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Astronomy  Explorer XI  Extragalactic

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. These effects are known as extinction and interstellar reddening respectively.

Extinction Events
Frequently Asked Questions: Earth Impacts, Craters and Extinction Events ...

Extinction event
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Extinction, Scattering, and Absorption
Astronomers who specialize in photometry need to compensate for atmospheric extinction: the reduction in a celestial object's apparent brightness when its light passes through the atmosphere. This depends on three factors: ...

- Devonian Extinction. there were tetrapods on land, just not too many.
Many other nitpicks. Sorry. Could detail more if you want.
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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.

Starlight passing through a dust cloud can be affected in a couple of ways. The light can be totally blocked if the dust is thick enough or it can be partially scattered by an amount that depends on the color of the light and the thickness of the dust cloud.

The reduction in intensity of light as it passes through an absorbing or scattering medium, such as intersterllar material or a planetary atmosphere.

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
Eyepiece- a set of lenses used to magnify the image produced by a telescope's objective ...

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.

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

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. It is important to take this effect into account when measuring the apparent brightness of stars.

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.
Fabry- Perot Etalon - A nonabsorbing, multireflecting device, similar in design to the Fabry-Perot interferometer, that serves as a multilayer, narrow-bandpass filter.

(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. The normal relation is AV = 0.8 mag per kpc.

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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. This interstellar reddening must be compensated for in trying to determine the true colour and brightness of a star.

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

extinction Loss of light from the line of sight as it passes through a medium. The loss may be by scattering, in which case the light energy is taken up by the medium and promptly re-emitted at the same energy but redirected out of the line of sight.

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. Isolated small dark nebulae are called Bok globules.

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.

The K-T mass extinction obliterated the dinosaurs , pterosaurs, plesiosaurs, mosasaurs, ammonites, some families of birds and marsupial mammals, over half the plankton groups, many families of teleost (bony) fishes, bivalves, snails, sponges, sea urchins and others.

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. The more dust, the dimmer the star will appear.

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.

K-T Extinction - Text by M. Alan Kazlev
Terragen mass extinction that occurred 65 million years ago, at the boundary of the Cretaceous and Tertiary periods. Caused by an asteroid or comet impact on the Yucatan Peninsula, resulting in prolonged darkness and rapid global temperature change.

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".

exosphere Outermost fringe of Earth's atmosphere. expanding cosmological model exploding galaxy Galaxy in which powerful explosions are occurring in its central region and which is emitting nonthermal radiation. extinction extragalactic ...

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 7.6 solar, a mass of about 5 1/2 solar, and confirmation that the star is indeed a subgiant and is about to give up core hydrogen fusion.

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

Typically, the particles have size about 1 µm but there must be a wide range of particle sizes present to explain the interstellar extinction curve.

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).

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 rest escapes harmlessly into space.

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. Possible external causes include variability of the , aging of the , orbital and obliquity changes, dust-releasing vulcanism, comet impacts, a companion star to the ("Nemesis"), and galactic plane dust.

If Cruithne struck the Earth, though, that would be an extinction-level event, similar to what is believed to have occurred at the end of the Cretaceous period.

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. The most well-known of those mass extinctions is of course the dinosaur extinction some 65 million years ago.

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

Nemesis was proposed to explain some regularities of the great extinctions of life on Earth. The theory says that Nemesis creates periodical perturbations in the asteroids and comets of the solar system causing a shower of large bodies and some of them hit Earth causing destruction of life.

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.

The evidence for this star is the apparent 30 million year period of global catastrophes and consequent mass extinctions of species such as the dinosaurs, The theory suggests that Nemesis disturbs the Oort cloud, ...

The extinction of the dinosaurs is attributed to such a collision, its evidence detected by Walter Alvarez as a thin layer of iridium-rich deposit extending though Italian limestone.

Here is a recent study by some folks that link a mass-extinction that happened 450 million years to a large gamma-ray burst. Such events can severely damage the ozone layer and lead to strong disruptions to the food chain.

- Every few tens of millions of years, on average, an asteroid 10 km or so in size hits Earth. The last one caused the extinction of the dinosaurs and many other species.

According to Greek myth, he almost died after being stung by the Scorpion (Scorpius) sent by Gaia to prevent Orion from hunting all aminals to extinction. Asclepius (Ophiuchus) saved Orion's life. Mortal enemies ever since, Orion and Scorpius are never seem together in the sky.

Many people believe that the great extinction at the end of the Cretaceous period was caused by a large asteroid hitting the Earth. The resulting dust cloud then cooled the Earth and caused many species to die out, including the dinosaurs.

The impact of a near-Earth object 65 million years ago in what is today the Caribbean region, as depicted in an artist's conception. Many scientists believe that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of the dinosaurs and many other species near ...

A gamma-ray burst, for instance, may have caused the Ordovician extinction which killed 60% of all marine invertebrates 450 million years ago. No need to worry, though, as Scientists have put the chances of a gamma ray burst occurring in our galaxy at less than 1 in 10 million.

Some examples are the 1908 Siberian Tunguska impact by a comet or an asteroid and the asteroid that struck Earth 65 million years ago, which may have led to the extinction of the dinosaurs and other species of the Cretaceous-Tertiary era.

In 2267, James T. Kirk and his crew made contact with Apollo, the last of the Greek gods, who had waited for his worshipers to develop space travel and seek him out. The encounter resulted in the death of Apollo and the extinction of his species. (TOS: "Who Mourns for Adonais?") ...

The cause of these bursts is not known. Most scientists believe they come from the farthest reaches of the Universe, perhaps from the merging of two or from a explosion. If a burst ever originated nearby in our , the bath of radiation could cause mass extinction on Earth.
Catch a Bursting Star ...

Two wave trains of light from a double slit produce interference, an effect that is visible on a screen as a pattern of alternating dark and light bands caused by intensification and extinction at points at which the waves are in phase and out of phase, respectively.

It may help to visualize earthly events that were occurring when these objects released their ancient photons. For example, the Virgo Galaxy Cluster released the light we see today at an epoch of time coinciding with the extinction of the dinosaurs and the rise of the mammals and primates, ...

1940s, Turner says, and those forests have mostly disappeared because they were heavily logged during the first half of the 20th century. The wood was in high demand for fuel during World War II. "[This was] believed to be a classic case of people driving a large charismatic species to extinction by ...

nucleus of a comet with a large city would probably 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 ...

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, Orbit

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