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08/29/2007
Cosmic Stuff
Much, or perhaps most of the time, I will find or check material
for this column in reputable scientific publications such as
Science or other journals. With it being summer and still being
in the care giving mode after my wife’s spinal surgery, I have
sunk to using the comics section of Sunday’s Star-Ledger as one
source for this column! On the last page of the “funnies” was a
panel titled “You Can” by either Jok or Jax Church. I’m
uncertain as to the actual name of the proprietor of the feature
inasmuch as the byline says Jok Church, a question from a reader
is addressed to “Dear Jax” and the answer is signed “Jax Place”!
Be that as it may, the question posed was in essence how fast is
the sun traveling? The answer was more detailed and showed the
importance of Einstein’s conclusion that everything is relative.
For example, if you happen to be on the equator you’re spinning
around the earth’s axis at about 1,037 miles per hour. At the
same time, you’re traveling with the earth around the sun at
about 66,000 mph. Not only that, but you’re accompanying the
sun itself, and the rest of our solar system, orbiting the center of
our Milky Way galaxy at a blazing 480,000 miles and hour!
Even at nearly a half million miles an hour, it takes our sun and
us some 250 million years to make a complete orbit around the
Milky Way. So, how fast are we traveling? Take your pick –
relative to what?
These figures give some idea of the size of our galaxy, which is
in the neighborhood of half a quadrillion miles wide, give or take
a few tens of trillions of miles. The size of our galaxy sounds
pretty hefty but NASA’s Spitzer Space Telescope has turned up
something truly humongous, as alluded to in last week’s column.
A news article by Ker Than posted on AOL News on August 7
describes the discovery of a collision of three galaxies about the
size of the Milky Way and one more galaxy about three times the
size of our home galaxy. When the collision of these four
galaxies runs its course, the result could be a galaxy 10 times as
massive as our own and possibly the biggest galaxy the universe
has ever seen.
Actually, we’re seeing today the collision as it was occurring
about 5 billion years ago, so it’s possibly already finished or well
on its way to its more or less final form. In about 5 billion years
from now we should be having our own collision with a galaxy,
the Andromeda galaxy, which is headed our way. Astronomers
are working on a more precise date for the collision, which
should be an interesting affair.
It could be that the first fringes of the encounter between our
Milky Way and Andromeda will come as early as only 2 billion
years from now. In what I think was the July issue of Discover
magazine (I tore out the article but forgot to note the issue),
Jennifer Barone writes of astronomers “resizing” both our Milky
Way and Andromeda. Barone writes that until recently there
were thought to be about 10 small satellite galaxies orbiting our
Milky Way. These “dwarf” galaxies apparently are not all that
easy to spot and pin down as being satellites of our home galaxy.
Now, astronomers have found a new bunch of 8 galaxies that are
more in the “hobbit” class, very small as galaxies go.
At the same time, we may be losing what were thought to be two
of our largest satellite galaxies, the Large and Small Magellanic
clouds. Apparently, they are whizzing by us at a rate of around
200 miles a second, too fast to be satellites unless the Milky Way
weighs in at twice the accepted value. On the other hand,
astronomers have found a halo of stars around Andromeda a half
million light years from the center of that galaxy. This halo of
stars is bound to the galaxy and as a result the size of Andromeda
has increased five times its previously accepted radius. It is
likely that our own galaxy has outlier stars beyond what we’ve
thought previously. With both our Milky Way and Andromeda
getting bigger, the fringes of our two galaxies may be jostling
each other much sooner than the 5-6 billion years thought
previously.
I must say that I’m not going to lose any sleep worrying about
this future collision of our galaxies. I’ve got enough trouble
trying to figure out what to cook for dinner tonight. I bought
some strange beans at the farmer’s market on Sunday. They’re
green with bright red streaks and patches and I was told they’re
cranberry beans. I understand they’re to be shelled like lima
beans. Wish me luck.
Allen F. Bortrum
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