The Hinode spacecraft was in the right place at the right time to catch the solar eclipse. What’s more, because of its vantage point Hinode witnessed a “ring of fire” annular eclipse.
An annular eclipse occurs when the Moon passes directly in front of the Sun but doesn’t cover it completely because the Moon appears too small. (The apparent size of the Moon depends on its distance from Earth or, in this case, the spacecraft.) About one-third of all solar eclipses are annular.
“This is only the second annular eclipse Hinode has witnessed since it launched in 2006,” said Patrick McCauley of the Harvard-Smithsonian Center for Astrophysics.
The Hinode’s X-ray Telescope (XRT) was developed and built by the Smithsonian Astrophysical Observatory and the Japan Aerospace Exploration Agency. The XRT is the highest-resolution solar X-ray telescope ever flown.
The XRT collects X-rays emitted from the Sun’s corona — the hot, tenuous outer layer that extends from the Sun’s visible surface into the inner solar system. Gas in the solar corona reaches temperatures of millions of degrees. The energy source that heats the corona is a puzzle. The Sun’s surface is only 10,000° Fahrenheit (5,500° Celsius), while the corona is more than 100 times hotter.
“We are very interested in studying solar flares,” said McCauley. “Flares are most dramatic in X-rays, and we’re using the XRT to better understand the physical mechanisms that drive flares so that they might someday be forecasted.”