he sews last year observatory on a
moonless night deep in the Attic ama
desert of chili it should be very dark
but strange green and red colors can be
seen to shimmer in the sky
what are these mysterious clothes and
why do they seem to be getting more
frequent
this is the esocast cutting-edge science
and life behind the scenes at ESO the
European Southern Observatory main
the Sun is constantly sharing the
Earth's atmosphere with radiation at
many different wavelengths solar
ultraviolet light destroys oxygen and
nitrogen molecules during the daytime
and this triggers a chain of complex
chemical reactions as a result new
molecules like ozone are created when
night falls some of these molecules take
part in further reactions and collisions
causing them to radiate light this
process is known as chemiluminescence
the result is seen in the night sky as
an eerie glimmer an effect called
airglow to the naked eye the colors of
this airglow are invisible but sensitive
wide-angle photographs show the fine
green or reddish tinge 'as of this
phenomenon sometimes airglow appears to
be just a faint tinge of colour on the
horizon but it can also be a menagerie
of changing colorful shapes the green
layer of airglow lies about 100
kilometres above the ground here it is
seen from the International Space
Station but there is also a much fainter
reddish tint of luminescent air at
altitudes over 250 to 300 kilometres
the extent color and brightness of the
airglow vary with time and place and are
influenced by many different factors for
example the red glow tends to be
brightest at the start of the night and
around midnight and later it can be very
weak and Sarah parallel home of the VLT
happens to be located below what is
known as the South Atlantic anomaly here
the Earth's protective magnetic field
which prevents particles from reaching
the surface is reduced and more
particles from the Sun hits the
atmosphere
this can lead to brighter airglow
airglow can also appear in strange
formations called gravity waves they are
formed by alternating air pressure
layers that can grow with height as the
air things we understand what causes
airglow but why are we seeing more and
more of it in photos taken at ec sites
in chile over the past five years has
eglo become more common could it be
caused by some global change in weather
patterns
the answer is not clear the recent rapid
development of digital cameras seems to
play a role allowing fainter details to
be picked up in the night sky more often
but identical cameras have revealed
dramatically different skies just weeks
apart
since airglow is triggered by
ultraviolet radiation emitted from the
Sun changes in solar activity can have a
big impact on the brightness of the
airglow
the Sun cycles through periods of low
and high activity every 11 years and was
active in recent years this it seems is
the main reason for the recent increase
in airglow the most recent cycle of high
solar activity coinciding with more
sensitive digital photography has
provided our first detailed look at this
strange phenomenon a glue can be
beautiful and photogenic but it also
affect scientific observations certain
kinds of airglow give rise to background
patterns in near infrared images from
the vista telescope as the airglow
structures move in between exposures one
way or another it's a feature of the
celestial display over the e so sites
even in one of the darkest places on the
planet
the sky is never completely dark
I heard about the only person
it doesn't have TV coverage of the page
and it man they got the black up now and
you can start getting a TV picture
never-fail yes we are getting
baby pictures
qty all
on