Olbers paradox

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Olbers paradox Why is the sky dark at night?
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• Olbers paradox
• Why is the sky dark at night?
• if the Universe is infinite and filled uniformly
  with stars, there must be a star in every
  direction you can look. So the sky should be as
  bright as the surface of a star.

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• Olbers paradox
• Why is the sky dark at night?
• If the Universe is infinite and filled uniformly
  with stars, there must be a star in every
  direction you can look. So the sky should be as
  bright as the surface of a star.
• But the sky is rather black at night. Most lines
  of sight do not seem to end on a star.

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• Olbers paradox
• Why is the sky dark at night?
• If the Universe is infinite and filled uniformly
  with stars, there must be a star in every
  direction you can look. So the sky should be as
  bright as the surface of a star.
• But the sky is rather black at night. Most lines
  of sight do not seem to end on a star.
• In its simplest form, Olbers paradox arises
  because, if the Universe were infinite, static
  and uniformly filled with stars, the sky would be
  as bright as the surface of the stars, clearly in
  contradiction with our experience. At least one
  of these assumptions about the nature of our
  Universe has to be wrong.
• Probably the most general way of expressing the
  significance of this observation is that the
  Universe must, in some sense, be far from
  equilibrium, though the way in which it is in
  disequilibrium cannot be deduced from this very
  simple observation. The fact that the Universe is
  expanding and has a finite age are two
  contributions to the resolution of the paradox.

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Astronomy is Astrophysics is Cosmology
is Space Science is Astrology is
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Astronomy is, broadly speaking, the observation
of the motion and distribution of celestial
objects. Astrophysics is the application of
physics to astronomy. Cosmology is the study
of the Universe as a whole, its origin,
development and fate. Space Science is
concerned with space exploration, including
putting people in space. Astrology is an
attempt to predict the future based on the
positions of the stars and planets. Is this
mumbo-jumbo, or should we respect personal or
religious views?
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Ursa Major
The Planets in January http//www.schoolsobserva
tory.org.uk/news/month.php?year2009month1
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Ursa Major
The Planets in January http//www.schoolsobserva
tory.org.uk/news/month.php?year2009month1
The pointer stars
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Ursa Major
Polaris, the North Star
The Planets in January http//www.schoolsobserva
tory.org.uk/news/month.php?year2009month1
The pointer stars
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Ursa Major
Polaris, the North Star
Cassiopeia and the Andromena Nebula, M31
The Planets in January http//www.schoolsobserva
tory.org.uk/news/month.php?year2009month1
The pointer stars
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• In 1925 Hubble showed that the Andromeda nebula
  was a collection of stars (i.e. a galaxy) outside
  and quite distinct from our own Milky Way galaxy.

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• In 1925 Hubble showed that the Andromeda nebula
  was a collection of stars (i.e. a galaxy) outside
  and quite distinct from our own Milky Way galaxy.
  
• The Andromeda nebula, M31, is another galaxy like
  our own, the Milky Way, containing some 1011
  stars.

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• In 1925 Hubble showed that the Andromeda nebula
  was a collection of stars (i.e. a galaxy) outside
  and quite distinct from our own Milky Way galaxy.
  
• The Andromeda nebula, M31, is another galaxy like
  our own, the Milky Way, containing some 1011
  stars.
• The oldest light the unaided eye can see the
  furthest back in time you can look for yourself.

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• In 1925 Hubble showed that the Andromeda nebula
  was a collection of stars (i.e. a galaxy) outside
  and quite distinct from our own Milky Way galaxy.
  
• The Andromeda nebula, M31, is another galaxy like
  our own, the Milky Way, containing some 1011
  stars.
• The oldest light the unaided eye can see the
  furthest back in time you can look for yourself.
• It has taken 200 thousand years for that light o
  reach your eyes!!!!!!

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Orion, The Hunter, constellation or a pattern of
stars. They are not a group of stars and so only
have this pattern when viewed from the earth
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On the western heel of Orion, the Hunter, rests
brilliant Rigel. In classical mythology, Rigel
marks the spot where Scorpio, the Scorpion stung
Orion after a brief and fierce battle. Its Arabic
name means the Foot. A heavy star of 17 solar
masses, Rigel is likely to go out with a bang
some day, or it might become a rare oxygen-neon
white dwarf.
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Betelgeuse is an M1 red supergiant, 650 times the
diameter and about 15 times the mass of the Sun.
If Betelgeuse were to replace the Sun, planets
out to the orbit of Mars would be engulfed!
Betelgeuse (pronounced beetle juice by most
astronomers) derives its name from an Arabic
phrase meaning "the armpit of the central one."
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Betelgeuse is an M1 red supergiant, 650 times the
diameter and about 15 times the mass of the Sun.
If Betelgeuse were to replace the Sun, planets
out to the orbit of Mars would be engulfed!
Betelgeuse (pronounced beetle juice by most
astronomers) derives its name from an Arabic
phrase meaning "the armpit of the central one."
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The Ultra Deep Field observations began Sept. 24,
2003 and continued through Jan. 16, 2004. The
telescope's ACS camera, the size of a phone
booth, captured ancient photons of light that
began traversing the universe even before Earth
existed and when the cosmos was between 1 and 2
billion years old. Photons of light from the very
faintest objects arrived at a trickle of one
photon per minute, compared with millions of
photons per minute from nearer galaxies.
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Discussion The hot big bang Imagine running a
film of the Universe backwards all matter and
energy were originally in a very, very dense
state. All exploded outwards the Big Bang (Fred
Hoyle coined this name, intending it to be
derisive). What happened before the Big Bang? 
Space-time was created at the Big Bang so many
cosmologists argue that the question has no
physical meaning. At the present time (2005) the
overwhelming weight of evidence favours the Hot
Big Bang theory. There are 3 independent pieces
of evidence
Time
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• the observed expansion of the Universe
• the Cosmic Microwave Background (CMB) radiation
• the cosmic relative abundance of the light
  elements (created by the Big Bang, rather than
  subsequently in stars or supernovae).

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This diagram shows how we come to estimates of
the age of the Universe.
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• the observed expansion of the Universe
• the Cosmic Microwave Background (CMB) radiation
• the cosmic relative abundance of the light
  elements (created by the Big Bang, rather than
  subsequently in stars or supernovae).

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• the observed expansion of the Universe
• the Cosmic Microwave Background (CMB) radiation
• the cosmic relative abundance of the light
  elements (created by the Big Bang, rather than
  subsequently in stars or supernovae).

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The Keyhole or Carin Nebula
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Gas Pillars in the Eagle Nebula (M16) Pillars of
Creation in a Star-Forming Region
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http//videos.howstuffworks.com/hsw/21363-savage-s
un-the-birth-of-stars-video.htm The Birth of Stars
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http//uk.youtube.com/watch?v1IKjgmIDeBU How
big are the planets and stars??????
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A violent and chaotic-looking mass of gas and
dust is seen in this Hubble Space Telescope image
of a nearby supernova remnant. Denoted N 63A, the
object is the remains of a massive star that
exploded, spewing its gaseous layers out into an
already turbulent region.
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This image of Centaurus A shows a spectacular new
view of a supermassive black hole's power. Jets
and lobes powered by the central black hole in
this nearby galaxy are shown by submillimeter
data (colored orange) from the Atacama Pathfinder
Experiment (APEX) telescope in Chile and X-ray
data (colored blue) from the Chandra X-ray
Observatory.
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Critical density Observation has yet to pin down
the actual density with sufficient precision to
decide if our Universe has a density larger or
smaller than the predicted critical density.
 (The critical density is the demarcation between
an open and closed Universe) Discussion Missing
mass and dark energy According to the standard
cosmological model, the Universe consists of
three categories of mass/energy. Dark matter
(25), dark energy (70) and a smattering of
normal matter (5). Dark matter was invented to
account for the observed rotational shape of
galaxies. Dark energy has been invented more
recently to account for the latest red shift
data. (As of 2005) at the highest red shifts the
Universe seems to be accelerating!
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