Nunki is a real star, and it is in the video on the homepage. The video was shot in the Florida Keys on June 30, 2026, at 9:33 pm. Nunki was low in the southeast, about 11 degrees above the water. The chart is that sky, with every star the phone caught drawn where the phone caught it.
1798 · 228 light-years to go
The light leaves
The light in the video left Nunki around 1798. The star is 228 light-years away, give or take 5, so the phone recorded Nunki as it was while John Adams was president.
Two stars sent it. Nunki is a pair of blue-white stars, each about six and a half times the mass of the Sun and three times as hot, circling each other every 135 days. They are so close together that astronomers only confirmed there were two in 2025. From here they are one point of light, the second-brightest star in Sagittarius, at the top of the Teapot’s handle.
They are about 30 million years old, which is young for a star. Of all the stars expected to end as a supernova, Nunki is the closest candidate to us.
1802 · 224 light-years to go
How to steer by it
The light was 4 years out when Nathaniel Bowditch published The New American Practical Navigator, in 1802. The book is still in print, and it lists 57 stars to navigate by. Nunki is number 50.
A star sight starts with a sextant. You measure how high the star is above the horizon and write down the second you did it.
An almanac gives the one spot on Earth the star was straight above at that second. If the star is straight up, you are standing on that spot. For every degree it is short of straight up, you are 60 nautical miles away from it, which puts you somewhere on a circle.
In the Keys that night a sextant would have read 10°46′. Take off 5′ for the bend the air puts in the light, and Nunki was 79°19′ short of straight up. It was straight above a spot in the South Atlantic, at 26° S, 18° W, so the Keys were 4,759 nautical miles from there.
The video would do for the clock. Its file is stamped to the second.
1953 · 73 light-years to go
The name
By 1953 all 57 of the navigator’s stars had a common name. Nunki’s is Sumerian. It meant the star of Eridu, a city, and it belonged to a different part of the sky. A misreading of the clay tablets in the 1800s moved it to Sagittarius, a popular book of star names repeated it in 1899, and it is the name on the navigators’ list. The International Astronomical Union has since made it official.
1968 · 58 light-years to go
To the moon
Apollo 8 left for the moon in December 1968 with a sextant built into the spacecraft and a list of 37 stars in its computer. The computer kept track of which way the ship was pointing, its sense of that drifted, and the crew corrected it by sighting stars. Nunki is on the list, as star 37.
The moon is the other thing in that sky you can click.
June 30, 2026, 9:33 pm · 0 light-years to go
The light arrives
After 228 years the light came in low over the water from the southeast and ended in a phone. The light that left Nunki that same night gets here around 2254.
End of entry. T.M. Back to the night
Sources
- The distance, from a parallax of 14.32 ± 0.29 thousandths of an arcsecond: F. van Leeuwen, Validation of the new Hipparcos reduction, Astronomy & Astrophysics 474 (2007)
- The two stars, their masses and their orbit, and the supernova: I. Waisberg and B. Katz, Confirming Nunki as the closest core collapse progenitor candidate to the Sun (2026)
- Its brightness, temperature and age, and the 2025 measurement of the pair: Sigma Sagittarii, Wikipedia, and the papers it cites
- The 57 stars, Nunki as number 50, and their names since 1953: List of stars for navigation, Wikipedia, from Bowditch, The American Practical Navigator (2002), p. 249
- Bowditch's first edition, 1802: American Practical Navigator, Wikipedia
- The name, and how it came to this star: Nunki, All Skies Encyclopaedia, IAU Working Group on Star Names
- Apollo's 37 stars, with Nunki as star 37: Apollo 8 CMP Checklist (1968), star list, from the Virtual AGC project
- Where the stars were: positions and magnitudes: The Hipparcos Catalogue (ESA, 1997), from VizieR, with the sky of that night worked out by Astronomy Engine
- The coastlines on the globe: Natural Earth, 1:110m land