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:
“This film is apparently meaningless, but if it has any meaning it is doubtless objectionable.”
—British Board Of Film Censors. Quoted in Halliwell’s Filmgoer’s Companion (1984)
“The Indian remarked as before, “Must have hard wood to cook moose-meat,” as if that were a maxim, and proceeded to get it. My companion cooked some in California fashion, winding a long string of the meat round a stick and slowly turning it in his hand before the fire. It was very good. But the Indian, not approving of the mode, or because he was not allowed to cook it his own way, would not taste it.”
—Henry David Thoreau (1817–1862)
“Terrified of being alone, yet afraid of intimacy, we experience widespread feelings of emptiness, of disconnection, of the unreality of self. And here the computer, a companion without emotional demands, offers a compromise. You can be a loner, but never alone. You can interact, but need never feel vulnerable to another person.”
—Sherry Turkle (b. 1948)