{"id":54158,"date":"2024-01-19T08:24:22","date_gmt":"2024-01-19T08:24:22","guid":{"rendered":"http:\/\/4a32d9e4-10c9-4107-9040-ea245d4f9396"},"modified":"2024-01-19T09:33:56","modified_gmt":"2024-01-19T09:33:56","slug":"gravity-in-space-despite-what-you-may-think-theres-loads-of-it","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/gravity-in-space-despite-what-you-may-think-theres-loads-of-it\/","title":{"rendered":"Gravity in space? Despite what you may think, there’s loads of it"},"content":{"rendered":"

The force we call gravity is everywhere and affecting everything. <\/p>

By Russell Deeks\n <\/p>

Published: Friday, 19 January 2024 at 08:24 AM<\/p>

\n\n

Astronauts float because there’s no gravity in space, right? Wrong! There\u2019s absolutely loads of gravity in space.<\/p>

In fact were it not for gravity, space as we know it \u2013 with all its stars<\/a>, planets<\/a>, asteroids<\/a>, comets<\/a>, nebulae<\/a>, pulsars<\/a> and so on \u2013 wouldn\u2019t exist at all.<\/p>

Gravity<\/a> is what caused all these objects to form in the first place, it\u2019s what prevents them from falling apart, and it explains their relative positions.<\/p>

And in any case, astronauts on the ISS aren’t floating because there’s no gravity; they’re floating because they’re continuously falling (as they orbit Earth).<\/p>

There is gravity on the International Space Station! Gravity is pulling it towards Earth: it just cleverely keeps dipping over the horizon so that it ‘orbits’ Earth. ISS astronauts are constantly free-falling. Credit: NASA\/Roscosmos<\/figcaption><\/figure>

The problem is that, being but simple Earth-dwelling, carbon-based lifeforms, we tend to misunderstand gravity, and think of it as the force that means ‘what goes up, must come down’.<\/p>

Gravity is the invisible power that means if the cat pushes your mug off the table, that mug will fall to Earth every single time, isn’t it?<\/p>

In reality, gravity isn\u2019t a force that Earth exerts on the people, animals and objects on its surface.<\/p>

Rather, gravity is a force that every object with mass in the entire Universe exerts on every other object with mass in the entire Universe<\/strong>.<\/p>

How powerful that force is, is determined by the size of the two objects in question, and their distance apart.<\/p>

\"Does
Does gravity cause a mug to fall? The answer is yes and no! Credit: Leonello Calvetti \/ Science Photo Library \/ Getty Images<\/figcaption><\/figure>

In the example of the mug above, Earth has many million times more mass than the mug, so while the mug is ALSO doing its best to pull the ground towards it, its efforts are doomed to failure: the floor will win out every time.<\/p>

Likewise, the device you\u2019re reading this on is currently exerting a gravitational pull on the planet Neptune, and vice versa.<\/p>

It\u2019s just that your phone or tablet is tiny, Neptune\u2019s huge, and the two are about 4.5 billion kilometres apart, so none of it does either of them any good.<\/p>

Gravity, space and the entire Universe<\/strong><\/h2>
\"An
An image of a protoplanetary disc around star HL Tauri. The dark rings could indicate newly-forming planets in orbit, pushing aside dust as they go. Credit: ALMA (ESO\/NAOJ\/NRAO)<\/figcaption><\/figure>

Out in space, the interaction of all these opposing gravitational forces has given the Universe its structure.<\/p>

A newborn star, for instance, exerts a gravitational force on surrounding matter, such as the protoplanetary disc of dust and gas surrounding it.<\/p>

The young star pulls this matter inwards until said force is matched by that coming from other objects elsewhere.<\/p>

Particles of matter will then go into orbit around the star at this neutral point\u2026 only for gravity to cause them to collide with other particles to form larger ones, and before you know it, you\u2019ve got a bunch of planets on your hands.<\/p>

So yes, there\u2019s gravity in space.<\/p>

You might not think it when, for instance, you see astronauts floating around during a spacewalk.<\/p>

But it\u2019s definitely there \u2013 and be glad it is, because if there was no gravity, we wouldn\u2019t be here!<\/p> <\/body><\/html>\n

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