The Gods also took from Midgard two children known as Bil and Hjuki, as they were walking away from the spring known as Bygir, and made them accompany the children of Mundilifari as they encircle the Earth, as may be seen from Midgard at night. The father of Bil and Hjuki was a man named Vidfinn, and he is greatly honored that his children were chosen to ride among the Gods.
Sol goes around the Earth at great speed because she is pursued by a great wolf called Skoll who runs across the sky to catch and kill her. Her great fear of being caught is what drives her to race hard. There is another wolf who runs in front of Sol called Hati Hrodvitnisson, and he is in pursuit of her brother Mani, and he wishes to kill him as well.
There is a wonderfully poetic stanza from Voluspa about Sol and Mani :
" The Sun climbed, the Moon' s companion,
raised it's right hand over heaven' s rim.
The Sun did not know where it's hall would stand ,
The stars did not know where they would be set,
The Moon did not know what would be it's might,
Then all the Gods met to give judgement,
The Holy Gods took counsel together,
They named night, and night' s children,
Gave names to morning and noon,
Afternoon and evening, as well,
Gave order to time by years. "
Next : So where did the big bad wolves come from ?
Go with Odin' s wisdom, Freyja' s love, and Thor's protection !