How big is Marathon? | Scale of the Universe

A marathon is a running race over a set distance of 42.195 kilometers (26 miles 385 yards, or about 26.2 miles). World Athletics, the sport's international governing body, fixes that distance in its rules. It is measured along the shortest path a runner could take on the course.

Distance

The marathon distance is exact. The World Athletics rules list the marathon among the standard road race distances at 42.195 kilometers, and World Athletics' history of the event gives the same distance as 26 miles 385 yards. The two agree to about a centimeter: 26 miles 385 yards is 42,194.988 meters.

A marathon has no fixed start or finish. Each race lays out its own course on roads, which can be a loop, an out-and-back route or several laps. Some major championship marathons finish inside a stadium. Whatever the route, the course must not be shorter than 42.195 kilometers.

Size comparisons

A marathon is about 105 and a half laps of a standard 400-meter running track.
It is about 4.8 times the height of Mount Everest, 8,849 meters (29,032 feet).
It is about 1.7 times the width of a neutron star, about 24–26 kilometers across, which is the collapsed core of a massive star.
Nix, a small moon of Pluto, is about 48 kilometers (30 miles) long, a little longer than a marathon.
About 950 marathons laid end to end would reach around Earth at the equator, a distance of 40,075 kilometers (24,901 miles).

Why 42.195 kilometers

The race is named after a legend. A Greek soldier called Philippides, or Pheidippides, is said to have run 26 miles (42 kilometers) from the battlefield of Marathon to Athens. He announced that the invading Persians had been defeated, then died of exhaustion.

The first modern Olympic Games, held in Athens in 1896, included a marathon of about 40 kilometers (25 miles). At the 1908 Olympic Games in London, the distance was set at 26 miles. According to World Athletics, 385 yards were then added. The start was moved farther back so that the children in the royal nursery at Windsor could see it, while the finish stayed in front of Queen Alexandra at the White City Stadium.

The distance of 26 miles 385 yards became the standard in 1921. Women first ran the marathon at the Olympic Games in 1984, in Los Angeles.

How a course is measured

World Athletics and AIMS, the association of marathons and distance races, approve only one way to measure a road course: the calibrated bicycle method. A measurer rides the course on a bicycle with a counter on its front wheel, which records how many times the wheel turns. Comparing that count with the count for a calibration course of known length gives the length of the race course.

At competitions that count toward the world rankings, the measurement must be accurate to within 0.1%, or 42 meters, and done in advance by an international course measurer. To make sure a course is never found to be short, measurers are advised to add 0.1%, laying out 1,001 meters for every kilometer. A course laid out this way is about 42 meters (46 yards) longer than the official distance.

A course must be measured again after five years, even if nothing about it has changed. For a time to count as a world record, the course must not drop more than 1 meter for every kilometer from start to finish. The start and finish must also be no farther apart, in a straight line, than half the race distance. These rules keep a course from being too steeply downhill or from giving runners a long tailwind.