When we talk about space, often we focus on the Solar System, or other stars or galaxies.
We also view the space between stars as empty, but it is anything but empty.
At the very edge of our Solar System, there is a place where interstellar, the space between stars, begins and the influence of the Sun stops.
Voyager 1 and Voyager 2 crossed this boundary in 2012 and 2018 respectively, and are now out there in interstellar space.
So what kinds of things might they eventually go past or run into?
Astronomers refer to the "stuff between stars" as the "interstellar medium" or ISM.
There is a lot to study between stars, usually many different kinds of clouds of dust and gas.
These can be giant clouds that will eventually go on to form stars, sometimes called "stellar nurseries" where hundreds of stars are all growing and forming.
As these baby stars grow, they heat up the cloud around them, changing the way the cloud appears and behaves.
Sometimes the stars will light up the area around them, and the cloud will reflect all of this light.
Sometimes the stars will heat up the cloud around them, causing the cloud to emit its own light.
And sometimes as the stars light up and heat the cloud around them, the make-up of the cloud can change, since not all molecules can survive being very close to stars.
The clouds we see may not always be forming stars though.
The space between stars is also filled with all of the remnants of older generations of stars that have already gone supernova, or have reached the ends of their lives in less violent ways.
The stuff that comes out of these older generations of stars feeds into the clouds that will make the new generations of stars, enriching them with different chemicals that they might not have had otherwise.
This means that different kinds of solar systems can grow around stars, with rocky planets, instead of everything only being gas giants.
Sometimes there can be clouds blocking our view to the stars. Much like what happens on a cloudy night on Earth, there can be clouds in space that make stars harder to see.
This process is called "extinction" or "reddening".
MORE SUNDAY SPACE:
If you think of looking towards the Sun (never look directly at the Sun) on a dusty or smoky day, the Sun will appear redder, and sometimes fainter, because of all the extra particles in the atmosphere.
The exact same process happens when we look through space clouds at stars in space.
Astronomers have to think of ways that they can correct for effect that the space clouds are having on their observations, so they have to understand what is going on between the stars.
So if someone tries to tell you that there is nothing interesting between the stars, think of all the wonderful stages of a stars life, and ask them where they think stars are born.
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