{"id":53399,"date":"2024-01-10T09:50:32","date_gmt":"2024-01-10T09:50:32","guid":{"rendered":"http:\/\/be696b66-d8a7-45ca-b5e4-6e69659657f7"},"modified":"2024-01-10T10:32:32","modified_gmt":"2024-01-10T10:32:32","slug":"the-reason-why-planets-are-round-explained","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/the-reason-why-planets-are-round-explained\/","title":{"rendered":"The reason why planets are round explained"},"content":{"rendered":"

Most planets and other bodies in the Solar System are nearly perfectly spherical, but why? <\/p>

By Maggie Aderin-Pocock\n <\/p>

Published: Wednesday, 10 January 2024 at 09:50 AM<\/p>

\n\n

From the major planets in our Solar System to the very Sun<\/a> itself, the sphere is the most common shape of celestial bodies, but why are the planets round?<\/p>

The short answer as to why the planets are around is simply gravity<\/a>!<\/p>

Gravity is the main force that sculpts the Universe, causing the formation of planets<\/a>, stars<\/a> and galaxies<\/a>.<\/p>

It works over great distances and has no preferred orientation.<\/p>

Gravity draws matter in from all directions, which clumps together and forms a round shape that looks the same from all directions. The shape that meets all these criteria is a sphere.<\/p>

Why are planets like our own Earth round? The simple answer is gravity. Credit: NASA\/Toby Ord<\/figcaption><\/figure>

Planets are not perfectly round<\/strong><\/h2>

Gravity may be the reason why planets are round, but it also distorts the sphere we would expect to see, so most of the bodies we think of as being round are really ‘almost spherical’.<\/p>

Take our planet for instance. If I was to travel all around the world from pole to pole, I would have covered a distance of around 39,941km.<\/p>

If I were to do the same journey, but this time around the equator, I would have travelled an additional 130km.<\/p>

The Earth bulges at the equator to form a shape close to an oblate spheroid \u2013 a slightly squashed sphere.<\/p>

Why planets are squashed<\/strong><\/h2>
\"The
The centrifugal force of a chairoplane is a simple way of understanding how a planet’s spin causes it to bulge, so it’s not perfectly round. Credit: Andrew Williams \/ EyeEm \/ Getty<\/figcaption><\/figure>

The reason why planets get a bit fat around the middle is due to their rotation about their axes.<\/p>

Imagine the chairoplane: that fairground ride with lots of chairs hanging down from a central disc.<\/p>

As the disc starts to rotate, the chairs lift and move outward from the centre or outward from the centre of rotation.<\/p>

The only thing stopping the chairs from flying off is the chains.<\/p>

The same thing happens to a planet when it spins. Gravity pulls everything inwards, but the speed of the rotation pushes everything outwards.<\/p>

Just like the chairs on the ride moving outward, as a plane rotates on its axis it grows wider around the middle.<\/p>