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Welcome to the STEREO Learning Center
A Coronagraph is an instrument which studies the Sun's outer atmosphere, the corona. From Earth the corona is most easily seen during a total solar eclipse. It is also possible to cover the bright disk of the Sun
with a disk to create a sort of mini-eclipse and allows us to see the Sun's fainter outer atmosphere. If
we do this from space we do not have to worry about the bright blue sky which makes this harder to do
from Eath's surface.
Each STEREO spacecraft has two coronagraphs which study the Sun from
space. These two coronagraphs, which are part of STEREO's SECCHI suite
of imagers, have different fields of view, using different sized
occulting disks to allow us to see the faint corona at different
distances from the Sun's surface.
The image is from STEREO SECCHI's Cor2 coronagraph on the
Ahead spacecraft. The white circle shows the size and location of the Sun's surface.
The color isn't "real". We color code the images so we can
tell them apart quickly.
The main feature to notice in this image is a faint coronal mass ejection
(CME). CMEs are huge magnetic eruptions which blast off the Sun and can affect us here on Earth.
Some images from the coronagraphs and the
Heliospheric Imagers also show planets, stars, and even
In addition, there are various strange looking features that are artifacts of the instruments.
You can read more about those on
Last Revised: Friday, 03-Jun-2022 11:56:41 EDT
Responsible NASA Official:
Webmaster: Kevin Addison