There’s no north or anything, are there coordinates or you just point at a planet and go for it?
In: Physics
You point your space ship at where the planet will be at your estimated time of arrival. If you aim at the planet, it wont be there when you arrive.
I’ll just address how it’s currently done, not future tech like using pulsars.
The orbit of the Earth around the sun defines “north and south”. This is called the plane of the ecliptic. If you’re above that plane (aka positive direction using the right hand rule), that’s north. To fully locate yourself with three coordinates in 3D space, we also define an arbitrary star (Aries) to be the “starting point” along the rotation of the Earth’s orbit.
There are two aspects to navigating space:
1) Where is my spacecraft pointing?
2) Where is my spacecraft located?
The most popular method to determine pointing is a “star tracker”. Constellations of stars are (relatively) static in the sky. If your star tracker takes a picture of the Big Dipper, you know where you’re pointing with respect to the (relatively) fixed background stars.
To determine where you’re located in deep space, we have what are effectively radar antennas on the Earth. These point at a distance spacecraft, broadcast a signal, and wait for an echo. The timing of the echo tells you how far away the spacecraft is, and the frequency shift tells you how fast it’s moving. After multiple echos over time, you can fully locate the spacecraft in 3 dimensions, and then tell it how to maneuver to reach a targeted planet or other location (since it knows where it’s pointing, it can fire thrusters correctly).
The most important thing to realize about navigation in space is that **everything is in motion orbiting something else**. How that fundamentally happens touches on interactions between mass and gravity, through our best abridged understanding of physical reality.
In order to successfully navigate a spacecraft from here to Pluto, you have to be able to describe orbital motions of every single planet in our system to a reasonable degree of accuracy and **be able to predict** where they’re going to be far into the future. That means initial astronomical observation of celestial objects in the way, which took us **centuries**, and lots of computation which we just now have in the last decades of our existence.
There are orbital [equations](https://en.wikipedia.org/wiki/Orbit_equation) that describe [orbits](https://en.wikipedia.org/wiki/Orbital_elements) and interactions between two bodies but for practical purposes it’s most important to know how massive an object is that you might pass and where it’s going to be by the time you do because a **massive object will easily pull a smaller object closer to it**.
Shoot something slowly toward a massive object, and it will get captured and sink into it. Shoot it faster and its angle will get deflected as it’s pulled in, but it won’t sink. Shoot it cleverly at either speed to either side of the center, and you can control where it’ll end up, like a billiard ball.
Our solar system is rotating more or less in a disc shaped path. When the **New Horizons spacecraft** was launched toward Pluto in 2006, it took on a sort of a corkscrewing path out. It was launched at a time when we knew it wouldn’t pass by Mars and thus wouldn’t get sucked into its gravity well.
However, it was purposely aimed to where it will buzz by massive Jupiter. That took roughly a year and passing by it at just the right distance **bent the spacecraft’s path**, shooting it faster toward Pluto. Its new path bypased Saturn’s and Neptune’s gravity wells along the way and arrived roughly nine years later, taking [amazing images of Pluto and its moon Charon](https://www.nasa.gov/image-feature/charon-and-pluto-strikingly-different-worlds).
Of note, the team wasn’t hundred percent sure they aimed it just right because of prior observational limits. Major discoveries were made throughout its journey that impacted how it was steered. Only within the last three to maybe six months were they reasonably sure it would manage to get captured by Pluto’s gravity.
During that flight time, our asteroid catalog grew from knowing about a few hundred thousand to now nearly a **million asteroids** in our system, weighing collectively as much as our moon, and affecting orbital computations. Being able to describe paths of orbiting objects in the way of navigation can’t be stressed enough.
The spacecraft finished its Pluto mission and is now [headed toward the Kuiper belt](http://pluto.jhuapl.edu/multimedia-db/NHHopkinsPoster_letterSize.png). On its way, it imaged a number of just recently discovered asteroids and how many more it will manage depends on its dwindling RTG power supply.
You don’t need to use concepts like north or south to understand relative position of things. There is no north or south in Cartesian coordinates either.
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