Is there a ninth planet in our solar system?

From Dr Malena Rice’s Garden Talk “Are we missing a planet in our solar system?
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Planet nine is the hypothetical planet that we believe may be hiding in the solar system. Its existence is assumed based on the witnessed gravitational influence on a group of small, very distant objects with elongated, clustered orbits.

However, due to how far away planet Nine would be from the sun, it's likely that it would reflect very little sunlight thus can evade telescopes.

In order to defined as a planet, it must meet three criteria:

1. It must orbit a star, and not another planet

2. It must be spherical

3. It must clear its orbit, meaning that when it orbits it can push all the smaller bodies out of it's way making in the primary gravitational force in that ring

Pluto, for example, didn't meet this third criteria meaning its not longer considered out ninth planet.

Learn more about this with our series “The Bright Night Sky”

For centuries, we have been looking up to the sky to understand the mysteries that surround us. The sky might hold the answers to some of our deepest questions such as where we came from. But what do we know so far?

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