Frequently Asked Questions

What is the role of our Space Weather Centre?

To deliver space weather products and services that meet the evolving needs of the nation. The SANSA Space Weather Centre gathers, in real time, the available data that describes the state of the Sun, Heliosphere, Magnetosphere, and Ionosphere to form a picture of the environment from the Sun to the Earth. With this information, forecasts, warnings and alerts are prepared by the Space Weather Centre and issued to anyone affected by space weather.

Can space weather affect life on Earth?

Although space weather can pose a health risk for astronauts in space, it will not harm humans and other life forms on Earth as we are protected by the Earth’s magnetic field. Space weather can cause a geomagnetic storm, which can result in disturbances to technological systems such as GPS, radio communications, internet, cell phones, DStv and our electrical power grids.

How do you monitor events on the Sun?

Space Weather Centre forecasters utilise a variety of ground and space-based sensors and imaging systems to view activity at various depths in the solar atmosphere.

What are coronal holes?

Coronal holes are large holes in the Sun’s corona (caused by 'gaps' in the magnetic field) that are less dense and cooler than surrounding areas. High-speed solar wind streams flow through coronal holes into space at speeds of up to 800 km per second.

What are sunspots and how do they relate to space weather?

Sunspots are temporary phenomena on the surface of the Sun that appear as dark spots compared to surrounding regions due to a temperature difference of the sunspot . A moderate-sized sunspot is about the size of the Earth.
Sunspots form and dissipate over periods of days or weeks. A typical sunspot consists of a dark central region called the umbra and somewhat lighter surrounding region called the penumbra.
Sunspots usually occur in groups or in pairs and at times in complicated arrangements with many spots and complex shapes.
These unusual regions most often produce solar flares and Coronal Mass Ejections (CMEs). Space weather forecasters use the complexity and shapes of sunspots to make flare forecasts - the more complex the groups of spots, the more likely a flare will occur.

What is a geomagnetic storm?

A geomagnetic storm is a temporary disturbance of the Earth's magnetosphere. It can be caused by a solar wind shock wave or the magnetic field of a Coronal Mass Ejection (CME) which interacts with the Earth's magnetic field.

What is a satellite?

A satellite is a moon, planet or machine that orbits a planet or star. Earth is a satellite because it orbits the Sun so is the moon because it orbits Earth. Earth and the moon are examples of natural satellites. Usually, the word "satellite" refers to a machine that is launched into space and moves around Earth or another body in space. Thousands of artificial, or man-made, satellites orbit Earth. Some take pictures of the Earth that help predict weather and track hurricanes. Some take pictures of other planets, the Sun, black holes, dark matter or faraway galaxies. These pictures help scientists better understand the solar system and universe.
Satellites are mainly used for communications, such as beaming TV signals and phone calls around the world. A group of more than 20 satellites make up the Global Positioning System, or GPS. If you have a GPS receiver, these satellites can help figure out your exact location.

What is solar maximum and solar minimum?

The Sun goes through two 11-year cycles of solar activity. Solar minimum refers to a period when the number of sunspots is lowest, bringing less solar activity. Solar maximum is the period when the number of sunspots is highest, bringing more frequent solar activity and a greater likelihood of solar flares.

The Sun is currently in a solar maximum cycle which is expected to peak in 2013/2014.

What is the "South Atlantic Anomaly"?

The South Atlantic Anomaly (SAA) is a dip in the Earth's magnetic field which allows cosmic rays and charged particles to reach lower into the atmosphere. The SAA is populated with high energy particles that can cause upsets in satellite electronics.

What satellites provide space weather data?

Why are satellites important?

The bird's-eye view that satellites have allows them to see large areas of Earth at one time. This ability means satellites can collect more data, more quickly, than instruments on the ground.

Satellites also can see into space better than telescopes at Earth's surface. That's because satellites fly above the clouds, dust and molecules in the atmosphere that can block the view from ground level.

Before satellites, TV signals didn't go very far. TV signals only travel in straight lines. So they would quickly trail off into space instead of following Earth's curve. Sometimes mountains or tall buildings would block them. Phone calls to faraway places were also a problem. Setting up telephone wires over long distances or underwater is difficult and costs a lot.

With satellites, TV signals and phone calls are sent upward to a satellite. Then, almost instantly, the satellite can send them back down to different locations on Earth.

Why is forecasting space weather important?

Forecasting plays a vital role in protecting ground and space-based technological systems. Specific effects of space weather on technological systems include interference with short wave radio propagation and electric power grids, the decay of satellite orbits, radiation hazard for satellites and for astronauts during some phases of space missions.

What solar parameters should I use for my prediction software?

On our Forecasts and Predictions page we provide several solar parameters and indices for the next 3 days.

Unless stated otherwise, all T-indices on this website are those smoothed for the day and adjusted for local conditions, and so are suitable for use with ASAPS and WASAPS software.

If you are using IONCAP/ICEPAC/VOACAP software for near real-time Ionospheric evaluations, we recommend using the Solar Index (Se), also known as effective SSN or WCI (Wind Compensated Index).

Should you require more than 3 days of indices, please feel free to Contact Us to discuss further requirements.

Have another question?

If there are any other questions that you have about space weather, please feel free to Contact Us directly, or by using our Feedback form and we will do our best to answer you!