Imagine if our solar system suddenly lost a few moons, or even a planet. You might think such an event would dramatically alter our cosmic neighborhood, but the impact could potentially go unnoticed. However, losing the sun would be a completely different story, as it is the central anchor of our solar system. Despite its crucial importance, many aspects of the sun’s functionality and its effects on Earth and space remain enigmatic. The year 2025 is set to be pivotal in deepening our understanding of these mysteries.

The upcoming year is shaping up to be thrilling for heliophysics, the study of the sun, due to three key developments: the peak of the sun’s activity cycle, an array of scheduled spacecraft launches, and the release of a strategic plan that will direct research in this field over the next decade.

Currently, the sun is at the apex of its 11-year activity cycle, expected to stay in this high-activity phase for about another year before calming down. Although Solar Cycle 25 isn’t setting any records, it has generated numerous solar flares and other impressive phenomena, which have been monitored using newly developed instruments. These tools include the largest solar telescope ever constructed and a spacecraft that has ventured closer to the sun than any before it.

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In addition, this year promises the introduction of several innovative projects; NASA alone is planning to launch around six missions focused on studying the sun and its extensive influence on the solar system. These missions include the Interstellar Mapping and Acceleration Probe (IMAP), which aims to chart the boundaries of the sun’s influence; the Escape and Plasma Acceleration and Dynamics Explorers (ESCAPADE), a duo of spacecraft set to orbit Mars and examine its space weather conditions; and the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission, intended to study the sun’s outer atmosphere using four small satellites orbiting Earth.

Furthermore, American heliophysicists have recently been furnished with a new decadal survey, a comprehensive strategy for the next ten years that outlines key scientific priorities. This plan was released last month and will soon begin to be implemented by federal agencies. “I’m really excited about it,” states Joe Westlake, a heliophysicist and the director of the Heliophysics Division at NASA’s Science Mission Directorate.

“These decadal surveys provide a visionary outlook for our future,” he explains. “There’s some really exciting content in this one.”

For upcoming spacecraft missions, the survey suggests that NASA should undertake two major initiatives. One involves deploying a total of 26 spacecraft, with two stationed in circular orbits high above Earth’s poles to capture images of auroras and the planet’s magnetic field, and the others in more elliptical orbits to collect localized data on the geomagnetic field and surrounding plasma. “Having over twenty spacecraft working simultaneously to collect data from different perspectives will provide an invaluable dataset,” remarks Nicki Rayl, acting deputy director of the Heliophysics Division. “I believe it will be revolutionary.”

The other major initiative involves a spacecraft designed to fly repeatedly over both the sun’s poles during a full 11-year solar activity cycle. Although NASA’s Parker Solar Probe has been progressively approaching the sun, it has focused on the equatorial regions. The European Space Agency’s Solar Orbiter, meanwhile, has only offered limited views of the solar poles. These regions remain largely unexplored, yet they are crucial to understanding the sun’s magnetic field dynamics. “Exploring the poles of the sun is challenging and the environment is difficult to navigate,” Rayl notes. “That’s the next frontier we’re aiming to reach.”

On Earth, these ambitious missions will be complemented by the Next Generation Global Oscillations Network Group (ngGONG), an expansion of the existing GONG network of observatories that began operations in 1995. Positioned around the globe to maintain constant observation of the sun, they employ helioseismology to probe the solar interior by tracking waves traveling through it, similar to how geologists use seismology to examine Earth’s interior.

“The bold, incredible goals outlined in the decadal survey are pushing us into new territories and fostering discovery science,” Rayl asserts. In the meantime, the upcoming launches over the next year are expected to yield further insights and raise new questions about the sun. “I’m just excited that we’re entering a phase of active data collection,” she concludes. “It’s go time.”