And just like us, it goes through phases and changes. Over time, these changes in our star have become more predictable. Currently, he is going through a less active phase phase, called a solar minimum.
The sun experiences regular 11-year intervals, including peaks in energy activity, followed by low points.
During the peak, the sun has more sunspots and solar flares.
In a solar minimum, the sun is much quieter, which means less sunspots and less energy.
NASA scientists say that we are currently in a “Great minimum solar”. The last time this happened was between 1650 and 1715, during what is known as the Little Ice Age in the northern hemisphere of Earth, “when the combination of the cooling of volcanic aerosols and the Low solar activity has produced lower surface temperatures, ”according to NASA’s Global Climate Change blog.
But this solar minimum will not trigger another ice age, they say. And this is probably due to climate change.
“The warming caused by greenhouse gas emissions from human combustion of fossil fuels is six times greater than the possible cooling over several decades of an extended Great Minimum Minimum,” they wrote.
“Even if a Great Solar Minimum were to last a century, global temperatures would continue to warm. Because more factors than variations in the production of the Sun modify global temperatures on Earth, the most dominant of those today is human-caused global warming. “
Scientists know that this solar minimum is coming, because it is a regular aspect of the sun’s cycle. Sunspots peaked in 2014, with low points starting in 2019, according to NASA.
The sun is also responsible for what is called space weather, sending particles and cosmic rays streaming through our solar system. The sun’s highly magnetized sunspots release solar flares, which can send X-rays and ultraviolet rays rushing towards Earth.
Even when the sun is calm during the solar minimum, it can be active in various ways, such as coronal holes which open in the sun’s atmosphere and send out flamboyant streams of energized particles flying through the solar system through a fast solar wind.
Like solar flares, these particle flows during a solar minimum can disrupt communication and GPS on which we depend on satellites.
“We see these holes throughout the solar cycle, but during the solar minimum, they can last a long time – six months or more,” said Dean Pesnell, project scientist at the Observatory for Solar Dynamics at Goddard Space Flight Center from NASA in 2017. NASA blog article.
More highly energetic particles called galactic cosmic rays can reach the Earth, in particular its upper atmosphere, during a solar minimum. These are created by explosions across our Milky Way galaxy, like supernovae.
“During the solar minimum, the sun’s magnetic field weakens and provides less protection against these cosmic rays,” said Pesnell. “This can pose an increased threat to astronauts traveling in outer space. “
This week, the NASA Sun & Space account shared this on Twitter amid concerns about the solar minimum. “The Sun goes through regular cycles of high and low activity. This cycle affects the frequency of space weather events, but it has no major effect on Earth’s climate – even a prolonged minimum would have no significant effect on global temperature. ”
This solar minimum ends the solar cycle 24. According to the first forecasts, the peak of the solar cycle 25 would occur in July 2025, according to the National Oceanic and Atmospheric Administration.
The solar cycle forecasts are based on an international panel co-chaired by NOAA and NASA. They agree that the solar cycle 25 will be similar to cycle 24.
Study the sun
In August 2018, NASA launched the Parker solar probe to get closer to the sun than any other satellite before. This is a unique opportunity to study “the star in our backyard,” as NASA heliophysics director Nicola Fox says. And it witnesses the sun during the solar minimum up close.
The probe was designed to help answer fundamental questions about the solar wind coming out of the sun, projecting energetic particles through the solar system. His instruments can also explain why the solar corona, the star’s outer atmosphere, is so much warmer than the actual surface. The crown is 1 million Kelvin, while the surface is approximately 6000 Kelvin.
Understanding the solar wind and the fiery heat of the crown is essential. They both play a role in space weather and solar storms, and understanding the solar wind could allow better prediction of space weather.
The solar wind and the temperature of the corona also have an impact on mass ejections from the corona, which could have an impact on the global electrical network and telecommunications on Earth, as well as on our astronauts on the International Space Station. The energized and accelerated particles that escape from the sun in the solar wind are also responsible for the north and south lights that we see on Earth.
Some of the first results of the first passages of the probe around the sun have already proved intriguing.
During its first close encounter with the sun, the Parker solar probe essentially remained suspended above a hole in the crown for a week, watching the particles of the solar wind flow along the line of the magnetic field of the sun and in space.
“It’s amazing – even under minimal solar conditions, the sun produces many more tiny energy particle events than we thought,” said David McComas, principal investigator for the Integrated Science Investigation of the Sun suite, or ISʘIS , at Princeton University in New Jersey. , in a press release when the first results were published. “These measures will help us unravel the sources, acceleration and transport of solar energy particles and, ultimately, better protect satellites and astronauts.”
During the probe’s seven-year mission, its orbit will shrink, bringing it closer and closer to the sun during 21 approaches.
The probe will orbit less than 3.9 million miles from the surface of the sun in 2024, closer to the star than Mercury. Although it sounds far away, the researchers equate it with the probe sitting on the four-meter line of a football field and the sun being the end zone.