Decreasing Speed

* Elliptical Orbit: Planets don't travel in perfect circles. They follow elliptical paths. When a planet's speed decreases, it will move further away from the Sun as it reaches its farthest point in its orbit (called aphelion).

* Slower Orbital Period: The time it takes to complete one full orbit (a year) will increase.

* Conservation of Energy: The planet's total energy (kinetic energy from its speed + potential energy due to its distance from the Sun) remains constant. As speed decreases, the planet gains potential energy by moving further away from the Sun.

Increasing Speed

* Elliptical Orbit: When a planet's speed increases, it will move closer to the Sun as it reaches its closest point in its orbit (called perihelion).

* Faster Orbital Period: The time it takes to complete one full orbit will decrease.

* Conservation of Energy: As the planet's speed increases, it loses potential energy by moving closer to the Sun, but gains kinetic energy.

Important Note: These changes in speed are not random events. They are governed by the laws of gravity and the conservation of energy. A planet's speed naturally changes throughout its elliptical orbit.

Examples:

* Earth's Orbit: Earth is slightly faster when it's closer to the Sun in January (perihelion) and slower when it's further away in July (aphelion).

* Comets: Comets often have very elliptical orbits. They travel very quickly when close to the Sun and much slower when far away.

Let me know if you'd like to delve deeper into any of these concepts or have other questions about planetary motion!