What's outside our solar system?

Where does the solar system end? (ABC, Australia)
Where in the universe is Voyager? The surprising showdown over where our solar system ends (TIME)
What defines the boundary of the solar system? (NASA)
Live tracking: Where are the Voyager probes now? (NASA)
Voyager 1 is travelling at ~17 km/second (Wikipedia)
It's believed that Voyager 1 is either in interstellar space or pretty close to it (the heliopause) - that's the furthest we've sent anything (Wikipedia)
In about 30,000 years, Voyager 1 will have passed through the Oort Cloud & in 40,000 years it will pass within 1.6 light-years of the star Gliese 445 (Wikipedia)
The infamous 'pale blue dot': Earth as seen by Voyager 1 from 6 billion km (Wikipedia)
What is the heliopause? (Encyclopaedia Britannica)
What is the heliopause? (Southwest Research Institute)
The heliosphere: A proper sciencey paper (Max-Planck-Institut für Aeronomie)
What is the Kuiper Belt? A belt of icy bodies beyond Neptune (Cosmos, Swinburne University)
What is the Oort Cloud? A hypothesised belt of icy bodies in the far reaches of the solar system (Cosmos, Swinburne University)
Voyager 1 & 2 spacecraft flight paths (The Planets Today, Vimeo)
Could the Voyager, Pioneer & New Horizons probes eventually be caught by the gravity of another star & start orbiting that star? (Quora)
What is a galaxy? (NASA)
Galaxies & how they're formed (NASA)
The Milky Way galaxy (NASA)
Hubble’s high-definition panoramic view of the Andromeda galaxy (NASA)
All about the Andromeda galaxy (EarthSky)
Elliptical galaxy facts & definition (Space.com)
Spiral galaxy facts & definition (Space.com)
Estimates on how many solar systems & galaxies there might be in the universe (University of Cambridge)
How many solar systems are in our galaxy? (NASA)
Do all stars have solar systems? (Dept. of Physics, University of Illinois)
How did our solar system form? (HubbleSite)
Are we really all made of stardust? Yep (Phys.org)
How are stars formed? (Science, How Stuff Works)
Population I stars (younger) tend to be in the discs of spiral galaxies & made of heavier elements (Hyperphysics, Georgia State University)
Population II stars (older) tend to be in globular clusters & the nucleus of galaxies & made of lighter elements (Hyperphysics, Georgia State University)
Main sequence stars on the Hertzsprung-Russell diagram (Hyperphysics, Georgia State University)
Interactive Hertzsprung-Russell diagram (Las Cumbres Observatory)
Black holes come in 3 varieties: Stellar, supermassive & intermediate (Space.com)
Into a black hole: A lecture transcript from Prof. Hawking (Stephen Hawking)
Journey into a black hole (HubbleSite)
The escape velocity for Earth is ~25,000 miles/hour or 40,000 km/hour (Wolfram Alpha)
A list of escape velocities for the planets, moons, sun & solar system (Wikipedia)
A list of the gravity values for all the planets compared with Earth (NASA)
Definition of massive: "Having relatively high mass" (The Free Dictionary)
How do black holes work? (Science, How Stuff Works)
Black hole jets can influence star formation in galaxies by dispersing & heating interstellar gas (Phys.org)
What happens when 2 black holes collide? You get gravitational waves like the one LIGO detected in 2015 (LIGO)
Exoplanets are planets outside our solar system (Space.com)
How long does it take for a star to ignite at birth? Not long, but the first photons of light may not escape for thousands of years (Reddit)
First sun, then planets: The formation & evolution of the solar system (Wikipedia)
Solar system formation (Windows 2 the Universe)
What's the difference between comets & asteroids? (EarthSky)
What is an orbit? (NASA)
A list of solar system objects by orbit (Wikipedia)
There are >8,000 artifical objects orbiting Earth (National Geographic)
How can one say that gravity is a very weak force, when all the planets & stars are rotating around due to gravit