AAAA Observing Reports
A Trip
Through
The Universe
by
Dr. Paul Derrick,
Waco, TX
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We will be taking a trip from Ground Earth to the Edge of the Universe. Along
the way, we will take a quick look at many of the celestial objects and
astronomical phenomena which fill the universe, and which make it such an
interesting place both to live in and to study.
Earth and the Solar System
 Meteors
streak through the Earth's atmosphere, and are relatively close to the observer,
only a few miles up. Meteors usually burn up in the air, but occasionally, one
will actually hit the surface of the Earth.
One very famous artifact that resulted in a meteor collision with Earth is Meteor
Crater in Arizona. Usually, meteors vaporize upon impact, but very large
ones will leave behind a crater marking the spot they hit. In Meteor Crater,
there is a great deal of debris buried below the crater and left from the impact
that confirms that this was indeed a meteor impact. There is also a
certain amount of debris from the impact that is scattered in the surrounding
area. Meteor Crater was created 50,000 years ago, and is fairly recent in both
the geological and astronomical time scale. Any meteor that impacts with the
ground at an angle between 45 degrees and 90 degrees will leave a circular
crater, which accounts for the shape of Meteor Crater, as well as the many
craters we see on the Moon and other planets. There are many other meteor
craters that have been found on the face of the earth, but most have been filled
in over millions of years and so are indistinct.
 Above the atmosphere we can
find satellites like the Hubble Space Telescope and
many military and communications satellites. The famous first Apollo picture of
Earth gave mankind a glimpse of the our planet from space.
The Moon is the closest celestial object to
Earth. Only one side of our satellite can be seen from Earth, due to the
orbital period and the rotation of the moon being in sync. The earthshine we can
see during the Dark of the Moon is bright enough to read a newspaper by.
The Sun is the closest start to Earth. It is
also the center of our Solar System. The Sun has cycles of surface activity that
are related to the well-known 11 year sunspot cycle. The high number of sunspots
currently visible is due to the fact that we are at the peak of the current
cycle.
 Solar
Eclipses are favorite events of amateur astronomers, who often travel
many miles to view one. A solar eclipse occurs when the Moon passes in from for
the Sun. It is an interesting fact the the angular size of the Moon as seen from
Earth is almost exactly the same at that of the Sun. The next total solar
eclipse which can be seen from Texas and most of the US will be in 2024.
 The
Solar System is the family of planets that belong to our Sun, and of
which the Earth is a part. Jupiter is the largest planet in the solar system,
and is famous for its Red Spot, a great storm that his been raging on the
surface of Jupiter since 1600, when it was first discovered with a telescope.
Jupiter is the most visible active and interesting planet to observe in the
solar system. However, it is actually nothing but a cloud or big ball of gas,
mostly hydrogen, with no surface, which would make it a very difficult place to
visit. Its satellites, on the other hand, are rocky and solid, and are each
quite varied, making them interesting destinations for a future trip. It is
interesting that the solar system is made up of four inner rocky planets, and
four outer gas planets. Pluto, the ninth and outermost planet, may not be a
planet at all, but a large asteroid.
Comets are visitors to the Solar system. The
recent famous comets Hale-Bopp and Hyakutake made a brilliant spectacle as seen
from earth. Comets are "dirty snowballs" that glow as the energy from
the sun heats up their surface materials, which are then thrown off into space
as a "tail."
Out into the Milky Way Galaxy
 As we move beyond the solar system, we begin to encounter the other
inhabitants of the galaxy in which we live, the Milky Way. In addition to other
stars and their planets, there are other types of objects which we can observe.
Spectacular Deep-Sky
objects like the Great Nebula in Orion, M42, are Emission
Nebulae made up of glowing clouds of hydrogen gas. Nebulae like M42 are
"stellar nurseries" in which new stars are born from the condensation
of dust and gas. The baby stars begin to glow from the atomic fusion that is
causes by the large gravitational forces holding the stars together. Nebula like
M42 look red in photographs, but this color is not seen by the human eye,
because the light levels are not bright enough to stimulate our color vision.
 Planetary
Nebulae like the Ring Nebula (M57) in Lyra, are the remains of a nova, or
exploding star. The central star of such a nebula is a compact neutron star
caused during the stellar explosion, and can sometimes be seen in large
telescopes. Another remnant of the death of a star is the Crab Nebula (M1) in
Taurus. This nebula was caused by a supernova explosion about 1000 years
ago.
The explosion of an exceptionally large supernova can result in a Black
Hole. A black hole is a point in space that has no dimension, but has so
much mass in it that the gravity is so strong that even light cannot escape from
it. But even a black hole was originally a super large star that collapsed at
the end of its life cycle. The bigger a star is, the faster it burns up and
dies.
 Globular
Clusters are round groups of stars that live in the form of a halo around
the center of our Milky Way Galaxy. M13, the great Globular Cluster in Hercules,
is one of the most famous globular clusters visible from the Northern Hemisphers.
A globular cluster can contain more that 100,000 stars, but even so, there is so
much space between the stars that they will never collide. The distance between
stars in a globular cluster varies from less than one light-year to more than
four light-years. Globular clusters are very old, dating from the time of the
formation of the galaxy.
Beyond Our
Milky Way Galaxy
We have already mentioned galaxies and talked about our own Milky Way Galaxy.
But what is a galaxy, really?
Galaxies are families of stars, somewhat like
the solar system is a family of planets. Thus, galaxies are big conglomerations
of dust, stars, and gas held together by a black hole at the center.
The universe is made up of millions, or billions, or even trillions of
galaxies. The total number is not known. These galaxies clump together into
groups called galaxy clusters. Our Local Groups of Galaxies is made up of the
Milky Way, M31 in Andromeda, and M33, the Pinwheel Galaxy in Triangulum. Other
famous groups of galaxies are the Virgo Cluster and the Cluster in Coma
Berenices.
 M-31,
The Great Galaxy in Andromeda is the most famous examples of a galaxy. In
shape and size, it is a much like our own Milky Way, even to the extent that it
has companion galaxies M32 and M110, similar to our own galactic companions, the
Magellanic Clouds.
M-31 is the closest large spiral galaxy to our own Milky Way galaxy, and therefore presents us with a wealth of
details. Numerous dust lanes are evident, and large telescopes can even identify individual members of its system
of globular clusters.
Galaxies actually do rotate, but on a very slow time scale compared to earth:
it takes 275 million earth years for the Milky Way to rotate once!
At the edge of the universe are Quasars. Quasars
are not yet fully understood, but they are thought to be a stage in the
development of normal galaxies. The word Quasar is made up from the words
"Quasi-Stellar Source", due to their star-like appearance in a
telescope.
 A telescope is both a Visual Machine and a Time Machine. Not only does a
telescope gather light, but it also looks back in time. The farther away an
object is, the longer it takes the light of that object to reach us. Thus, when
we look through a telescope, we are looking at the object as it was perhaps
millions of years ago, instead of what is actually looks like now. When we
observe Quasars, we are looking at the very beginning of the Universe!
The Hubble Deep Field is the farthest and
deepest we have ever looked into the universe. When the Hubble Space Telescope
took a photo of a blank area of sky for 100 hours, it revealed hundreds of
galaxies which had never been seen before. The Universe is indeed immense!
"Be Glad of life ...
Because it gives you the chance
To Love, to Work, and to Play, ...
And to look up at the stars!"
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