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Yohkoh — Predecessor of Hinode

About a year ago, on September 23, 2006, the Hinode satellite was launched, which keeps sending us excellent solar data. Here we would like to remind you another excellent solar data archives at DARTS; that is about Yohkoh (meaning sun-light in Japanese), the predecessor of Hinode.

Yohkoh, the second Japanese solar satellite following Hinotori, was launched on August 30, 1991. Yohkoh carried out precise solar observations primarily in X-rays till December 2001. The picture shown right is one of the early X-ray pictures, taken on September 15, 1991.

All the Yohkoh data taken during its 10 year life-time are publicly released from DARTS/Yohkoh archives, whose design and user-interface are recently improved. Besides scientific data for expert solar scientists, there are tons of beautiful images and movies of the sun. Please visit us and take a look! We show some interesting examples in the following. It is well-known that sun is spinning at 27 day period, and repeating the active cycle in 11 years. By comparing the data taken during long periods of time, you may clearly see how the solar activities vary in time.

• Solar calendar: October 1991 (active sun), March 1996 (quiet sun), August 1999 (slightly active sun)
• A huge flare on February 21, 1992 (movie)
• Yearly movie: 1992 (active sun), 1996 (quiet sun)

September 2007