The Vast-beyond-Vast Size of the Universe
(Top Posts - Science - 072603)

A perspective on the size of the universe...

If the entire solar system were reduced to the size of a grain
of sand, our Milky Way galaxy would be *21 kilometers*
across and our nearest big galaxy, Andromeda, would be
*483 kilometers* away. The size of the observable universe,
on this scale, would be *over 4 million kilometers*.

A quote from -Imagining the Universe: A Visual Journey- ...
"Although the universe may be finite, it is unbounded. No
matter where one is, one appears to be at its center. We
cannot talk usefully about what lies beyond the limits of
the universe, because space itself can only be defined by
the matter it contains. As to what matter space does contain
there is great mystery. Most of the matter in space--perhaps
90 percent of it--is invisible."

Update (July 23, 2003): Dark energy's rush to turn off universe
Excerpt: "... a mysterious force called dark energy ... is
pushing the universe apart, faster and faster. Only 4 per
cent of the universe is made up of the ordinary material
of planets and stars. Another 26 per cent is invisible dark
matter. The remainder [70 percent] is dark energy. ... Dark
energy is the big mystery in physics right now. It's the most
important thing in the universe, as there's more of it than
anything else. ... The team revealed the imprint of dark
energy by combining their map of millions of galaxies with
findings from NASA's Microwave Anistropy Probe. NASA
scientists last February produced a map of the universe
a mere 380,000 years after the Big Bang 13.7 billion years
ago. ..."


Radius of the Earth = 6,400 kilometers

Distance to the Moon = 400,000 kilometers

Distance to the Sun = 150,000,000 (150 million) kilometers

Distance to Pluto = 6,000,000,000 (6 billion) kilometers

Distance to Proxima Centauri (our nearest star apart from
the sun) = 40,000,000,000,000 (40 trillion) kilometers

Number of stars in the Milky Way galaxy =
most estimates have the figure pegged at
400,000,000,000 (400 billion)

Distance to Sirius (the brightest star in the
sky) = 80,000,000,000,000 (80 trillion) kilometers

Size of the Milky Way galaxy =
450,000,000,000,000,000 (450 quadrillion) kilometers

Number of galaxies similar to the Milky Way galaxy
in the universe = over 100,000,000 (100 million)

Number of galaxies in the universe (total of all
kinds) = over 80,000,000,000 (80 billion)

Number of stars in the visible universe (total of
all kinds) = over 70,000,000,000,000,000,000,000 (70 sextillion)

Distance to the Andromeda galaxy, the nearest
big galaxy (to the Milky Way galaxy) =
21,000,000,000,000,000,000 (21 quintillion) kilometers

The Milky Way and Andromeda galaxies are part of
the "local" galaxy cluster of about 30 galaxies, the
size of which is =
30,000,000,000,000,000,000 (30 quintillion) kilometers

The size of the observable universe =
180,000,000,000,000,000,000,000 (180 sextillion) kilometers

- - -

Numeric reference chart:

1 kilometer = 0.62 miles

American system used for large numbers:

million ... number followed by 6 zeroes
billion ... number followed by 9 zeroes
trillion ... number followed by 12 zeroes
quadrillion ... number followed by 15 zeroes
quintillion ... number followed by 18 zeroes
sextillion ... number followed by 21 zeroes