Atmospheric Optical Phenomena Research Paper Afterglow

Atmospheric Optical Phenomena Research Paper
Afterglow
An afterglow is a broad, high arch occasionally seen in the sky. It is a white light appearing during the darker half of the twilight. It is caused by fine particles of dust suspended in the upper atmosphere.
Occurrence of an afterglow
Gamma-rays bursts, which are flashes of the gamma rays, are associated with explosions which are highly energetic. The bursts occur initially and are followed by an afterglow emitted at longer wavelengths. Models that explain the origin of gamma rays have shown that the initial burst is gradually followed by fading emissions. The emissions occur due to collisions between the interstellar gases and the burst eject.
The fading emission is called the afterglow. It is difficult to observe the position of a burst and therefore early searches for afterglows were unsuccessful. A satellite in 1997 was able to detect a gamma ray burst and a fading x-ray emission was observed, when a camera was pointed towards the origin of the burst. Once the gamma ray bursts faded, deep imaging could “identify a faint, distant host galaxy at the location of the burst as pinpointed by the optical afterglow” (Vedrenne, 2001).
There are long term effects after exposure to gamma ray bursts in the earth’s atmosphere. The gamma ray energy causes “chemical reactions involving oxygen and nitrogen which form nitrogen dioxide gas”. The gas causes a photochemical smog which covers the sky making dark. It further prevents sunlight from reaching the earth’s surface, therefore causing a cosmic winter event. Further, it depletes the ozone layer and consequently the earth becomes vulnerable to any sorts of radiation.
Airglow
An airglow is a faint photochemical glow in the higher parts of the atmosphere. It is caused by collision of x-rays and charged particles from the sun, with molecules and atoms. It occurs especially in low altitudes. The airglow hasa green oxygen line,which makes up the major subject of study to understand the appearance and occurrence of airglows.