You've never been closer to the planet Mars. Nobody has. Not for more than fifty thousand years, not since the only people on Earth were Neanderthal. The red and blue planets line up with the Sun this morning at 10:51am BST, and it's the closest they've been to one other for exactly 59,619 years. Since 12th September 57,617 BC in fact. That may sound like an unbelievably accurate figure, but it's typical of an exact science like astronomy where computers can warn us to watch out for a doomsday asteroid on Saturday 16th March 2880 and probably predict Jesus's birthday as an encore.
Today Mars is only 34,646,418 miles away from the Earth. Or, to put it another way, a mere 186 light seconds distant. The two planets actually pass fairly close quite often. Both race round the Sun on separate orbits, with the inner Earth catching up with Mars roughly every 26 months. This time, however, the celestial overtaking manoeuvre happens when Mars is almost at its very closest to the Sun (that's tomorrow), so the two planets are especially close together. It's called perihelial opposition. We're also only a few weeks past the Earth's furthest point from the Sun, and this and other wobbles over time in the two orbits make today's approach record-breakingly close. It's all explained here and here if you need the finer details, and here's a map showing the planets in their orbits.
A few facts about Mars. It's the seventh largest planet in the solar system (it's quite small), it's the fourth in line from the Sun, the Romans named it after the god of war, it weighs one tenth as much as the Earth but has roughly the same area of dry land, it has only two known moons, it has a highly elliptical orbit (another reason for today's close approach), it spins on its axis once every 24 hours 37 minutes (about the same as us), it's not full of little green men, it's home to the largest mountain in the solar system, and Gustav Holst wrote a stirring piece of music about it. The first probe to reach Mars flew past in 1964, the Viking lander touched down here in 1976, the ill-fated Mars Explorer of 1992 disappeared without trace wasting $980 million, and British probe Beagle 2 is on its way at the moment, due to arrive on Christmas Day.
Mars should now be visible in the southern sky around midnight, glowing red and brighter than any star. That's so long as there aren't any clouds even nearer to Mars than you are. At magnitude -2.9 this is your best chance to see the red planet for many years. But don't worry if you miss it because Mars will be even closer on Monday 29th August 2287, which is still well before that asteroid hits.