Very Short Fact: On this day in 2003, Mars makes its closest approach to Earth in nearly 60,000 years, passing 34,646,418 miles (55,758,005 km) distant.
The planets and their mutual gravitational pulls are continuously changing configuration. Chaos theory says it is therefore impossible to predict planetary positions more than a few million years ahead. However, it can be shown that the Solar System is sufficiently stable that no planet is likely to collide or be ejected in the next few billion years. We are probably safe for at least 5 billion years, which is when astronomers expect the Sun to swell up into a red giant, whereupon the wanderings of Mars will be the least of the problems faced by any far future Earthlings.
[p. 23, 24, Planets: A Very Short Introduction, by David A. Rothery]
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NASA Mars landing gif via giphy.com