# Speed

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#### unseen

##### Guest
So once we get out of earth gravity we travel @ 17,000 MPH or something like that I forgot the exact number??? but what i was wondering does nayone know how fast we would travel outside the solar system away from the sun's gravity? and then what about outside the galaxy away from the black holes gravity??? also then are you always pulled by something is there a spot anywhere say once we get outsid ethe local group is there a place where something is not pulling you in ? Babble Babble...anyway thx for a responce ahead of time. <div class="Discussion_UserSignature"> </div>

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#### SpeedFreek

##### Guest
The escape velocity from Earth is 11.2 km/s or around 25,000 mph.<br /><br />As to how fast we would travel when in interstellar space, well that is up to us, and how much delta-vee we can get from gravitational sling-shots around other planets on our way out, or from our thrusters/light-sail/ion drive/other methods of propulsion.<br /><br />To put it into context, Voyager 1 was launched in 1977 and has reached 100 AU from the sun. It is currently travelling at around 17.1 km/s (38,000 mph) and it has gained most of this speed from getting gravitational boosts from the planets it visited on its journey. It is reckoned that it will be another 10-20 years before Voyager 1 is outside the suns influence (once it has passed the <i> heliopause). </i><br /><br />I'm not sure how to answer the rest of your questions! <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### willpittenger

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I think you missed the question. I read the question as being "How fast to you have to go to prevent your trajectory from eventually, causing you to fall back towards the Sun (or at least Inner Solar system)." That would be escape velocity. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

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#### SpeedFreek

##### Guest
I didn't exactly miss the point, it's just not a simple question to answer. It depends on where you start and what route you take.<br /><br />For instance, Voyager 1 is not predicted to eventually fall back towards the sun. So it has reached the escape velocity of our solar system and is travelling at 17.1 km/s.<br /><br />But it all depends how you do it. If you are on mercury, and starting from a resting state, the escape velocity from the suns gravity is 67.7 km/s. If you are starting from Saturn it is 13.6 km/s. From Pluto it is 6.7 km/s.<br /><br />So it all depends where you start from, and what boosts you get on the way.<br /><br /> This link will explain what I meant. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### nexium

##### Guest
We need to consider relative to what. I presume that 6.7 kilometers per second is relative to Pluto not Earth at the Equator.<br />The 17000 miles per hour is the correct speed for a circular, equitorial orbit around Earth at about an altitude of 1000 miles; a bit faster for a bit closer to Earth's surface. If you are 6 trillion miles from Earth = one light year, with zero speed with respect to a spot on the Equator of Earth, your speed and direction will change daily due to Earth's rotation and very slowly due to the very weak gravity gradiant. You are in a highly eliptical orbit around the galaxy, but you are not likely to hit anything bigger than a pea in the next million years. Neil

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#### qso1

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That may not have a clear cut answer. I have a figure for solar escape velocity which IIRC was over a million mph. No spacecraft of ours has gone that fast which IMO, leaves open the question...will the Pioneers and Voyagers really escape the suns gravitational influence?<br /><br />Much of the reporting about Voyager escaping the suns gravity may have been based on NASA officials not thinking through the scenario or...at some point, you get so far out that it takes little momentum to actually slowly slide free from the suns influence.<br /><br />I will try to find the solar escape velocity figure and source and post it here. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

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#### qso1

##### Guest
A lot of space exists outside the local group and other galactic clusters that I'd have to say yes...there is a place where there would be no direct influence on anything in that spot. AFAIK, the Universe has no known singular source of gravity to pull you in. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

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#### qso1

##### Guest
Found the data I was looking for, note the escape velocity.<br /><br />Orbital velocity around Galactic center:<br />4,809,413 MPH (7,740,000 KPH).<br /><br />Escape velocity:<br />1,381,308 MPH (2,223,000 KPH).<br /><br />Distance from galactic center:<br />32,000 Ly.<br /><br />Estimated orbital period:<br />225 million years.<br /><br />Data source:<br />"THE NEW ATLAS OF THE UNIVERSE". <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

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#### SpeedFreek

##### Guest
But qso1, that is only the escape velocity if you start from the surface of the Sun!?! It is 617 km/s (or 2,223,000 km/h), as shown in the link I posted above.<br /><br />But if you start from the surface of Mercury you need 4.4 km/s to escape from Mercury and 67.7 km/s to escape from the Suns gravity.<br /><br />From Earth, you need 11.2 km/s to escape the Earths gravity and 42.1 km/s to escape from the Suns gravity.<br /><br />From Plutos orbit, you need 6.7 km/s to escape the Suns gravity. Voyager 1 is currently outside Plutos orbit and is travelling at 17.1 km/s, relative to the Sun.<br /><br />So Voyager will easily escape the Solar System!<br /><br />Don't forget, the pull of gravity gets less, the further you are from the source! <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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