How does Jupiter make space things go faster? (or, What's a Gravity Assist?)

New Horizons flew past Jupiter on February 28th, 2007, for a little speed boost on its way out to Pluto. But how did Jupiter's gravity translate into more speed for the probe? Hint: It's all about momentum.

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Written, Directed, Filmed, Edited and Animated by Tech Adams.
© 2015, Tech Adams Laboratories

New Horizons animations courtesy of NASA.

Jupiter Family of Rockets - by Kraisee, modified from the work of Ross B Tierney. Public Domain via Wikimedia Commons

Milky Way Galaxy - Artists Conception by Nick Risinger. Public Domain via Wikimedia Commons

[thomasrichardson]

First video to break down the math to the separate vectors, where the answer lies. You sir hit the nail right on the head with this one. Congratulations

[miguelcarvalhoaraujo]

Thanks for clarifying that gravity assist only works if the planet is moving!! This has puzzled me for a long time because, as you also explained, if the planet wasn't moving there would not be any change in speed. Most videos only show what gravity assist is but not actually explain how the probes can increase their speed. Great video and clear explanation. Many thanks!

[Mehwhatevr]

this is one of those things that I knew, but I was having trouble understanding. I've watched a couple videos and yours is the only one that really explained it. Just wanted you to know :)

I guess what makes this hard to understand, is that it's hard to visualize it happening with a moving Jupiter. Everytime I try to visualize it it's with a stationary Jupiter. I would like to see this done with a moving gravity well experiment. one of those funnels that you drop a ball into.
It's still difficult to try and visualize this without getting confused. but your explanation is the first that has given me something to sink my teeth in. I struggle with the, even though it's falling in and out of a moving well, my visual processes want to say that that movement would be added and subtracted. lol. that it would pick up the lateral speed of the planet but the planet would still pull back on it as it leaves. Like the probe's inertia would resist the pull of Jupiter. ugh...

edit: oh I see in your illustration now that the probe never moves to the left of Jupiter. Therefore Jupiter can only ever pull it in one direction. If the probe had tried to leave to the left of Jupiter, perhaps Jupiter might have pulled it back and canceled out some or all of the boost. So even has the probe is leaving the gravity well, it's only ever being pulled in "one" direction. by jupiter.

[JasonWilliams]

1:23 This has confused me for so long LMAO. Thanks for clearing it up.

[TerryClarkAccordioncrazy]

Thank you, I finally understand something that had puzzled me for longer than I want to admit.

[niceprofile-ki]

Thanks for actually getting into the explanation

[bharat]

thanks, you explained it in a very simple way, helped me to understand quickly

[keifer]

awesome! well explained! exactly what I was here to learn

[ahriman]

New Horizons actually did have enough speed after launch to reach Pluto. Jupiter flyby only sheared off 5 years from the voyage time.
The Engineers even took it into equation that if they missed a month long launch window and were unable to take advantage of Jupiter anymore, it would still reach Pluto.

[expired]

I have watched a number of videos on gravity assists trying to understand the concept properly.
Your video is very well put. I actually understand now!
thank you

[breadgonebad]

God, I have been asking myself this question for so long, and haven't felt like anyone explained it like you did. Excellent video. Can't believe I was today years old when I realised how gravity assists work :/

[itchibahn]

Excellent video. Had to show it to my 8 and 10 year old kids.

[brucepenich]

thank you for the explanation. i had watched another video and it did not explain it sufficiently for me to understand it.

[NEMAS]

these videos are great! gonna share them with all my friends!

[GiovanniApreaCapri]

YOu're good at it and you add that tiny bit of fun to the whole story and, last but no least, your speech pace makes so that even a non English one like me can get it (almost) all, bravo!

[kaivalyashenoy]

Thank you, helped a lot in understanding gravity assist.

[jameswalley]

Thanks ... You have just answered one of my brain stopping questions on how a probe can be accelerated by doing a planet fly-by.

[yesinsky]

holy shit you explained this sooo good, my physics textbook didnt go into enough detail and was just plain confusing, but this made it so clear and easy to understand! great job

[Hans-ChristianSchwartz]

after wading through non explaining gravity assist videos, i'm glad I found this :D

[rwired]

Your animations are so neat and polished! Great stuff. Do they take a long time to make? If you don't mind me asking... what software are you using?