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What are Lagrange Points?

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We Asked a NASA Scientist.

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Lagrange Points,
 named after the Italian astronomer

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who first proposed
 them, are places in our solar system

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where the gravitational
 pull of the planet and the Sun,

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and the motion of the orbit combine
 to create an equilibrium.

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So it takes very little energy
 to retain that orbit.

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Objects that are sent
 to these locations in space either

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tend to stay there
 naturally or can be kept there

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with minimal energy
 because the forces are in balance.

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NASA's taking advantage
 of those Lagrange points to send

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extraordinary missions
 like the James Webb Space Telescope,

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which will orbit the Sun at Earth's
 Lagrange Point number two,

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allowing the telescope to stay in line
 with Earth as it moves around the Sun

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and retain that orbit
 using very little fuel.

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NASA's Lucy mission will study
 the pristine Trojan asteroids,

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the remnants of our solar system
 that have been gravitationally trapped

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around Jupiter's
 Lagrange Point number four and Lagrange

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Point number five for over four
 and a half billion years.

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So, what are Lagrange Points?

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They are places in our solar system
 where objects can orbit

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the Sun at the same speed as a planet

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staying in the same place
 relative to both of them.