How far is the Moon? Visualizing the distance

It's not exactly accurate, but it's a dazzling display.

The distance between the Earth and the moon is 384,400 km (240,000 miles) — we’re taught that in high school, and even if we don’t know it, it’s always easy to look it up on the internet.

But knowing and comprehending this distance are two entirely different things. Now, you can truly see it, thanks to this image from NASA’s OSIRIS-REx spacecraft.

At the time this image was taken, the spacecraft was retreating from Earth after performing an Earth Gravity Assist maneuver on Sept. 22. Earth and the Moon are shown 249,000 miles (401,200 kilometers) apart, and the spacecraft is 804,000 miles (1,297,000 kilometers) from Earth and 735,000 miles (1,185,000 kilometers) from the Moon. At this range, both bodies could be captured in the same image. Image credits: NASA/Goddard/University of Arizona.

OSIRIS-REx is a NASA asteroid study-and-sample-return mission. Its goal is to reach and sample an asteroid called 101955 Bennu, and return a sample to Earth by 2023 for detailed analysis. But once again, NASA spoils us with something extra. This time, it’s a composite image of the Earth and the Moon.

Made from data captured by OSIRIS-REx’s MapCam instrument on October 2, 2017, the image was taken at about 3 million miles (5 million kilometers) from Earth, roughly 13 times the distance between the Earth and its Moon. Three images shot at different wavelengths were combined and color-corrected to create the result we see above. The moon was brightened to make it more clearly visible.

However, the image is somewhat deceptive. Although OSIRIS’ angle offers a great view of the two celestial bodies, it isn’t perfect. Specifically, the location of the shuttle was not perpendicular to the Earth-Moon axis, which means that the perspective is a bit skewed. In this case, the obtuse angle is about 142°, which is quite different from the 90° angle which would have created a perfect image.

The angle between the three objects is 142° — 90° would be required for non-distorted perspective.

A good rule of thumb is that you could fit about 30 Earths in the space between our planet and the Moon. But if you’d copy and paste the Earth in NASA’s image, you’d see that you can only fit about 20 Earths in there, meaning you see about two-thirds of the real distance here. Nevertheless, it remains an impressive feat, a vivid visualization of an ungodly distance.

However, this isn’t the only photo of its kind. About one year ago, NASA’s Mars Reconnaissance Orbiter sent back an even broader photo that captured the Earth and Mars in the same frame. You can see the humbling image here.