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On 20 April, 1535, Sweden's capital city Stockholm experienced a natural spectacle so unique it was believed to be a warning directly from God. For two hours the morning skies over the city were filled with brilliant white circles and arcs. The sun was surrounded by a number of iridescent, almost ghostly companion suns.

Residents of the city believed God was indicating his displeasure with the actions of the country's ruler King Gustav Vasa. Not only had the king recently introduced the protestant faith to Sweden, but he was renowned for his intolerance of those allied with King of Denmark - Gustav Vasa had led a successful rebellion against Denmark before he became king.

The atmospheric phenomenon responsible for causing such thinking is known as a sundog. Similar in shape to the natural sun, a sundog can also look like a comet, and always appears beside the sun. It's not unusual to see two sundogs, one on each side of the sun. The scientific name for them is parhelia, from the Greek words "para" (meaning "next to"} and "helios" (meaning "sun"). Greek philosopher Aristotle called them "mock suns".

Sundogs are usually seen at sunrise and sunset, when the sun is close to the horizon. They are created when sunlight reflects off or refracts through the tiny ice crystals in cirrus or cirrostratus clouds the clouds that look like white bands or patches of fleece. Each piece of cloud ice is hexagonally shaped and no bigger than the smallest grain of sand. When sunlight refracts or passes through horizontally-shaped ice crystals it bends the light the same way a prism does, producing a spectrum of colours which fan out to create a crisp, bright sundog. The part of the sundog closest to the sun is red, gradually fading to pale blue on the side furthest from the sun. Sunlight reflecting off an ice crystal will produce a white sundog.

When the light refracts through an elongated ice crystal an arc or a halo appears in the sky. Obviously many different shapes made up the ice crystals in the clouds that day in Stockholm. When one considers how differently the light reacts in each crystal shape it's not surprising people viewed the ethereal images in the sky as an omen. In an attempt to put a stop to the rumours about the divine warning to the king, a painting was commissioned to commemorate the occasion.

When King Gustav saw the painting he believed it to be a conspiracy, seeing himself as the real sun surrounded by treacherous "mock suns". All those involved in the commission

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