<p><strong>note:</strong> 180,000 mph is about 290,000 kph is about 80.5 km/sec.</p>
<blockquote>
<p>Why can't we leave in a direction opposite our system's movement to achieve deepspace flight?</p>
</blockquote>
<p>A spacecraft will start out deep in Earth orbit, moving at 8 km/sec <em>relative to Earth</em>.</p>
<p>If it burns a lot of fuel, it can raise its orbit (which actually lowers it's velocity relative to Earth) and eventually escape Earth's gravity into a deep heliocentric orbit (at 1 AU) with a very low velocity relative to Earth, but a 29.8 km/sec velocity <em>with respect to the Sun</em>.</p>
<p>If it burns a lot of fuel <em>again</em>, it can raise its orbit (which actually lowers it's velocity relative to the Sun) and eventually escape the Sun's gravity into a deep <em>galactocentric</em> orbit (at 1 26,000 lightyears, 1,600,000,000 AU) with a very low velocity relative to the Milky Way galaxy, but a 200 km/sec velocity <em>with respect to the center of the galaxy</em> because that's how fast the Sun moves in its orbit.</p>
<p>In all propulsion designs that have been well demonstrated in interplanetary missions to date, there's really no way to have more fuel left to do much more acceleration.</p>
<p><strong>bottom line:</strong> While &quot;breaking free&quot; of Earth's and then the Sun's gravities, you end up far away from them, but with almost zero velocity with respect to them.</p>
<p>However you then end up moving with nearly their same speed with respect to the next bigger gravitational body.</p>
<p>And it doesn't really matter which direction you go.</p>
<p>The Voyager spacecraft are pretty much in interstellar space now. They have velocities of about 15 and 17 km/sec relative to the Sun, but both have roughly more-or-less the Sun's 220 km/sec velocity relative to the center of the galaxy.</p>
<p><strong>note:</strong> All speeds are approximate, and from memory or from googling. They are for illustrative purposes only; the nature of the answer doesn't depend on the accuracy of the example velocities given.</p>
<hr />
<p>This inelegant plot shows the speeds and distances of Voyager 1 and Voyager 2. They went in somewhat different directions (but not opposite) with one going up, out of the ecliptic, but the speed differences primarily due to a different number of gravitational boots at various planets, not the directions.</p>
<p><a href="https://i.sstatic.net/RTIZp.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/RTIZp.png" alt="Voyager 1 and 2 speed and distance from (15 December 2018) Data source: HORIZONS System, JPL, NASA" /></a></p>
<p>Image source: <a href="https://commons.wikimedia.org/wiki/File:Voyager_speed_and_distance_from_Sun.svg" rel="nofollow noreferrer">Voyager 1 and 2 speed and distance from (15 December 2018) Data source: HORIZONS System, JPL, NASA</a></p>
<hr />
<p>From the Space SE question <a href="https://space.stackexchange.com/q/41808/12102">Why was Canberra able to listen to Voyager 2 but not talk to it?</a>:</p>
<blockquote>
<p>From <a href="https://space.stackexchange.com/a/20932/12102">this answer to <em>Voyager Earth to Jupiter journey time</em></a>:</p>
</blockquote>
<blockquote>
<blockquote>
<p><strong>below:</strong> data for the Sun, planets, Pluto, Voyager 1 and Voyager 2, from January 1, 1969 (a good year to start things) until now. Dots are now. Data is from <a href="http://ssd.jpl.nasa.gov/horizons.cgi" rel="nofollow noreferrer">NASA JPL Horizons</a>. Reposted from <a href="https://space.stackexchange.com/q/14317/12102">How well can Voyager 1 separate Earth signals from Solar noise these days?</a>, where additional details are given.</p>
<p><a href="https://i.sstatic.net/fp1gO.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/fp1gO.gif" alt="enter image description here" /></a></p>
</blockquote>
</blockquote>

CC BY-SA 4.0
2023-05-12T21:48:35.157Z
2023-05-12T21:48:35.157Z
uhoh
<p>Assuming our entire system (stars, planets, etc) is moving through space at around 180,000 mph. Why can't we leave in a direction opposite our system's movement to achieve deepspace flight?</p>
<blockquote>
<p>Part two</p>
</blockquote>
<p>What, if any is the force needed to break the pull within the solar system?</p>

CC BY-SA 4.0
2023-05-05T08:13:34.440Z
Your question is rather confusing. There's only one star in the solar system: the Sun. Why would travelling in the opposite direction to the solar system's motion (relative to the neighbouring stars) be useful? No matter which direction you go, momentum is conserved.
PM 2Ring
CC BY-SA 4.0
2023-05-05T09:46:41.707Z
You can leave the Solar System in any direction you want. It's marginally easier to escape if you go toward or away from the Galactic Center, due to tidal forces -- but this is a minuscule consideration.
Sten
CC BY-SA 4.0
2023-05-07T01:04:13.497Z
Leaving in the opposite direction of the solar system's movement doesn't really make travel quicker. Even though you leave earth, you are already in motion along with the solar system, despite leaving the earth behind.
Greg Burghardt
CC BY-SA 4.0
2023-05-12T15:29:45.017Z
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Community
<space-time><speed><escape-velocity>
Space travel relative to solar system's movement through space
James Long
# Space travel relative to solar system's movement through space

(Asked by: username_0 on 2023-05-05)

Assuming our entire system (stars, planets, etc) is moving through space at around 180,000 mph. Why can't we leave in a direction opposite our system's movement to achieve deepspace flight?

> Part two

What, if any is the force needed to break the pull within the solar system?

**Tags:** space-time, speed, escape-velocity

> **Comments:**
> **username_1**: Your question is rather confusing. There's only one star in the solar system: the Sun. Why would travelling in the opposite direction to the solar system's motion (relative to the neighbouring stars) be useful? No matter which direction you go, momentum is conserved.  
> **username_2**: You can leave the Solar System in any direction you want. It's marginally easier to escape if you go toward or away from the Galactic Center, due to tidal forces -- but this is a minuscule consideration.  
> **username_3**: Leaving in the opposite direction of the solar system's movement doesn't really make travel quicker. Even though you leave earth, you are already in motion along with the solar system, despite leaving the earth behind.  
> **username_4**: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.  

---

## 1 answers

### Answer by username_5 on 2023-05-12. Score: 1

**note:** 180,000 mph is about 290,000 kph is about 80.5 km/sec.

> Why can't we leave in a direction opposite our system's movement to achieve deepspace flight?

A spacecraft will start out deep in Earth orbit, moving at 8 km/sec *relative to Earth*.

If it burns a lot of fuel, it can raise its orbit (which actually lowers it's velocity relative to Earth) and eventually escape Earth's gravity into a deep heliocentric orbit (at 1 AU) with a very low velocity relative to Earth, but a 29.8 km/sec velocity *with respect to the Sun*.

If it burns a lot of fuel *again*, it can raise its orbit (which actually lowers it's velocity relative to the Sun) and eventually escape the Sun's gravity into a deep *galactocentric* orbit (at 1 26,000 lightyears, 1,600,000,000 AU) with a very low velocity relative to the Milky Way galaxy, but a 200 km/sec velocity *with respect to the center of the galaxy* because that's how fast the Sun moves in its orbit.

In all propulsion designs that have been well demonstrated in interplanetary missions to date, there's really no way to have more fuel left to do much more acceleration.

**bottom line:** While "breaking free" of Earth's and then the Sun's gravities, you end up far away from them, but with almost zero velocity with respect to them.

However you then end up moving with nearly their same speed with respect to the next bigger gravitational body.

And it doesn't really matter which direction you go.

The Voyager spacecraft are pretty much in interstellar space now. They have velocities of about 15 and 17 km/sec relative to the Sun, but both have roughly more-or-less the Sun's 220 km/sec velocity relative to the center of the galaxy.

**note:** All speeds are approximate, and from memory or from googling. They are for illustrative purposes only; the nature of the answer doesn't depend on the accuracy of the example velocities given.

---

This inelegant plot shows the speeds and distances of Voyager 1 and Voyager 2. They went in somewhat different directions (but not opposite) with one going up, out of the ecliptic, but the speed differences primarily due to a different number of gravitational boots at various planets, not the directions.

[![Voyager 1 and 2 speed and distance from (15 December 2018) Data source: HORIZONS System, JPL, NASA](https://i.sstatic.net/RTIZp.png)](https://i.sstatic.net/RTIZp.png)

Image source: [Voyager 1 and 2 speed and distance from (15 December 2018) Data source: HORIZONS System, JPL, NASA](https://commons.wikimedia.org/wiki/File:Voyager_speed_and_distance_from_Sun.svg)

---

From the Space SE question [Why was Canberra able to listen to Voyager 2 but not talk to it?](https://space.stackexchange.com/q/41808/12102):

> From [this answer to *Voyager Earth to Jupiter journey time*](https://space.stackexchange.com/a/20932/12102):

> > **below:** data for the Sun, planets, Pluto, Voyager 1 and Voyager 2, from January 1, 1969 (a good year to start things) until now. Dots are now. Data is from [NASA JPL Horizons](http://ssd.jpl.nasa.gov/horizons.cgi). Reposted from [How well can Voyager 1 separate Earth signals from Solar noise these days?](https://space.stackexchange.com/q/14317/12102), where additional details are given.
> >
> > [![enter image description here](https://i.sstatic.net/fp1gO.gif)](https://i.sstatic.net/fp1gO.gif)


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