A box 200 million light-years on a side, wherever in the universe, would
        contain roughly the same number of galaxies, grouped in a statistically
        similar way into clusters, filamentary structures, and so on.
         [M.J. Rees, 2000, Science 290(5498), 1919-1925].

Superclusters are large conglomerates of thousands of galaxies, with sizes of hundred of millions of light-years
        [Drinkwater, M., 2000, Science 287, 1217].

Milky Way has a diameter of about 100,000 light-years*.

        Milky Way has about 150 globular clusters, spheres of about 100
        light-years in diameter, densely packed with 10⁵ - 10⁷ stars
        [Schweitzer, F., 2000, 'Galaxy-Scale Mergers and Globular Clusters',
        Science 287 (5451), 1410].

      The Milky Way contains about 100 billion stars
[M.J. Rees, 2000, 'Piecing together the biggest puzzle of all',
Science 290 (5498), 1919-1925].

  Stars and globular clusters of the Milky Way
formed over 12 billion years ago

                            [R. Buser, 2000, Science 287 (5450), 69].

      The Sun is about 26,000 light-years from the center of the galaxy,
68 light-years from the galactic plane
which is about 1,300 light-years thick in our vicinity .

            [S. Hawking "A Brief History of Time", A Bantam Book, 1996].

At the center of the Milky Way there is supersized black hole
having a mass of  2.6 +/- 0.2 million times that of our sun
[F.Y.- Zadeh et al., 2000, Science 287 (5450), 85].

Stars are whirling around the core of the Milky Way
at speed up to 1,500 kilometers/second,
that's about 50 times faster than earth circles the sun  [E. Stockstad, 2000, Science 287 (5450), 67].

The Milky Way and Andromeda, together with 34 smaller galaxies, for a total mass of about 700 billion solar mass belongs to the small cluster of galaxies called the Local_Group.

                    [R. Buser, 2000, Science 287 (5450), 69].

The Milky Way and Andromeda
are closing the 2.5 million light-years gap between them
at a nearly 500,000 kilometers/hour.
The pace will quicken as the two galaxies approach.
They will smash within 3 billion years
[R. Irion, 2000, Science 287 (5450), 62].

The Local Group is a few million light years across; it is about 50 million light-years away from the Local supercluster [Virgo],
an archipelago of several hundred galaxies.
The Milky Way is moving around in the Local Group
at about 300,000 Km/hr.
The Local_Group is moving toward the center of the Local supercluster at about 1 million Km/hr;
the Local supercluster is moving towards the Hydra constellation
at ~ 1 million Km/hr
[W. & K. Tucker, "The dark matter", 1988, W. Morrow & Co., NY].
 
 

The present background temperature (a remnant of big-bang) is only 2.728 degrees above absolute zero; it represents a surprising amount of heat: 412 million quanta of radiation (photons) per cubic meter of the present-day universe; in contrast, all the observed stars and gas in the universe would amount to only about 0.2 atoms per cubic meter (the density of universe)
[M.J. Rees, 2000, Science 290(5498),1919-1925].

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* One light-year = distance covered by light in one year                         = ~ 9.46 x 10 ¹² km = ~10,000 billion kilometers       [300,000 km/sec *31,536,000 sec] One parsec = 3.26 light-years.

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