The astronauts aboard NASA’s Artemis II mission just set a new record in human spaceflight: the furthest anyone has been from the surface of the Earth in the history of our species.
It’s hard to understand the scales involved, so here’s a diagram to try to make sense of it:
Their lunar flyby reached 406,771 km above sea level at its peak at 00:07 UTC on April 7th, which puts them in an incredible group of just 28 people to have ever been more than 1,000 miles above our home planet.
Space is so huge, and so empty, that diagrams showing the Solar System, or the Earth and the Moon, often show the objects at a far larger scale than the distances between them. This image shows the Earth–Moon system to scale, which shows just how far away the Moon really is. In addition the Moon’s orbit is not a perfect circle: it’s sometimes closer, and sometimes further away from Earth. In fact, it looks around 14% larger and 30% brighter when at its closest to the Earth, known as perigee—and this is what often gets excitedly reported by the media as a ‘supermoon’, even though the difference is barely detectable to the human eye without something to compare it to. At its furthest, which astronomers call apogee, the Moon appears a little smaller than normal, sometimes known as a ‘mini-moon’.
This is actually most of the reason for the new Artemis record: while the chosen flight path takes the crew a few thousand kilometres beyond the Moon, the main factor is that lunar apogee this month is 404,973 km from the centre of the Earth at 08:33 UTC on April 7th, just a few hours after from Artemis’s maximum distance from Earth. If you compare the orange Artemis II line in the infographic above to the dark blue lunar apogee line, you’ll see that the crew weren’t that high above the Moon—but the Moon was almost as high as it could be above the Earth, giving the astronauts a record-setting boost.
The same is true of the crew of Apollo 13, the previous record-holders. After an oxygen tank exploded part-way to the Moon, the crew had to abandon their landing and instead loop around the far side of the Moon, following a trajectory that used the Moon's gravity to slingshot them back toward Earth using minimal fuel. Their flyby took them higher above the lunar surface than a normal Apollo orbit, but, just like Artemis II, the main reason they set a distance record was timing: the Moon happened to be near apogee. While they never got to walk on its surface, the Apollo 13 crew held the record for ‘furthest humans have ever been from Earth’ for more than 50 years.
Most amazing is quite how feeble the extent of human spaceflight is when seen on this scale: with the exception of this new Artemis flyby and the Apollo missions, the next furthest mission into space is represented by the stubby yellow line, less than the radius of the Moon.
We’ve sent probes into the Solar System, and even into deep space, and have a few satellites just over a tenth of the way to the Moon—but only a handful of people have ever been higher than 1,400 km. To paraphrase the page which inspired this diagram: of all the humans who have existed since the dawn of history, only 28 have ventured further than that tiny shell around our home planet. Seeing this to scale only makes the Moon landings more incredible—and this new phase of lunar exploration more exciting.
Further reading:
- Inconstant Moon, a page about the Moon’s complex orbit—including the diagram that inspired this one
- Lunar perigee and apogee calculator (aka supermoon calculator!)
- What is a supermoon? from NASA
- Wikipedia’s list of spaceflight records
- Apollo 13’s loop around the Moon described on Wikipedia