On December 2, 1995, NASA and the European Space Agency (ESA) launched a small spacecraft to stare at the Sun.
For the past 25 years, the Solar and Heliospheric Observatory (SOHO) satellite has been creeping on our host star, studying its every move and taking note of the Sun's activity. Using footage from the observatory's years in operation, ESA has compiled a time-lapse video showing what two and a half decades of the Sun looks like, as the star emits powerful solar flares and coronal mass ejections into space.
The video was released Wednesday, and merges footage from the C2 and C3 cameras of the LASCO instrument onboard SOHO from the year 1998 to 2020.
In the footage, the Sun is constantly erupting with solar wind, coronal mass ejections, and solar flareups, which are all part of the Sun's activity.
Solar activity largely depends on the Sun's magnetic field. The Sun’s magnetic field goes through a periodic cycle in which the south and north poles essentially switch spots, and it takes another 11 years or so for them to switch back.
What stage the solar cycle happens to be in is revealed by changes in the Sun's activity. The Sun periodically ejects boiling-hot plasma, flinging ionized material and radiation across Solar System.
During the video, viewers can see some of this material aimed in the direction of SOHO at nearly the speed of light, resulting in brief moments of white noise in the footage.
These ejections can also cause magnetic storms in the Earth's upper atmosphere, which can have major effects on the power grids on Earth, as well as orbiting spacecraft and astronauts. When these solar flares reach Earth, they penetrate through Earth's protective layer of the atmosphere, known as the magnetosphere, and wreak havoc on our electric equipment and power grids.
On August 7, 1972, a massive solar storm erupted from the Sun's surface, disrupting radio waves, telecommunication networks, and power systems by triggering an intense magnetic storm on Earth.
“The reason why SOHO is flying now is for space weather research – to understand how the Sun impacts the earth,” Bernhard Fleck, ESA’s SOHO project scientist and mission manager, said in a statement.
SOHO hovers 1.5 million kilometers closer to the Sun than the Earth, getting a more up-close and personal view of the star. This relative closeness allows SOHO to study the structure of the Sun's interior, its outer atmosphere — known as the Sun's corona — and solar wind.
Since its launch, the data collected by SOHO has been used in almost 6,000 studies on solar activity.
SOHO has also played a vital role in protecting us from harmful space weather. Using the Large Angle and Spectrometric Coronagraph instrument, which studies the structure and behavior of the Sun's corona by creating an artificial solar eclipse, space weather forecasters on Earth can see when solar storms are headed towards our planet one to three days before they arrive.
Although it launched nearly two and a half decades ago, SOHO remains on the forefront of the study of the Sun, providing constant and invaluable data about the star.
“The world was very different 30 years ago, yet they built such a solid piece of hardware that it still works, and has instruments that are still relevant, 30 years later. That is quite amazing,” Bernhard said.