The L1 Lagrange point, also known as the first Lagrange point, is a location in space where the gravitational forces of two large bodies, such as the Earth and the Moon or the Earth and the Sun, balance the centripetal force felt by a smaller object. This results in a stable point in space where the gravitational pull of these bodies cancels out, allowing a smaller object to effectively "hover" in place relative to them.
Specifically, the L1 Lagrange point is located on the line connecting the two larger bodies and is farther from the smaller body (e.g., the Earth) than either of the large bodies. In the case of the Earth-Sun system, the L1 point is positioned on the line connecting the Earth and the Sun, but it's about 1.5 million kilometers (about 930,000 miles) away from Earth in the direction of the Sun.
The L1 Lagrange point has proven to be strategically advantageous for various space missions. Spacecraft positioned at this point can maintain a relatively constant distance from both the Earth and the Sun, enabling continuous observation without interruptions caused by Earth's shadow or other celestial bodies.
For solar observation missions like Aditya-L1, the L1 point offers an unobstructed view of the Sun, allowing for comprehensive study of solar activities and phenomena. Similarly, the L1 point has been chosen for other space missions, such as solar wind monitoring, space weather observations, and certain types of astronomical observations, due to its unique position and stability in the Earth-Sun system.
