Hermanus: turn space weather into useful warnings

Space programs also operate on the ground. SANSA’s Space Science programme grew from the Hermanus Magnetic Observatory, which moved from Cape Town in 1941 to escape interference from electric railways. That history illustrates an experimental problem: a sensor can detect changes caused by nearby technology as well as changes in the environment being studied. A quiet site helps scientists distinguish the two.

The observatory became part of SANSA in 2011. Its modern work includes a continuously staffed space-weather centre, inaugurated in November 2022, and instruments that observe Earth’s magnetic field and ionosphere. SANSA’s ionosonde — open definition network includes Grahamstown, Louisvale, Madimbo and Hermanus. An ionosonde sends radio pulses through a range of frequencies and studies returning echoes, helping describe the ionized upper atmosphere through which radio signals travel.

A magnetometer measures magnetic-field changes; an ionosonde probes a different part of the Sun–Earth response. Neither instrument alone tells the whole story. Space-weather forecasters combine observations and models to assess conditions affecting communications and navigation. SANSA’s June 2026 aviation workshop emphasized translating those observations into information that operators can use, rather than merely reporting that the Sun was active.

Consider an invented bulletin issued at 08:00 UTC with an outlook valid until 20:00 UTC. A measurement collected at 07:30 describes an earlier observation; a prediction for 16:00 describes an expected future condition. At 09:00 the measurement is ninety minutes old even though the bulletin is only an hour old. Keeping measurement time, issue time and forecast validity separate prevents a freshly published page from making old observations appear new.

Three times in one bulletin

A solar flare, a disturbance in the solar wind and a change in Earth’s ionosphere are related phenomena, but they are not interchangeable descriptions. An advisory about high-frequency radio does not automatically mean that every satellite has failed. The useful questions are which system is affected, where, for how long, and with what uncertainty. Local measurements help place a global event in the context of actual users.

For a classroom investigation, compare two dated bulletins and record the observed conditions separately from the outlook. Later observations can help evaluate the prediction, provided their place, time and measured quantity match. A warning that includes uncertainty can still be useful: it gives a user reason to prepare or seek updated information. This exercise teaches interpretation of evidence; actual aviation decisions follow the operator’s approved procedures and current official advisories.