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Extinction

Astronomy  Explorer XI  Extragalactic
04/17/2014

Extinction
Dust clouds along the line of sight scatter and absorb light coming from distant objects. We therefore see these objects as dimmer and redder than they really are.


Extinction Events
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Extinction event
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Definition: extinction: The failure of a taxonomic group to produce direct descendants, causing its worldwide disappearance from the record at a given point in time.
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atmospheric extinction
The reduction in the intensity of light from a celestial body due to absorption and scattering by Earth's atmosphere.

As for the other extinction events, while an asteroid impact almost certainly caused the demise of the dinosaurs, environmental factors such as climate variation, sea level change or intense geologic activity could have been the trigger instead.

Late Triassic The Late Triassic extinction occurred about 200 million years ago, and it killed about 50 percent of all marine species. It was belived to be caused by volcanism and global warming.

However, in the case of the Cretaceous-Tertiary (KT) extinction that killed the dinosaurs 65 million years ago, there is ample evidence of both an asteroid strike and catastrophic volcanic upheaval (the Deccan Traps).

Extinction
Starlight passing through a dust cloud can be affected in a couple of ways.

Extinction, atmospheric. The diminishing of light from astronomical objects due to the earth's atmosphere, in which molecules (air, dust, etc.) of the atmosphere absorb, reflect, and refract light before it reaches the ground.

Extinction- the apparent reduction in the brightness of a star or planet when low over the horizon because more of its light is absorbed by the Earth's atmosphere ...

Extinction Loss of light from an object as a consequence of absorption or scattering by an intervening medium. An example is the atmospheric extinction of light from stars near the horizon.

extinction
The dimming effect of the interstellar medium on starlight passing through it.
eyepiece
An optical instrument constructed of lenses which magnifies and focuses the incoming light gathered from a telescope.

Extinction
The dimming of light by intervening material; commonly, dimming by the interstellar medium.
Eyepiece ...

Extinction and survival
Crocodilians, pterosaurs, dinosaurs, and champsosaurs survived the Triassic-Jurassic extinction event
Triassic-Jurassic extinction event ...

EXTINCTION - In astronomy, the dimming of starlight as it passes through the interstellar medium. Dust scatters some of the light, causing the total intensity of the light to diminish.

Extinction. The apparent reduction in brightness of a celestial object when it is low in the sky and much of its light is absorbed by Earth's atmosphere.

Extinction - The dimming of starlight due to absorption and scattering by interstellar dust particles.

Extinction
(a) Attenuation of starlight due to absorption and scattering by Earth's atmosphere, or by interstellar dust. The longer the path through the dust, and the denser the dust, the more the starlight is reddened.

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extinction The dimming of starlight as it passes through the interstellar medium.
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Extinction is inversely proportional to wavelength so red light is less affected than blue light. Distant stars thus appear more red than they actually are.

Extinction
The apparent dimming of star or planet when low on the horizon due to absorption by the Earth's atmosphere.
Extragalactic
A term that means outside of or beyond our own galaxy.

The extinction of the light is caused by interstellar dust grains located in the coldest, densest parts of larger molecular clouds. Clusters and large complexes of dark nebulae are associated with Giant Molecular Clouds.

MASS EXTINCTION
Mass extinction is the process in which huge numbers of species die out suddenly. The dinosaurs (and many other species) went extinct during the K-T extinction, which was probably caused by an asteroid colliding with the Earth.

ELE = Extinction Level Event as far as i know
@Gray (No.12): Yes, that's pretty much it. The light from Betelgeuse takes 600 years to reach us, so any event we can see from Earth happened 600 years ago.

3. Extinction is the _____ of starlight by interstellar _____. (Hint)
4. The density of interstellar matter can be characterized as being very _____. (Hint)
5. Interstellar gas is composed of 90 percent _____ and 9 percent _____. (Hint) ...

Atmospheric extinction is the term used for defining the absorption of starlight light by the earth's atmosphere. At an altitude of 52 degrees and higher, atmospheric extinction has a factor of zero.

interstellar extinction - (n.)
The obscuration of starlight by interstellar dust. Light is scattered off of dust grains, so that a distant star appears dimmer than it otherwise would.

Interstellar Extinction: As light from a star travels through interstellar space it encounters some amount of dust. This dust scatters some of the light, causing the total intensity of the light to diminish.

interstellar extinction
The dimming of starlight as it passes through the interstellar medium.
interstellar medium
Gas and dust in interstellar space.

extinction (Galileo Project Glossary - JPL) The failure of a taxonomic group to produce direct descendants, causing its worldwide disappearance from the record at a given point in time.

extinction The attenuation of light; that is, the reduction of illuminance of a collimated beam of light as the light passes through a medium wherein absorption and scattering occur.

extent could be measured, as distinguished from a point source. Now, one which has a large angular extent and is strongest at longer wavelengths (distinguished from a compact source). Most extended sources tend to be polarized. [H76]
Extinction ...

Because of dust extinction, one always wants to use lines at the longest possible wavelength. As Susan Kleinmann once said, "I don't care if it's plastic, as long as it's in the infrared and you can see it".

expanding cosmological model exploding galaxy Galaxy in which powerful explosions are occurring in its central region and which is emitting nonthermal radiation. extinction extragalactic ...

ALVAREZ THEORY OF EXTINCTION
This theory is that a large asteroid, meteor, or comet hit the Earth 65 million years ago, causing huge atmospheric and geologic disruptions, leading to a mass extinction which killed the dinosaurs and many other species.

The last such eruption occurred some 65 million years ago (press release, Basu et al, 1993), created India's Deccan Traps, and -- in combination with the Chicxulub meteorite impact -- contributed to the extinction of the dinosaurs.

This is an extreme example of interstellar extinction which is the dimming of star light caused by the presence of interstellar material. In the dust lanes the extinction is complete. But in other regions it is only partial.

In 1980, physicist Luis Alvarez and coworkers reported finding a very high concentration of the element iridium in the sedimentary clay layer laid down at the time of the K-T extinction.

2 magnitudes of interstellar dust extinction as well as for a lot of ultraviolet light, gives a luminosity of 1980 times that of the Sun, a radius 7.

The answer lies in extinction by the carbon and iron whiskers that the QSSC uses to convert star light into CMB photons.

Mexico's Chicxulub crater is believed to be the site of a meteorite impact so immense that the resulting environmental changes caused the extinction of the dinosaurs 65 million years ago.

Paleontologists speculated and theorized for many years about what could have caused this mass extinction, known as the K-T event (Cretaceous-Tertiary Mass Extinction event).

Sharks, Atlantic cod, and Pacific sardines are tapped as particularly imperilled with extinction. The scientists recommend drastic measures to reduce ocean fishing. Nature, Environment News, BBC ...

The situation is comparable to atmospheric extinction of starlight arriving in the opposite direction. When a light ray travels straight up through clear air from sea level, only 20 to 30 percent of it is absorbed or scattered by the atmosphere.

The Death Star Theory refers to the fact that mass extinctions are periodic, and may be caused by the Earth's passing through a cloud of comets (the Oort cloud) every 26 million years.

K-T event, which caused the extinction of dinosaurs and other contemporary creatures falls into this category. The amount of destruction depends on the properties of rock in which the crater is being excavated.

An apparent 26 My periodicity to mass extinctions on Earth could be linked to climatic changes.

Atmospheric thermal currents also vary the amount of starlight passing through it and we call this atmospheric "extinction." Random intensity fluctuations of starlight passing through the atmosphere are called "scintillation.

When examining the Earth's geological record, it appears that about once every 30 million years a mass extinction of life on Earth has occurred.

Following the Cambrian explosion, about 535 Ma, there have been five major mass extinctions.

We are discovering both the fragility and robustness of life as we investigate the history of mass extinctions on our planet (including extinctions taking place today), ...

Stars in the Milky Way at Mid-Infrared Wavelengths (free from dust extinction - NASA/IRAS Image).
Warm Dust in the Milky Way (NASA/IRAS Image)
Multiwavelength Milky Way
Request a free copy of the Multiwavelength Milky Way poster. COBE Infrared view.

This event resulted in the extinction of over 50% of the species living at the...
4 years ago
What is the price per ounce or gram of a meteorite ...

atmospheric absorption or extinction
The decrease in light caused by passage through the atmoshpere.
atmospheric escape ...

Searching, finding and tracking asteroids and comets is important, probably more than any other natural threat, they are the most likely to cause a mass-extinction event here on our humble planet.

It has been thought previously that the impact which caused this crater was responsible for the Triassic-Jurassic extinction event, but scientists have pointed out that, at approx 214 million years old, ...

destroy the city but the probability of such an event occurring is exceedingly small. Some scientists suggest, however, that collisions have taken place in the astronomical past and may even, for example, have had a climatic role in the extinction of ...

Some scientists believe that just such an impact in the area of the Yucatan Peninsula in Mexico started the chain of events which led to the extinction of the dinosaurs here on Earth.

See also: See also: Earth, Astro, Planet, Sun, Solar

Astronomy  Explorer XI  Extragalactic
04/17/2014

 
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