What is the Speed of Gravity?

We often hear the phrase, faster than the speed of light, thanks to Queen, no doubt.

Our old science lessons in school way back when and pop lyrics allow us to remember how fast light travels, saving us shame on a pub quiz.

But what about gravity? In every part of our lives, it is keeping our feet firmly on the ground and apples falling on our heads, but what do we know about gravity’s speed?

Just how fast is gravity?

Not knowing can leave us red-faced, shamed, and, let’s face it, disgracing our education.

A wrong answer on the quiz can leave us excluded from next week’s semi-finals or with a big old F on our homework; it’s a sight none of us want!

Whether it’s for science homework, a quiz, or plain curiosity, knowing the speed of gravity is a fact that alludes so many of us.

So today, let’s put it to rest and find out: what is the speed of gravity?

What is gravity?

Before we get into it, let’s just have a quick refresh for our rusty science minds.

Gravity is an invisible force that pulls objects towards one another. It is the force that keeps our feet on the ground and is responsible for items falling to the ground if you let them go.

Anything that has mass will have gravity. Objects with more mass (are heavier) will have more gravity and a stronger gravitational pull.

It means that these items will fall to the ground quicker than others. Consider how you see a feather floating for ages before it falls to the ground, whereas a piano would drop pretty quickly.

The amount of mass in relation to gravity is an essential factor to remember as we move on to the speed of gravity.

What is the speed of gravity?

The speed of gravity on Earth is about 9.8 meters per second. We measure this by calculating the acceleration given to freely falling objects.

The objects falling will see their speed increasing by roughly 9.8 meters (or 32 feet) per second that it falls.

Those items we mentioned earlier with a larger mass will accelerate quicker due to a larger amount of gravitational force pulling them down.

As we saw earlier, the speed of gravity, or how quickly an object falls to the ground, is dependent on a few factors, which means no one answer suits all to the speed of gravity.

Is there a maximum speed of gravity?

As we have already seen, gravity is keen to pull you back down to Earth. For example, if you jump, the higher you jump, the more it can hurt your feet or knees as you land thanks to gravity pulling you down.

But is there a maximum speed that gravity can travel? Well, there is! The maximum speed is known as terminal velocity. Similar to what we have already seen, terminal velocity is determined by a few factors. Mainly the weight of an object, it’s surface area, and what it's falling through.

Let's Take the feather again. It is lightweight and has a large surface area that the air sees, which gives it a slower terminal velocity speed than, say, a rock with the same weight.

When it comes to sky diving or objects falling through the sky, their speed can be impacted by any opposition winds or drag. The fastest skydiving speed is currently 988 km/h!

The impressive speed was achieved by orienting his body and jumping at a high altitude where there was less wind resistance.

In the free-fall position, the fastest terminal velocity achieved is about 195km/h! You can increase the terminal velocity by orienting your head towards the Earth, increasing your velocity to over 400 km/h!

It is worth remembering the impacting environmental factors that can change the terminal velocity speed of gravity!

What about other planets?

You may be wondering, what about the moon? Or Mars? When we have seen videos of people walking on the moon, they are floating, jumping across the surface differently from how we walk on Earth.

The difference is the gravity levels. On the moon, gravity acts at a different speed, taking longer to pull you down to the ground.

The gravitational speed on the moon is about 1.8 meters per second; that’s quite a difference from what we see here on Earth!

What about in space?

Contrary to popular belief, there is some gravity in space! We call this microgravity and allows people and objects to appear weightless.

An excellent example of this is the astronauts we see in space and their things floating around at the International Space Station.

Microgravity means a tiny amount of gravity still exists. It allows large objects to be moved around easily but does have an impact on the body.

As things seem to weigh less and a weaker force pulls you to the ground, your muscles and bones can become weaker as they don’t need to work as hard.

It’s why astronauts will have muscle stimulation machines onboard a space station to ensure they don’t deteriorate too much. We can also replicate microgravity on Earth. NASA does this when preparing astronauts for microgravity.

They will use an airplane and fly it up-and-down in parabolas. At the top, people and objects inside the plane will free fall for roughly 20-30 seconds, thus experiencing microgravity.

You can also briefly experience microgravity on roller coasters or free-fall rides at amusement parks!

How does it compare to the speed of light?

Some scientists argue that the speed of light and the speed of gravity must be equal. All the planets in our solar system are held in place by gravity or gravitational force. It is the pull from the sun that we all orbit around, so what if that stopped?

Scientists argue that if the sun stopped emitting light, it would take us on Earth roughly 8 minutes to notice due to the speed of light traveling from the sun (This would make the speed of gravity consistent with the speed of light 299,792,458 m/s).

There have been debates and countless experiments over the years regarding the speed of gravity and light.

Many scientists are now concluding that the speed of gravity and the speed of light will differ no more than 1 part in a quadrillion. It works out at 10 to the power of 15.

Final Word

And here we are, the end of the line. As you can see, there are a few factors that can impact the speed of gravity.

The mass of an object will dictate its gravitational mass and how quickly it will fall to the ground.

The speed of gravity will differ from planet to planet, giving us slightly different readings and times. What is clear to us is that gravity works pretty quickly!

The invisible force not only keeps our feet firmly on the ground, but our planet and moon hang in perfect balance, rotating around the sun, keeping us warm and not floating into deep space!

Gordon Watts
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