The Journey of Flight.pdf - Valkyrie Cadet

Chapter Chapter 25 25 - - Our Our Solar Solar System System
System
Black holes are perplexing to scientists because everything about them must be guessed. Anything
sent to investigate could not send its messages back to Earth because the black hole would absorb the
radio transmissions.
Other Galaxies
Beyond our system of stars or
galaxy, there seems to be an endless
number of other galaxies. Each time
our scientists develop techniques of
seeing farther into space, they find
other galaxies beyond the range limit
of previous instruments.
Even the galaxy-to-galaxy relationship
is in motion. In general, all
of these individual galaxies and
groups of galaxies seem to be moving
away from each other. This movement
also seems to be moving away
from a common point. However,
when the movement began is not certain,
and the outermost extent of this
expanding universe is not yet known.
547
A Universe of Galaxies
At one time, the edge was thought to be 14 billion light-years out, but where it really is and how it all
started are two things about which scientists can only speculate and theorize.
According to astronomer Douglas Richstone, “The formation and evolution of galaxies are intimately
connected to the presence of a central massive black hole. Radiation and high-energy particles
released by the formation and growth of black holes are the dominant sources of heat and kinetic
energy for star-forming gas in protogalaxies.”
Researchers have noted that nearly all galaxies with spheroidal distributions of stars (that is, bulges
in spirals) seem to have massive black holes that appear to correlate with the mass of the central part of
the host galaxy, pointing to a connection between the massive black hole and the galaxy. Additionally,
comparisons of the history of star formation in the universe with the history of quasars reveals that
quasars developed well before most star formation in galaxies. Astronomers believe the massive black
holes now seen in the centers of galaxies are relics of these quasars, indicating that the black holes
must have been present at the height of the quasar epoch when the universe was about one billion years
old.
Astronomers theorize that as galaxies formed in the early universe, powerful gravitational attraction
pulled huge amounts of gas together at their center to create a black hole. Gas and any close stars
were sucked in and converted to gas in the process. As the gas swirled into the black hole in a huge
vortex, it became hotter and hotter and glowed more and more brightly. Just before plunging into