# The Sun and its worlds

> Our star and its weather, the planets, the rocks we watch, and the craft we sent out.

HTML: https://www.theuniversecounts.com/solar-system

Numbers as of 2026-10-31 02:42 UTC. Live ones keep changing on the HTML page.

- Solar wind speed measured upstream of Earth: 344 km/s
- Planetary K-index (Kp), latest 3-hour value: 4.33
- Time for light from Earth to reach Voyager 1: 23 h 57 m 27 s

## Sources

- Earth's circumference at the equator (Measured): [NASA NSSDCA: Earth Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html)
- Great-circle distance between London and Sydney (Measured, with error): [NASA NSSDCA: Earth Fact Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html)
- Planetary K-index (Kp), latest 3-hour value (Measured, with error): [NOAA SWPC: Planetary K-index](https://www.swpc.noaa.gov/products/planetary-k-index); [NOAA SWPC: NOAA Space Weather Scales](https://www.swpc.noaa.gov/noaa-scales-explanation)
- Solar wind speed measured upstream of Earth (Measured): [NOAA SWPC: Solar Wind Data and Display Changes (30 June 2026)](https://www.spaceweather.gov/news/solar-wind-data-and-display-changes); [NOAA SWPC: SWPC home-page summary bar script (shows this file as "Solar Wind Speed ... km/sec")](https://www.swpc.noaa.gov/modules/custom/swpc_summary/swpc_summary.js); [The Astrophysical Journal: Extremely Slow (Vsw < 300 km/s) Solar Winds (ESSWs) at 1 au: Causes of Extreme Geomagnetic Quiet at Earth (Tsurutani & Hajra 2022, ApJ 936, 155)](https://doi.org/10.3847/1538-4357/ac7444); [Journal of Geophysical Research: Extremely high speed solar wind: 29-30 October 2003 (Skoug et al. 2004, JGR 109, A09102)](https://doi.org/10.1029/2004JA010494); [Space Weather (AGU): On the Little-Known Consequences of the 4 August 1972 Ultra-Fast Coronal Mass Ejecta (Knipp et al. 2018, Space Weather 16)](https://doi.org/10.1029/2018SW002024)
- The Moon's average distance from Earth (Measured): [NASA: Moon Facts](https://science.nasa.gov/moon/facts/)
- Time for light from Earth to reach Voyager 1 (Measured): [NASA JPL: Horizons API documentation](https://ssd-api.jpl.nasa.gov/doc/horizons.html)