Cosmology Exhibit ? Museum of Natural History
As you walk through the doors of the Cosmology Exhibit, the visitor is surrounded by a vast sensation of open space. The roof is a high dome, and everything is a velvet black. Seating for the Cosmology Exhibit is in the center of the large space, and small rows of white lights lead along the paths to the center of the room.
The seats are comfortable, plush affairs that are reclining, and will move as the story unfolds. The exhibit plays for approximately one hour, and repeats for 30 days before the exhibit is changed, and new items are substituted into the program.
Given the billions of stars in the night skies, this display will be ever changing as it takes the visitor off to places of unimaginable beauty and violence. The birth of stars, the growth of galaxies, and the ultimate death of a star all play out in compressed time for those fascinated with ?What?s Out There?.
What is the Universe? Simply stated, it is everything with which we are physically connected. Even that vast emptiness called ?space?. It is believed by many that our universe began in an incredibly energetic explosion called The Big Bang somewhere between 10 and 20 billion years ago. In the first milliseconds after the explosion, everything was energy, but matter formed from that energy.
Most of the universe is composed of hydrogen, and most of the remainder is helium. In essence, everything we know is essentially cosmic debris. And although all of this happened billions of years ago, the after effects are still seen today. We believe one of the ongoing effects of the Big Bang is that the universe is expanding, and because of the finite speed of light, what we see today actually is a look back in time, sometimes billions of years in the distant past.
The universe is thought to be rather clumpy. Stars, dust, galaxies, nebula all seem to cluster together and are not homogenously distributed in the universe as we see it.
What are galaxies? They are aggregates of gas, dust, and millions of stars held together by mutual gravitational forces. There are three categories of common galaxies, and several less common ones. These are all based on shape of the galaxy.
Elliptical or Type E galaxies range from E0, which is almost spherical to E7 or highly elongated. Elliptical galaxies contain little or no gas and dust. They are thought to consist almost entirely of old stars. They are more numerous than spiral galaxies, but less conspicuous due to their smaller size.
Spiral galaxies, known as S galaxies are those with a central structure from which extend curving arms. Barred spirals or type SB galaxies have an apparent bar of stars and interstellar matter running through their nuclei plane. They are designated S0 and are nearly spherical and featureless. Sa, Sb and Sc are with spiral arms that are increasingly spread out and the nuclei that are progressively fainter. Spiral galaxies contain a lot of gas and dust as well as old and young stars.
Irregular galaxies are Type I galaxies and lack a defined shape.
Radio galaxies are those galaxies that emit enormous amounts of radio energy. All galaxies emit some radio energy, but some such as Cygnus A (M87) are strong emitters.
Quasars are quasi-stellar radio sources are extremely bright, extremely distant, high energy objects thought to be the energetic cores of young galaxies. The most likely source of a quasar?s power is one or more supermassive black holes. These are regions so dense that not even light can escape their gravitational field. Black holes pull in stars, gas, and dust surrounding the galaxies center, and as these are compressed and heated, they emit the radiation we perceive as a quasar.
Stars are composed of mainly hydrogen gas. Their light comes from the energy produced at their cores by nuclear fusion This energy emerges from the surface of a star as the light we see as well as ultraviolet light, X rays and radio wasve.
Stars range in size from perhaps as much as 100 times the mass of the Sun to only one-tenth its mass. The stars that are many times more massive than the Sun are larger, hotter, brighter, and live much shorter lives, less massive stars are smaller, cooler, dimmer and live much longer. Our Sun is about average in most of its physical properties. It?s mass is about 1.989 x 1010 kg. It has a diameter of 1,392,000 km average. It?s power output is about 3.85 x 1016 watts.
Stellar evolution seems to follow this sequence: Interstellar cloud ->contracts and heats up so that nuclear fusion occurs ->becomes a main sequence star -> surface cools and becomes a red giant -> low mass stars become white dwarfs, very massive stars become supergiants -> supernova -> supernova may become a black hole or a neutron star (pulsar).
Astronomers look at two major properties when studying a star: it?s bright ness and its surface temperature. The bright ness of a star is often referred to as its magnitute, and is given a numberical value. The higher number signifies a dimmer tar. Apparent magnitude is the brightness of a star or other object as seen from Earth. It is denoted by the small letter m.
The absolute brightness of a star is denoted by the capital letter M and is defined as the magnitude of the star if it were exactly 10 parsecs (32.6 light years) from Earth.
A star?s temperature cannot be measured directly, but can be deduced from the star?s color, or spectrum of the light it emits. Red stars are coolest with surface temperatures barely a couple of thousand degrees Kelvin. Yellow stars are mdium hot, about 5,500 Kelvin and white stars are tens of thousands of degrees K. The very hottest blue white stars are more than 50,000 degrees K.
There is also a classification system called ?spectral type? that groups stars by the strengths and positions of absorption lines in their spectra.
Luminosity:
Supergiants Ia, Iab, Ib
Bright giant II
Giant III
Subgiant IV
Main sequence V
White dwarf Vi, VII
Spectral types:
Type Color Temperature Example
O Blue 25,000-50,000 δ Orionis
B Blue 11,000-25,000 Rigel (β Orionis)
A Blue-White 11,000-75,000 Sirius (α Canis majoris)
F White 6,000-7500 Procyon (α Canis minoris)
G Yellow-White 5000-6000 The Sun
K Orange 3500-5000 Arturus (α Bootis)
M Red 3000-3500 Antares (α Scorpii)
Tonight?s show will take visitors off first to visit the unusual structure called the Double Helix Nebula. It lies about 300 light years from a large black hole designated Sagittarius A at the center of our Milky Way galaxy. When viewed in the infra-red, this unusual reddish-orange cloud appears as a double Helix strand of DNA, and has been called ?Cosmic DNA?. Seen through the image are several very large giant stars.
http://i272.photobucket.com/albums/jj171/Azjahh/Museums/6903a-prvDoubleHelix.jpg
(Photo: NASA/JPL Caltech/ M. Morris (UCLA))
As you walk through the doors of the Cosmology Exhibit, the visitor is surrounded by a vast sensation of open space. The roof is a high dome, and everything is a velvet black. Seating for the Cosmology Exhibit is in the center of the large space, and small rows of white lights lead along the paths to the center of the room.
The seats are comfortable, plush affairs that are reclining, and will move as the story unfolds. The exhibit plays for approximately one hour, and repeats for 30 days before the exhibit is changed, and new items are substituted into the program.
Given the billions of stars in the night skies, this display will be ever changing as it takes the visitor off to places of unimaginable beauty and violence. The birth of stars, the growth of galaxies, and the ultimate death of a star all play out in compressed time for those fascinated with ?What?s Out There?.
What is the Universe? Simply stated, it is everything with which we are physically connected. Even that vast emptiness called ?space?. It is believed by many that our universe began in an incredibly energetic explosion called The Big Bang somewhere between 10 and 20 billion years ago. In the first milliseconds after the explosion, everything was energy, but matter formed from that energy.
Most of the universe is composed of hydrogen, and most of the remainder is helium. In essence, everything we know is essentially cosmic debris. And although all of this happened billions of years ago, the after effects are still seen today. We believe one of the ongoing effects of the Big Bang is that the universe is expanding, and because of the finite speed of light, what we see today actually is a look back in time, sometimes billions of years in the distant past.
The universe is thought to be rather clumpy. Stars, dust, galaxies, nebula all seem to cluster together and are not homogenously distributed in the universe as we see it.
What are galaxies? They are aggregates of gas, dust, and millions of stars held together by mutual gravitational forces. There are three categories of common galaxies, and several less common ones. These are all based on shape of the galaxy.
Elliptical or Type E galaxies range from E0, which is almost spherical to E7 or highly elongated. Elliptical galaxies contain little or no gas and dust. They are thought to consist almost entirely of old stars. They are more numerous than spiral galaxies, but less conspicuous due to their smaller size.
Spiral galaxies, known as S galaxies are those with a central structure from which extend curving arms. Barred spirals or type SB galaxies have an apparent bar of stars and interstellar matter running through their nuclei plane. They are designated S0 and are nearly spherical and featureless. Sa, Sb and Sc are with spiral arms that are increasingly spread out and the nuclei that are progressively fainter. Spiral galaxies contain a lot of gas and dust as well as old and young stars.
Irregular galaxies are Type I galaxies and lack a defined shape.
Radio galaxies are those galaxies that emit enormous amounts of radio energy. All galaxies emit some radio energy, but some such as Cygnus A (M87) are strong emitters.
Quasars are quasi-stellar radio sources are extremely bright, extremely distant, high energy objects thought to be the energetic cores of young galaxies. The most likely source of a quasar?s power is one or more supermassive black holes. These are regions so dense that not even light can escape their gravitational field. Black holes pull in stars, gas, and dust surrounding the galaxies center, and as these are compressed and heated, they emit the radiation we perceive as a quasar.
Stars are composed of mainly hydrogen gas. Their light comes from the energy produced at their cores by nuclear fusion This energy emerges from the surface of a star as the light we see as well as ultraviolet light, X rays and radio wasve.
Stars range in size from perhaps as much as 100 times the mass of the Sun to only one-tenth its mass. The stars that are many times more massive than the Sun are larger, hotter, brighter, and live much shorter lives, less massive stars are smaller, cooler, dimmer and live much longer. Our Sun is about average in most of its physical properties. It?s mass is about 1.989 x 1010 kg. It has a diameter of 1,392,000 km average. It?s power output is about 3.85 x 1016 watts.
Stellar evolution seems to follow this sequence: Interstellar cloud ->contracts and heats up so that nuclear fusion occurs ->becomes a main sequence star -> surface cools and becomes a red giant -> low mass stars become white dwarfs, very massive stars become supergiants -> supernova -> supernova may become a black hole or a neutron star (pulsar).
Astronomers look at two major properties when studying a star: it?s bright ness and its surface temperature. The bright ness of a star is often referred to as its magnitute, and is given a numberical value. The higher number signifies a dimmer tar. Apparent magnitude is the brightness of a star or other object as seen from Earth. It is denoted by the small letter m.
The absolute brightness of a star is denoted by the capital letter M and is defined as the magnitude of the star if it were exactly 10 parsecs (32.6 light years) from Earth.
A star?s temperature cannot be measured directly, but can be deduced from the star?s color, or spectrum of the light it emits. Red stars are coolest with surface temperatures barely a couple of thousand degrees Kelvin. Yellow stars are mdium hot, about 5,500 Kelvin and white stars are tens of thousands of degrees K. The very hottest blue white stars are more than 50,000 degrees K.
There is also a classification system called ?spectral type? that groups stars by the strengths and positions of absorption lines in their spectra.
Luminosity:
Supergiants Ia, Iab, Ib
Bright giant II
Giant III
Subgiant IV
Main sequence V
White dwarf Vi, VII
Spectral types:
Type Color Temperature Example
O Blue 25,000-50,000 δ Orionis
B Blue 11,000-25,000 Rigel (β Orionis)
A Blue-White 11,000-75,000 Sirius (α Canis majoris)
F White 6,000-7500 Procyon (α Canis minoris)
G Yellow-White 5000-6000 The Sun
K Orange 3500-5000 Arturus (α Bootis)
M Red 3000-3500 Antares (α Scorpii)
Tonight?s show will take visitors off first to visit the unusual structure called the Double Helix Nebula. It lies about 300 light years from a large black hole designated Sagittarius A at the center of our Milky Way galaxy. When viewed in the infra-red, this unusual reddish-orange cloud appears as a double Helix strand of DNA, and has been called ?Cosmic DNA?. Seen through the image are several very large giant stars.
http://i272.photobucket.com/albums/jj171/Azjahh/Museums/6903a-prvDoubleHelix.jpg
(Photo: NASA/JPL Caltech/ M. Morris (UCLA))