The time of opposition can occur as much as 8.5 days away from the closest approach. The distance at close approach varies between about 54 and about 103 million km due to the planets' elliptical orbits, which causes comparable variation in angular size.
Cosmos often simply means universe. But the word is generally used to suggest an orderly or harmonious universe, as it was originally used by Pythagoras in the 6th century B.C. Thus, a religious mystic may help put us in touch with the cosmos, and so may a physicist.
It's hard to wrap your mind around the cosmos, as it extends far beyond the Milky Way, or far-off galaxies, or even our own universe. Cosmos is originally a Greek word, meaning both order and world, because the ancient Greeks thought that the world was perfectly harmonious and impeccably put in order. We now use cosmos without the idea of perfect order. Now it means, all of creation, and particularly on the scale of the stars, the planets, the black holes, the other universes, and all the stuff we don't know about. It's also, totally separately, the name of a pretty, flowering Mexican herb.