Firing Lasers to Tame the Sky
Explanation:
Why do stars twinkle?
Our atmosphere is to blame as pockets of slightly off-temperature air,
in constant motion, distort the light paths from distant astronomical objects.
Atmospheric turbulence is a problem for astronomers because it
blurs the images
of the sources they want to study.
The telescope featured in this image, located at ESOБs
Paranal Observatory,
is equipped with four
lasers to combat
this turbulence.
The lasers are tuned to a color that excites atoms floating high in
Earth's atmosphere --
sodium left by passing meteors.
These
glowing sodium spots act as artificial stars whose twinkling is
immediately recorded and passed to a
flexible mirror
that deforms hundreds of times per second, counteracting atmospheric turbulence and
resulting in crisper images.
The de-twinkling of stars is a developing field of technology and allows,
in some cases,
Hubble-
class
images to be taken from the ground.
This technique has also led to spin-off applications in
human vision science, where it is used to obtain very sharp images of the retina.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
