Space physics, or solar-terrestrial physics, deals primarily with the interaction of electric and magnetic fields with high-energy charged particles in outer space. Charged particles from the solar wind constantly ejecting from the Sun create a space plasma throughout the heliosphere. Whether we send or place spacecraft satellites or space stations anywhere in the solar system, everything has to move inside this plasma. Just as you need to know the science of the atmosphere to make airplanes that can move in the Earth’s atmosphere, so to make spacecraft and satellites that can move in the heliosphere of the solar system, you need to understand the science of the heliosphere, and this science is called space physics.

Before the beginning of the space age, space physics was mainly done by observing and detecting various processes in the upper part of the Earth’s atmosphere. But currently most of the research on this subject is done by collecting data directly from the sites of the most intense interactions with rockets and spacecraft. Instruments used for collection include cameras, photometers, spectrometers, magnetometers. Although the face of this field has changed completely in the last hundred years, its history is very old, since people were fascinated by the aurora, surprised by the attraction of magnets, since the beginning of space physics.

Space physics began because of human interest in two things on Earth: auroras and geomagnetism. Evidence of seeing the aurora existed long ago, but the existence of geomagnetism was not understood before the invention of the compass. There are references to Aurora in the scriptures of many nations of the world. Two and a half thousand years ago, Xenophenes of Greece defined the aurora as a ‘moving mass of burning clouds’. Chinese records date back more than four thousand years to aurora sightings.

There were many superstitions and fears about Aurora. The first scientific inquiry into it began in the seventeenth century in Europe. Galileo proposed that the aurora is formed when sunlight hits the air rising from the Earth’s shadow. He also coined the term ‘Aurora Borealis’ to mean the northern aurora. French philosopher-priest Pierre Gassendi realized that the aurora is a phenomenon far above the Earth’s surface, because the aurora looks the same from two distant places. At the same time Ron Descartes attributed the aurora to the reflection of light from the ice in the area near the North Pole. In the latter half of the seventeenth century, both the activity of the sun and the aurora decreased greatly.

In the 18th century, Edmund Halley hypothesized a geomagnetic relationship with the aurora. But the French philosopher de Meran disagreed with Halley on the connection of the sunspot with the aurora. Since then, aurora research has been closely associated with geomagnetism. The first allusion to the existence of geomagnets is found in an eleventh-century Chinese treatise on the compass. In the twelfth century, books were written about geomagnets and compasses in Europe as well, in which sailors used compasses to determine the direction of north on cloudy days. By the fourteenth century, many ships were using a regular compass.

The difference (called declination) between the direction of the magnetic pole and the geographic pole varies from place to place on Earth. Not sure when it was first understood. But in a letter written in Europe in the sixteenth century, it is said that the declination of Rome is 6 degrees and the declination of Nuremberg in Germany is 10 degrees.