Objects On and From the Sun


Sunspots appear as dark patches in the solar photosphere. These are areas where strong magnetic field has emerged from below the solar surface. The strong magnetic field suppresses the release of heat into the photosphere making sunspots cooler than their surroundings. Because they are much cooler than the surrounding photosphere sunspots appear darker even though they are still many 1000s of degrees Celsius.


Sometimes magnetic field in the solar atmosphere holds up solar plasma from the chromosphere into the solar corona. The filaments are held up in a kind-of magnetic hammock. The relatively cool filament material appears dark when observed against the bright solar disk. Filaments can stretch far across the Sun measuring 100s of thousands of kilometers. The equivalent of 10 or more Earths lined up in a row.


Prominences are really just the same thing as filaments only viewed from a different perspective. Filament are seen on the solar disk however filament are very high up in the solar atmosphere, way above the surface. So when a filament is on the edge of the Sun the filament sticks out with space instead of the solar surface behind it. This makes the filament very bright compared to the dark (cold) background of space. We call a filament viewed this way a prominence. They can be simple looped shaped object or very irregular with a complicated structure.

Solar Wind

The outer corona is heated up to such high energies that it eventually expands away from the Sun as a stream of electrons, protons and other atomic particles. The stream travels away from the Sun at speeds of around 200-400 km/s but can reach speeds of 900 km/s. The solar wind fills the entire solar system so all the planets sit inside the outer solar atmosphere. We live inside the atmosphere of a star. Sometimes concentrated high-speed solar wind streams come from the Sun and impacts the Earth. These can produce magnetic disturbances in the Earths upper atmosphere called a geomagnetic storm and produce the Southern and Northern Lights (The Aurora).

Coronal Holes

Coronal Holes are areas on the Sun that appear dark when observed in Extreme Ultraviolet and x-ray light. They are regions where the magnetic field on the solar surface opens up into space making it easier for coronal material to escape. Because these areas have less corona, they have less material to emit light and so appear dark compared to the rest of the corona. Coronal holes are believed to be the origin of the high-speed solar wind. They occur mostly near the north and south poles but they can occur at other places on the solar disk.

Solar Flares

Solar flares are a sudden, explosive release of magnetic energy in the form of electromagnetic radiation (most of the light spectrum, from radio waves to gamma-rays) and very fast atomic particles. Solar flares occur in regions of concentrated magnetic field such as sunspots.

Coronal Mass Ejections (CMEs)

Sometimes when magnetic energy is released the corona becomes so disturbed that large pieces of it are released into space. Billions of tons of solar material and magnetic field are hurled from the Sun into interplanetary space at speeds up to several million mph. As they move away from the Sun they expand becoming as wide across as the distance from the Earth to the Sun. CMEs can occur when filaments/prominences become unstable and fly away from the Sun. We call this a filament/prominence eruption.

Solar Energetic Particles (SEPs)

When a large solar flare or CME occurs they can accelerate a large number of atomic particles, electrons, protons and various elements to very high energies. When SEPs impact the cameras on a spacecraft the recorded images look like a television screen with a lot of static or snow.