The last time humans looked up and saw such a dazzling vision of the Red Planet they were living in caves and wearing animal skins.
The precise time of closest approach will be 9.51am (Irish time) tomorrow, when a mere 34,646,418 miles will separate the Earth and Mars 145 times the distance to the Moon.
As it is daytime, the moment will be missed in Ireland. But during the night before or after, Mars will only be about 2,000 miles further away and just as great a spectacle.
Already it is impossible to miss the planet, a fiery yellow-orange disc in the south-eastern sky that far outshines the brightest star, Sirius.
The event is a big occasion for amateur astronomers, who will have to wait 284 years for Mars to come as near again.
In Britain, National Astronomy Week has been timed to coincide with the Martian close encounter.
Robin Scagell, vice-president of the Society for Popular Astronomy, said a telescope with an aperture of four inches or more would reveal surface details on Mars.
"You will certainly see the south polar cap, which is really glistening at the moment," he said. "You can also see all the dark markings that are visible on the Hubble space telescope photos obviously not in such detail, but not far off."