A sweeping prominence, a huge cloud of relatively cool dense plasma is seen suspended in the Sun's hot, thin corona. At times, promineces can erupt, escaping the Sun's atmosphere. Emission in this spectral line shows the upper chromosphere at a temperatur
The Sun is now in the quietest phase of its 11-year activity cycle, the solar minimum - in fact, it has been unusually quiet this year - with over 200 days so far with no observed sunspots.
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