1) The document discusses the search for life beyond Earth, including potential locations in our solar system like Mars and moons of Jupiter, as well as exoplanet detection methods like observing atmospheres and the radial velocity technique. 2) It describes early SETI projects like Ozma that searched for radio signals from nearby stars, as well as more recent developments like the Arecibo message and Drake Equation that estimate the probability of intelligent life elsewhere. 3) While the discovery of exoplanets and evidence for simple life on places like Europa make the existence of life in the galaxy more likely, the document notes it is very difficult to estimate how often life might evolve to become intelligent like humans.

1. Are we Alone? - The Search for Life
beyond the Earth.
Ian Morison
Emeritus Professor of Astronomy
Gresham College

2. Star-stuff

6. Ring
Nebula

7. M1
The
Crab
Nebula

8. Elsewhere in our own Solar
System
We could find other simple life-forms
here.

9. Canals on
Mars?

10. The Face on Mars!

13. Valleys and Volcanoes

14. Olympus Mons

15. Islands and
Channels

16. Viking on Mars
• Two Viking Spacecraft landed on Mars in 1976 to search
for evidence of life.

17. Spirit and Opportunity

18. Martian Dust Devils

19. Phoenix Lander

20. Jupiter
Io
Europa
Callisto
Ganymede
4 major moons – discovered
by Galileo

21. Io

23. Jupiter’s Moon Europa

24. Breaking up of the surface
• Icebergs!

25. Water Plumes!

26. Searching for Life!

27. Finding Evidence of Simple Life
on other Planets

28. Can we see any exo-planets?
A real problem due to the
overwhelming brightness of the star
orbited by the planet.

29. Infrared observations by one of the
KECK telescopes

30. HR 8799 with
three planets

31. HST using a coronograph
• The Hubble Space
Telescope has
observed a planet in
orbit around the star
Formalhaut.

33. Indirect Detection Methods
The RADIAL VELOCITY or
DOPPLER WOBBLE method

36. 51 Pegasi b
• The first planet
detected around a
normal star.
• Period just 4 days!
• A gas giant very close
to its star.

37. Planetary Transits
Detect the transit of a
planet as it crosses
the face of the star.
This results in a
slight drop in
luminosity.
This can only work
if the orbital plane of
the planet includes
the Earth.

38. HD 209458 transit

39. HD 209458 b
• 150 light years
from Earth.
• Planet orbits
every 3.5 days.
• 4 million miles
from its star.
• Atmospheric
temperature
~2000K.

40. Evidence for Life?

41. We could detect evidence of life by
observing the spectra of the planet’s
atmosphere.

42. Study the Infra-Red Spectrum

43. What does it tell us?

45. SETI
The Search for Extraterrestrial
Intelligence

46. The Seminal Paper
• In 1959 Giuseppe Cocconi and Phillip Morrison published
a paper in Nature in which they pointed out that given two
telescopes of the size of the newly built 250ft Mk1 Radio
Telescope at Jodrell Bank it would, in principle, be
possible to communicate across inter-stellar distances.

47. Where to look? Locations
• They suggested that any
search should target the
nearest Sun-like stars as
these live long enough and
are hot enough to allow life
a chance to evolve on a
planet at a suitable distance
from them.
• A target list was provided including Tau Ceti and
Epsilon Eridani.

48. Where to look? Frequency
• They pointed out that the background noise (atmosphere,
Galaxy, CMB etc.) was a minimum between ~1 to 10 GHz.
• This band included the (radio) Hydrogen Line at 1.4 GHz
and the OH Lines at ~ 1.6 GHz.
• The band from 1.4 to 1.6 GHz is called the Water Hole

49. Project Ozma
• In 1960 Frank Drake and his colleagues at Green Bank,
West Virginia, used the Tatel 85ft telescope to make the
very first SETI observations in what was called Project
Ozma.

50. Project Ozma
• They were given use of a new, state of art, low noise
parametric amplifier and made observations over a 400
KHz band around the Hydrogen Line at 1420 MHz.
• They observed Tau Ceti and Epsilon Eridani for a total of
two months, but only detected the, then top secret, U2 Spy
plane!

51. The Voyager Record

52. Numbers and
DNA

53. Continental
Drift

54. Birth

55. Arecibo Radio Telescope

56. Arecibo Message

57. How does what we have learnt about
other planetary systems affect the
likelyhood of other life being present
in our galaxy?

58. The Drake Equation

59. Number of Stars born per year in
the Milky Way
• Recent estimate of current SFR = 7
stars/yr

60. Fraction of Sun-type stars
• ~73-84% of the stars in
the Milky Way are M
type – too cool
• Upper limit of 21% of
stars in the Milky Way
are like our Sun.

61. So about 1 suitable star is born
per year

62. Fraction of Sun-type Stars with
Planets
• We do not yet know.
• As time goes by we will be
able to detect many more.
• There may be 10-30% of
stars with planetary systems.

63. Fraction of stars with terrestrial
planets within their solar systems
• Again we do not know – but
we are finding many solar
systems where we do NOT
believe there can be Earth-
Like planets.
• Hopefully this is because
solar systems like ours are
rather hard to find!

64. Number of Planets in a Star’s
Habitable Zone
• 8 planets; many satellites
• Earth, Mars; (Europa)

65. Fraction of habitable planets where
life arises
• Wild optimism: the
fraction where life arises
= 100%

66. Simple Life could be very
common.

67. How often will simple life evolve
into intelligent life?
This, in my view is the most difficult
part of this equation to estimate.

68. • Our Moon has
stabilised our
rotation axis
Its formation
gave us a
thinner crust.

69. • Recycling of CO2

71. COMETS

72. Fraction inhabited by intelligent
beings
• One needs, we believe,
a very long time to
allow life to evolve.
• Really difficult to
estimate how often a
planet will have a
temperate climate for
long enough

73. Perhaps our human race is rather
special.