ASTR1001%20%20%20Assignment%204:%20Background%20Briefing

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ASTR1001 Assignment 4 Background Briefing
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The Planet Zog

• Imagine that you live on the distant planet Zog
  far away in a space-time very different from our
  own. Zog is very much like the Earth you have a
  technology virtually identical to our own. All
  the laws of Physics, as you measure them in the
  Zoggian laboratories, seem identical to the laws
  we measure on Earth.
• The one thing that is very different is the night
  sky...

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The stars look similar to Earths, but there is
no Milky Way.
Instead, north Zog astronomers see the awesome
sight of the Greater Milkstain
With its brilliant off-centre blue spot.
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Southern hemisphere Zog astronomers see the
equally brilliant southern blue spot.
Recent Bubble Space Telescope observations have
shown that the southern blue spot also has an
off-centre milkstain associated with it. But the
Southern Milk Stain is very very much smaller and
fainter than its northern counterpart.
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Celestial Coordinates.

• The two blue spots are diametrically opposite on
  the sky (and hence can never both be seen at the
  same time, except by astronauts).
• They are used as the origin of the celestial
  coordinate system

Declination 90 for northern blue spot, 0 for
the celestial equator.
Both milkstains extend away from the two blue
spots in the same direction (though the GMS
extends further).
Right Ascension 0 to 360. Zero axis is along the
long axis of the two milkstains.
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The Milkstains

• The Greater Milkstain (GMS) has been known for
  centuries to break up into literally millions of
  stars when viewed with even a pair of binoculars.
  There appear to be about ten millions stars in
  total.
• The Lesser Milkstain (LMS) does not break up into
  stars when observed with telescopes. It does,
  however, have some rather curious jet-like
  features emerging from it

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The Fuzzballs

• In addition to stars, some curious fuzzy objects
  are seen scattered, with roughly uniform number
  density, all around the sky. They are similar to
  the jet-like features extending from the Southern
  Blue Spot (SBS). They vary enormously in
  brightness and size, though the larger ones tend
  to be brighter. Faint fuzzballs greatly outnumber
  the bright ones. Most fuzzballs are brighter and
  bigger than the LMS.

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The Blue Spots

• Both blue spots are roughly equally bright. They
  do not vary in brightness. Both are about as
  bright as a full moon. They are not just dots
  they seem to consist of blue-white cores,
  surrounded by a paler fuzz that merges into the
  two Milkstains.