Companion
Decades ago, it was not known with certainty whether the companion galaxy NGC 5195 was a true companion, or another galaxy passing at a distance. The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated the reality of the interaction.
Recent simulations bear out that M51's spiral structure was caused by NGC 5195 passing through the main disk of M51 about 500 to 600 million years ago. In this model, NGC 5195 came from behind M51 through the disk towards the observer and made another disk crossing as recently as 50 to 100 million years ago until it is where we observe it to be now, slightly behind M51.
Read more about this topic: Whirlpool Galaxy
Famous quotes containing the word companion:
“We often love to think now of the life of men on beaches,—at least in midsummer, when the weather is serene; their sunny lives on the sand, amid the beach-grass and bayberries, their companion a cow, their wealth a jag of driftwood or a few beach plums, and their music the surf and the peep of the beech-bird.”
—Henry David Thoreau (1817–1862)
“I endeavor not to conceal that I believe there is a great mixture of desire in the passion which is called love—or rather, without any far-fetched strain on words, it may be called the companion of love.”
—Sarah Fielding (1710–1768)
“In today’s world parents find themselves at the mercy of a society which imposes pressures and priorities that allow neither time nor place for meaningful activities and relations between children and adults, which downgrade the role of parents and the functions of parenthood, and which prevent the parent from doing things he wants to do as a guide, friend, and companion to his children.”
—Urie Bronfenbrenner (b. 1917)