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What
Is…?
?
What is a Meteor?
?
What is a Star?
What is an Open Cluster?
What is a Nebula?
What is a Comet?
?
What is a Quasar?
What is a Black Hole?
?
What
Is
Astronomy?
Reflection nebula IC4606
by George Greaney
What is Astronomy?
Astronomy is a science that attempts
to understand the make-up and the
Galaxy M83 in Hydra
history of the universe.
by George Greaney
Basically, if its off this planet its a
study of some realm of astronomy.
As one might imagine that covers an
awful lot of subjects, even more than
we know right now. A short list of
subjects include:
•NGC 253, galaxy in Sculptor
by George Greaney
•Stars
•Nebula
•Planets
•The Sun
•The Great Andromeda Galaxy
by George Greaney
•Star clusters
•Galaxies
•Galaxy clusters
•Dark matter
•Black holes
An Astronomer is a
Scientist, skilled in
Mathematics,
Physics, and
Astronomy
Most Professional
Astronomers work
for Universities or
Government
Agencies
Galileo Observatory in Italy
Source: The Berkeley Cosmology Group
What
is an
Galileo Galilei (1564-1642)
Astronomer?
A night watchman with a college education?
Few astronomers spend
much time looking through a
telescope. Most operate
telescopes from a control
room or even from their
computer at home via the
Internet.
Typical astronomers only
spend one or two weeks each
year observing, and the rest
of their research time
analyzing their data.
Source: Applied Theoretical and Computational Physics Division
Los Alamos National Laboratory
Astronomer Serena Kim at work
At Cerro Tololo in Chili
What is
an
Amateur
Astronomer?
Amateurs and their tools
What is an Amateur
Astronomer?
Although the Term has
different meanings for
different people, a basic
definition would include
anyone who looks into
the sky, and wants to
see or learn more.
Tonight
You
are an
Amateur
Astronomer
What
Is a
Meteor?
A Meteor from
the annual
Leonid Meteor
shower lights
the sky
A Meteor is a bright streak across the sky,
or a “Shooting star” produced when a
small piece of comet or asteroid,
called a meteoroid, enters the Earth’s
atmosphere.
Source:
The Lowell Observatory
What is a
Meteoroid?
The Giant Asteroid Gaspra
A meteoroid is the dust, rock,
or debris still in space. It could
be a chunk of an asteroid or
comet.
Source:
NASA
What
is a
Meteorite?
The Giant Asteroid Gaspra
Meteorite Damage, Peekskill, NY
A meteorite is a meteor that
actually falls to the ground. Most
meteors burn up and never make it
to the ground.
Source:
NASA
What
Is a
Comet?
Comet Ikeya Zhang
Image by Dave Dockery
Astronomical Society of Las Cruces
A comet is basically a ball of ice and dust
in space. The typical comet is less than
10 kilometers across. Most of their time
is spent frozen solid in the outer reaches
of our solar system.
Comet Hale Bopp
Image by Harvard-Smithsonian Center for Astrophysics
A comet orbits around the sun, in a
wide, elliptical path. When a comet
gets within a few million miles of the
sun, it begins to melt, leaving a tail of
gas and dust that is blown by solar
winds
Comet Hale Bopp
Source:
NASA
Image by Harvard-Smithsonian Center for Astrophysics
What
Is a
Star?
Image of the Sun from Goddard Space Flight Center
What is a Star?
Our Sun is the closest star.
At the simplest, a star is just a ball of gas
that has condensed out of interstellar material.
The largest part of its lifetime is spent as a
main sequence star during which hydrogen
is being converted to helium balancing
gravitational contraction so that the radius
and energy output remain almost constant.
Source: The British Astronomical Association
Our Sun is a star that has already spent
about 5 billion years on the main sequence.
Scientist believe our Sun is roughly halfway
through it's life.
Source: The British Astronomical Association
Nearby Stars:
Name
Distance from Earth
Sun
93 million miles (8 light minutes)
Proxima Centauri
4.22 Light Years
Alpha Centuri A,B
4.39 Light Years
Barnards Star
5.94 Light Years
Wolf 359
7.8 Light Years
Lalande 21185
8.3 Light Years
Sirius A,B
8.6 Light Years
Image courtesy of Dave Dockery
Astronomical Society of Las Cruces
Source: The British Astronomical Association
What is a
Light
Year?
Buzz Lightyear - Superhero
A Light Year is a unit of Distance,
not time. It is the distance that
light travels in one earth year,
which works out to:
5,903,300,000,000 Miles
A Light Year is almost
six trillion miles long!
That’s a long way! But even further
Than most folks realize.
Compare this to a
distant but familiar
object, Like Pluto.
Pluto, as seen by the
Hubble Space Telescope
Pluto is about
5 light HOURS from Earth.
Only a small fraction of a light year
What is a
Star Cluster?
Omega Centauri
Image by Dave Dockery
Astronomical Society of Las Cruces
Star Clusters are collections of a few
dozen to many thousands of stars,
which are gravitationally bound.
The Pleiades,
an open cluster
Image by Dave Dockery
Hercules Cluster,
a globular cluster
Image by Dirk Langenbach
What
Is a
Nebula?
North American Nebula,
Image by George Greaney
A nebula is a cloud of gas
and dust in space. Some
nebulas are regions where
new stars are being formed,
others are the remains
of dead or dying stars.
Reflection Nebula IC4592/4601 in Scorpius
, byGeorge Greaney
Source:
NASA
Types of Nebula:
Emission Nebula
An Emission Nebula absorbs the light of
nearby stars and reaches very high
temperatures. Emission nebula are
often found in regions of space where
new stars are forming.
The Orion Nebula
Source:NASA
Image by Dave Dockery
Astronomical Society of Las Cruces
Types of Nebula:
Reflection
Nebula
A Reflection Nebula
is a cloud of gas and
dust which does not
create its own light,
but instead shines
by reflecting the light
from nearby stars.
Source:NASA
The Pleiades
Image by Dave Dockery
Astronomical Society of Las Cruces
Types of Nebula:
Planetary
Nebula
A planetary nebula is
created when a star
blows off its outer
layers into space,
forming a nebula
In the shape of a
ring or bubble
Source:NASA
The Dumbell Nebula
Image by George Greaney
Types of Nebula:
Absorption Nebula
Dark clouds in space are called
absorption nebulas or dark nebulas.
An absorption nebula is a cloud of gas
and dust which blocks light from the
regions of space behind it. The Horsehead Nebula
Image by George Greaney
The term Nebula was first coined in the
19th century by Herschell, a famous
astronomer, to distinguish anything in
the sky that looked indistinct. Some of his
'nebulae' turned out to be entire galaxies
such as the Andromeda “Nebula“.
The Andromeda Galaxy
Image by Dave Dockery
Astronomical Society of Las Cruces
What is a
Black Hole?
Illustration of Cygnus X-1 from the Astronomy Cafe
What is a Black Hole?
Loosely speaking,
a black hole is a
region of space that has
so much mass concentrated
in it that there is no way for a
nearby object to escape its
gravitational pull.
Source: The Berkeley Cosmology Group
What
is a
Quasar?
Images from Hubble Space Telescope
What is a Quasar?
Quasars are one of the
Most mysterious and rare
objects in astronomy
A quasar is a very, Very
bright object at the core
of a few highly active
galaxies. Quasars are
thought to form as matter
spins into super massive
black hole at the center
of these galaxies.
Illustration from the Astronomy Cafe