NOAA SATELLITE OBSERVES VENUS TRANSIT
June 8, 2004 — The NOAA Space Environment Center in Boulder, Colo., used the NOAA GOES-12 satellite space weather instrumentation today to observe the passage of Venus in front of the sun. This transit of Venus is the first in 122 years. The GOES observation, using its Solar X-ray Imager, is unique because it records the sun’s 2 million degree, outer atmosphere in X-rays. This observation is possible only from space, since Earth’s atmosphere blocks out X-rays. The GOES-12 SXI is the only spacecraft to observe this event from space in X-rays. [Animation of Venus Transit from 12:54 a.m. to 8:44 a.m. EDT] (Click NOAA composite image for larger view of Venus transit as captured by the NOAA Solar X-ray Imager from 12:54 a.m. to 8:44 a.m. EDT. Click here for high resolution version, which is a large file. Please credit “NOAA.”)
In the NOAA
images, Venus appears as a dark disk about 1/30th the sun’s apparent
diameter. Since the sun’s atmosphere or corona extends well above
the disk seen in visible light, Venus was visible in silhouette for approximately
nine hours, versus the six hours seen from Earth. The path across the
disk is from the southeast to the southwest.
The GOES-12 SXI takes a full-disk image of the sun’s atmosphere once every minute. The images are used by NOAA and the U.S. Air Force to monitor and forecast solar flares, coronal mass ejections, coronal holes and active regions. These features are the dominant sources of disturbances in space weather that lead to geomagnetic storms.
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