our galaxy.
 fp = the fraction of these stars that have planets
 ne = the number of these planets suitable for life
 f1 = the fraction of these planets that develops intelligent life
 fi = is the fraction of these life forms that develop intelligence.
 fc = is the fraction of these intelligent life forms that choose to
communicate with other civilizations.
 L = the lifetime of such as civilization.
 One of the problems of this equation is that it cannot be calculated
with any certainty since no accurate value can be determined for any
of the 7 variables.
 However, it gives us a good framework to estimate the probability of
alien life.
The Drake Equation
 Drake’s calculation for our Galaxy based on data from his time
period:
N = R* fp ne f1 fi fc L
= 5 x 50% x 2 x 100% x 20% x 100% x 10 000
= 10 000 possible civilizations in our galaxy.
The Drake Equation
o SETI (Search for Extra-Terrestrial Intelligence) gives the following
data:
R* = The number of suitable stars form each year in our galaxy = 100 billion
fp = the fraction of these stars that have planets = 20 to 50%
ne = the number of these planets suitable for life = 1 to 5
f1 = the fraction of these planets that develops intelligent life = 0 to 100%
fi = is the fraction of these life forms that develop intelligence = 0 to 100%
fc = is the fraction of these intelligent life forms that choose to communicate
with other civilizations = 10 to 20%
 L = the lifetime of such as civilization = 100 to 10000
 N=?
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o Go to the SETI website to calculate your own value!
http://www.activemind.com/Mysterious/topics/seti/drake_equati
on.html
What about Extraterrestrial Life?
 Evidence that life could exist on other worlds:
1. Amino Acids the building blocks of life
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These have be formed in a lab in simulated primitive
atmospheres.
The Miller-Urey Experiment (The Primordial Soup).
Watch
http://www.youtube.com/watch?v=mF9U5x6Nxnw
The conditions of this experiment have since been
determined to be dissimilar to the actual conditions of the
early Earth.
The term abiogenesis is used to describe the development
of living organisms (or life processes) from inorganic
compounds and abiotic conditions.
Amino acids have been found in meteorites. This suggests
that life might have been carried to Earth from “outer
space”, a theory called Panspermia.
What about Extraterrestrial Life?
2. Extremophiles
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Micro-organisms adapted to environments once thought so
extreme that life could never exist there in any form.
Examples
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Light and Oxygen-free environments like the bottom of the
ocean
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No sun-light environments like caves
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Acidic environments like around “Old Faithful” in
Yellowstone National Park.
Many biologists believe that the first living organisms on our
planet lived in these extreme conditions (on an Early Earth
that was very hostile to life)
Extremophiles - Hydrothermal Vents
 http://www.youtube.com/watch?v=XotF9fzo4Vo (2:52
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Nat Geog)
http://www.youtube.com/watch?v=5JzUgi6YNlY (4:00
Evolution of Life on Earth)
http://www.youtube.com/watch?v=2FFnrW_SUdM
(4:42 - no audio, music only, great video footage)
http://www.youtube.com/watch?v=BRqrT_rHvAw
(8:45 - extremophiles)
http://www.youtube.com/watch?v=qtLJzsRYvaI&index
=1&list=PL1HikUR5c27lxTOv9mU3HzLe8dfM3wAln
(4:56 - extremophiles)
Possibility of Life in Our Solar System
Given that life can form in extreme environments - it is
thought life could exist in extreme environments
elsewhere in our solar system.
Extremophiles also hint at the development of life on
Earth.
Here are the top five solar objects in our solar system
that might be able to support life:
5. Io
 Jupiter’s moon Io is one of the few solar
system moons to support an
atmosphere, and it contains complex
chemicals promising for life.
 Volcanism on the moon also makes it
warmer than many other.
 Io is still a long shot, though, because
its location inside Jupiter’s magnetic
field means it is constantly being
pelted with lethal radiation.
 Its violent surface also seems
inhospitable, with temperatures often
too cold to support life, as well as
molten hot spots that are equally
deadly.
4. Titan
 Saturn’s largest moon looks
suspiciously like it might have
hosted life, because its thick
atmosphere is rich in compounds
that often mark the presence of
living organisms.
 For instance, Titan’s air is filled
with methane, which is usually
destroyed by sunlight. On Earth,
life constantly replenishes
methane, so it might similarly be
responsible for the methane on
Titan. Titan is rather cold,
however, and if liquid water
exists, it must be deep beneath
the frozen surface.
3. Mars
 The red planet is the most
Earth-like of solar system
planets, with a comparatively
similar size and temperature
range as our own planet.
 Large bodies of water ice lie on
Mars’ poles, and there’s a
reasonable chance of liquid
water beneath the surface.
 The thin atmosphere on the
planet is not strong enough to
shield the planet against lethal
solar radiation, though microbes
could potentially exist beneath
the surface.
2. Europa
 Jupiter’s moon Europa also seems a
possible stomping ground for E.T.
due to its potential water and
volcanic activity.
 Though the surface seems to be
frozen, many suspect that buried
underneath is an ocean of liquid
water.
 Microbial life could potentially
survive near hydrothermal vents on
Europa, as it does on Earth.
1. Enceladus
 The sixth-largest moon of Saturn has
been called the most promising
possibility for life thanks to its
welcoming temperature and the likely
presence of water and simple organic
molecules.
 The surface of the icy moon is thought
to be about 99 percent water ice, with
a good chance of liquid water beneath.
 The moon seems to have a boiling core
of molten rock that could heat the
world to the toasty temperatures
needed to give rise to life.
The Search for Other Planets
AND the Search for Extraterrestrial life
Locating Exoplanets
Video: (Exoplanets: Are there other Earths)
http://www.youtube.com/watch?v=cvET91EYoyc
(National Geographic: Alien Planets)
http://www.youtube.com/watch?v=thMCmzvoLPs
Difficulties with locating Exoplanets
1. Planets don’t produce any light of their own.
2. They are an enormous distance from us.
3. They are lost in the blinding glare from their parent
star.
Techniques for Locating Exoplanets
1. Doppler Wobble
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A star orbited by a planet will
wobble due to the gravitational
pull of the planet.
This wobble shifts the stars
absorption spectrum between
the red and blue ends.
The amount of shift allows
astronomers approximate the
planets size and mass.
The doppler shift is very small
(1/10,000,000th of a wavelength),
thus detection equipment must
be very sensitive. As a result this
technique has only been available
for a decade.
The Doppler Wobble in Action
Locating Exoplanets
2. Transits
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A planet passing in front of
a star minutely dims the
light of a star.
This allows astronomers to
measure the orbital
period, diameter and
atmosphere of the
exoplanet.
The dips in the stars
brightness are miniscule usually less than 1%
Locating Exoplanets
2. Transits
 The Kepler Space Telescope (shown below) is designed
to look for transiting planets in front of stars.
 The data from 5 exoplanets is shown below.
The Kepler Mission
 NASA has an entire website dedicated to
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the Kepler Spacecraft and its mission to
find exoplanets
(http://www.nasa.gov/mission_pages/kep
ler/overview/index.html#.VEcfOWejI6A )
The Kepler Spacecraft collects light using
a special telescope called a photometer
and has a very wide field of view (105°)
The spacecraft stares at the same small
portion of space continually for 3.5 years
and collects light continuously at over
100,000 stars.
It uses the transit method of detecting
exoplanets and needs this amount of time
to see the minute changes in light
intensity.
The Kepler Mission will soon come to an
end and will be taken over by the ESA’s
Plato mission
Locating Exoplanets
3. Astrometry
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Astrometery is a long used
technique to precisely
measure the position of a star
in the sky.
Today, planet hunters use
astrometry, they look for a
minute but regular wobble in
a star's position. If such a
periodic shift is detected, it is
almost certain that the star is
being orbited by a companion
planet.
This technique was used in
early planet hunting, but not
recently. The future SIM
mission will hunt for
exoplanets using this method.
Similar to the Doppler Wobble
Method, the star’s positional
wobble is measured except using a
star’s position vs. spectrometry.
Locating Exoplanets
4. Direct Imaging
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Blocking a star’s light has yielded images of 11 planets
Locating Exoplanets
5.
Gravitational
Microlensing
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If a star and planet pass in
front of another star, their
gravitational fields act as a
lens, bending the light
from the far star in a
distinctive way.
The lensing causes the
intensity of the star’s light
to increase (like any lens)
If a planet happens to be
orbiting the star, a slight
additional lensing effect is
added and the star shines
brighter.
Gravitational Microlensing
Gravitational Microlensing
Kepler Mission Discoveries
Kepler Mission Discoveries
Kepler Mission Discoveries
Discoveries
 As of October 2010, astronomers have found evidence
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of the existence of 490 exoplanets.
By 2014, over 2000 exoplanets have been found.
Most of these planets are much bigger than our planet
because planets our size are often too small to see at
these great distances.
The easiest planets to spot often orbit stars at very
close range, with orbital periods measured in days not
years. Transits must be fast to be noticed.
Recent work has found an increase in Earth sized
planets
Discoveries
 Most planets are thought to be similar to Jupiter (large
gas giants) but recent work has detected Earths and
Super-Earths (rocky planets with masses 10 times our
planet’s mass.
 The search for life is focused on Earth-like planets
found in stellar habitable zones - more of these planets
are coming to light.
Top 10 Exoplanets: Weird Worlds
in a Galaxy Not So Far Away
A look at some of our extreme planetary neighbors right
here in the Milky Way Galaxy from an article produced
by Adam Hadhazy for Scientific American in 2008
10. FIRST EXOWORLD:
 The first solid evidence for an
exoplanet (extrasolar planet)
came in 1992 when scientists
calculated that two bodies must
be orbiting the pulsar PSR 1257
 Distance from Earth: 978
light-years (One light-year
equals the distance light in a
vacuum travels in a year: 5.88
trillion miles, or 9.46 trillion
kilometers.)
Exoplanet Mass: 4.1, 3.8 Earths
(0.013 and 0.012 Jupiter)
TYPICAL STAR; EXTRAORDINARY PLANET
 The first exoplanet spotted
around a Main Sequence star
similar to our sun, gaseous 51
Pegasi b completes an orbit
around its host star every four
days. Many exoplanets found
after this one are very similar
"hot Jupiters," named for their
size and proximity to their star.
 Distance from Earth: 48 lightyears
Exoplanet Mass: 0.47 Jupiter
8. SURVIVOR OF APOCALYPSE:
 V392.1 Pegasi b. distinguishes itself
as the only planet known to orbit a star
that has passed through its red giant
phase. Remember when our own sun
goes red giant in about it will likely
swallow Mercury and Venus and, if it
doesn't also envelop Earth, will scorch
the planet: boiling off Earth's oceans,
eventually leaving the once-verdant
world a barren cinder.
 Distance from Earth: 4,550 lightyears
Exoplanet Mass: 3.2 Jupiters
7. POTPOURRI
OF PLANETS:
Distance from
Earth: 44 light-years
Exoplanet Masses:
Range from 18 Earths
to four Jupiters
 Astronomers discovered a fifth planet
around the sunlike star 55 Cancri in
2007, making it the most planetpopulated one outside our own--so far.
All five confirmed planets in the
system are jumbo versions of Earth
and its neighbors, including a rocky
mega-Earth and a gas giant four times
as massive as Jupiter.
6. FREAKISHLY FROZEN WORLD:
 Scientists think Gliese 436 b (aka GJ
436 b), a Neptune-size exoplanet, is
too heavy to be all gas but not heavy
enough to be entirely rock. They
surmise that in addition to gas and
rock, it also contains a kind of
pressurized, high-temperature ice that
only exists on Earth in laboratories.
 Distance from Earth: 33 light-years
Exoplanet Mass: 22 Earths (0.07
Jupiter)
5. NOT TOO HOT OR NOT TOO COLD.
 When astronomers spotted Gliese
581.C, it set off a flurry of reports
that this exoplanet fell within the socalled Goldilocks Zone. Gliese 581 c
orbits closer to its star than torrid
Mercury orbits the sun, but the host
is a dwarf star 50 times cooler than
our sun, which researchers thought
placed it in that star's habitable
zone.
 Distance from Earth: 20.5 light-
years
Exoplanet Mass: five Earths (0.016
Jupiters)
4. EXOHOTTIE:
HD 149026 b ranks as
one of the hottest
known exoplanets,
with a lead-boiling
surface temperature of
around 3,700 degrees
Fahrenheit (2,000
degrees Celsius).
Tricky measurements
of light reflecting
from its surface
suggest that this world
may be pitch-black in
color,
 perhaps because of a strangely high
concentration of heavy, metallic
elements in its atmosphere. But even
in that case, it may glow red like an
ember from all that heat. Besides its
fearsome exterior, researchers believe
this gaseous "hot Saturn" has the
largest known planetary core,
estimated at about 70 to 90 Earth
masses.
3. IT'S A SMALL(ER) WORLD:
 Besides being the first exoplanet ever
directly observed from Earth as it transited
in front of its host star, it is also shrinking.
Its proximity to the inferno of its host star
superheats the planet to an estimated
18,000 degrees Fahrenheit (10,000 degrees
Celsius), which researchers believe is
causing it to sweat off about 10,000 tons
(9,000 metric tons) of atmospheric
hydrogen every second, forming a
cometlike tail. It is thought that HD
209458 b might eventually lose its entire
atmosphere. The world was also the first
exoplanet to give up evidence of water
vapor in its atmosphere, followed by the
discovery of methane.
2. EARTH TIMES THREE:
Distance from
Earth: 1,000 light
years
Exoplanet Mass:
3.3 Earths
 The exoplanet MOA-192 b,
which orbits a purplish star in
this artist's impression, is the
smallest discovered so far,
measuring about 3.3 Earths in
mass. It revolves about a dim
star that is about one twentieth
the mass of our sun, making
this the planet with the
teensiest host star, to boot. This
star's diminutive size, however,
is quite common in the
universe, so finding that it can
sport planetary bodies
encourages researchers about
the odds of finding Earthlike
planets.
1. PRIMORDIAL PLANET:
Distance from Earth:
5,600 light-years
Exoplanet Mass: 2.5
Jupiters
 Exoplanet PSRB1620-26b is believed to have
formed an incredible 13 billion years ago, less
than a billion years after the big bang. Aptly
nicknamed Methuselah, this probable gas giant
resides in an ancient type of galaxy known as a
globular cluster, where it orbits two stellar
hosts, a dwarf star and a pulsar, both remnants
of larger stars. It is thought that Methuselah
once orbited a common yellow star like our sun,
which became a red giant, giving up its matter
to a dense neutron star--the latter of which
became a spinning pulsar in the process.
Packed in amongst other stars in the cluster,
scientists think it is likely that Methuselah has
been blasted by radiation from many
supernovae over its lifetime. It however,
indicates that a long time ago, in a globular
cluster far, far away, a world can exist.
What about Extraterrestrial Life?