Yohkoh Mission



This is an X-ray image of the Sun taken with the Soft X-Ray Telescope (SXT) on the orbiting Yohkoh satellite. This is an example of the deep, red images of the Sun you might've seen. This particular image was taken on November 23, 1999.
Click on image for full size version (22K JPEG)
Image courtesy of ISAS/Yohkoh team/Lockheed Palo Alto Research Laboratory

Have you ever wondered how scientists know so much about the Sun? Have you ever seen a deep, red picture of the Sun and wanted to know where it came from? Well, your questions may be answered! For most of this decade, the Yohkoh satellite has supplied us with tons of information about our closest star.

The Yohkoh Observatory was launched on August 31, 1991, from the island of Kyushu in Japan. Ever since, the satellite has sent back numerous X-ray and gamma ray images of the Sun. It uses four special instruments, two of which use spectroscopy. The other two use X-rays. Together, they send back spectacular images in light we can't normally see.

The main goal of the project was to increase our understanding of solar flares, which are sudden bursts of energy released by the Sun. Specifically, scientists want to know why X-rays and gamma rays are released during this type of event. However, the observatory also aids in the study of coronal mass ejections and other types of solar activity.

The Yohkoh satellite is controlled from the Institute for Space and Astronautical Sciences in Japan. On December 14, 2001, Yohkoh experienced a power shutdown to the scientific instruments. This power shutdown was triggered by an annular eclipse of the Sun that occurred over parts of the Pacific Ocean that same day. Efforts are being made to recover the spacecraft. Overall, the Yohkoh spacecraft has been highly successful and has provided real-time monitoring of solar activity for the sake of space weather studies.

Solar Activity

Learn more about X-rays

Yohkoh Outreach page

Yohkoh Mission



This is an X-ray image of the Sun taken with the Soft X-Ray Telescope (SXT) on the orbiting Yohkoh satellite. This is an example of the deep, red images of the Sun you might've seen. This particular image was taken on November 23, 1999.
Click on image for full size version (22K JPEG)
Image courtesy of ISAS/Yohkoh team/Lockheed Palo Alto Research Laboratory

Have you ever seen a deep, red picture of the Sun and wanted to know where it came from? Well, your questions may be answered! For most of this decade, the Yohkoh satellite has supplied us with tons of information about our closest star, the Sun.

The Yohkoh Observatory was launched on August 31, 1991, from Japan. Ever since, the satellite has sent back many X-ray and gamma ray images of the Sun. It uses four special instruments, two of which use spectroscopy. The other two use X-rays. Together, they send back images in light we can't normally see.

The main goal of the project was to increase our understanding of solar flares, which are sudden bursts of energy released by the Sun. However, the observatory also aids in the study of coronal mass ejections and other types of solar activity.

The Yohkoh satellite is controlled from the Institute for Space and Astronautical Sciences in Japan. On December 14, 2001, Yohkoh experienced a power shutdown to the science instruments. This power shutdown was triggered by an eclipse of the Sun that occurred over parts of the Pacific Ocean that same day. Efforts are being made to recover the spacecraft. Yohkoh will be considered a great success even if the spacecraft can't be recovered. Yohkoh was especially well known for providing real-time monitoring of solar activity and new data for space weather studies.

Solar Activity

Learn more about X-rays

Yohkoh Outreach page

Yohkoh Mission



This is an X-ray image of the Sun taken with the Soft X-Ray Telescope (SXT) on the orbiting Yohkoh satellite. This is an example of the deep, red images of the Sun you might've seen. This particular image was taken on November 23, 1999.
Click on image for full size version (22K JPEG)
Image courtesy of ISAS/Yohkoh team/Lockheed Palo Alto Research Laboratory

Have you seen a deep, red picture of the Sun like the one on this page? Do you know where it came from? The Yohkoh satellite may have taken it! Yohkoh was launched from Japan in 1991. For over ten years, it has been sending back images of the Sun in X-ray and gamma ray light. X-ray and gamma ray light are regions of light we can't normally see with our eyes! That's why we need Yohkoh to do the looking and picture taking for us.

The Yohkoh satellite helps scientists study solar flares. Flares are fast bursts of light given off by the Sun. They are full of X-rays and gamma rays, and scientists want to know why. Yohkoh is also used to study coronal mass ejections and other solar activity.

Yohkoh has been experiencing problems since December 2001. The trouble was started by an eclipse of the Sun. Even if the Japanese space program can't get Yohkoh out of trouble, the mission can be counted as a great success.

Solar Activity

Learn more about X-rays

Yohkoh Outreach page


Last modified September 1, 2002 by the Windows Team

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