There are at least 100 billion galaxies inthe universe according to the data from the Hubble space telescope, but we’re stillso far away from understanding even our own.
While it’s “only” an average-sized galaxy, the Milky Way contains billions of stars and billions more planets, all orbiting a supermassiveblack hole.
But, will we ever get to see all of the armsof this spectacular spiral? This is Unveiled, and today we’re answeringthe extraordinary question; how long would it take to travel the Milky Way? Are you a fiend for facts? Are you constantly curious? Then why not subscribe to Unveiled for moreclips like this one? And ring the bell for more fascinating content! Since all objects in space are moving allthe time, we’re actually traveling across the Milky Way right now.
Earth may be orbiting the sun at 67, 000 milesper hour, but the solar system is orbiting the galactic center at an even more mindbogglingspeed of 500, 000 miles per hour.
At this speed, it takes us roughly 230 millionyears to complete a full lap of our spiral galaxy, which is otherwise known as a “cosmicyear”.
It takes so long that the Earth, being approximately4.
5 billion years old, has only completed nineteen (possibly twenty) full circuits ofthe Milky Way in its history.
And since our planet is already halfway throughits expected lifespan, it’s only got time left to do the same number again.
The Milky Way has a diameter of at least 105, 000lightyears.
Since a lightyear is 5.
88 trillion miles inlength, this makes the Milky Way more than 600 quadrillion miles from one end to theother, though this is actually a conservative estimate.
Other studies have suggested that the MilkyWay’s disk might reach as far as 200, 000 lightyears, as stars orbiting the galacticcenter have been found much further out than we previously believed was possible.
This means that it would take a photon travelingat the speed of light up to 200, 000 years to cross the Milky Way, depending on whereyou draw the boundary.
Humans, though, unlike photons, can’t travelat the speed of light.
And, even if we could, while 200, 000 yearsisn’t all that much in the general history of space, it certainly is for us; modern humansonly evolved between 200, 000 and 300, 000 years ago, so by the time you’d have completedyour impossible-but-hypothetical circuit of the Milky Way at lightspeed, you’d stillhave been gone for as long as it previously took the humans you left behind to evolveinto themselves.
By the time you returned, if humans were stillliving on Earth then they could well be totally unrecognizable to you.
But, seeing as humans can’t travel (andlikely never will be able to travel) at the speed of light, what are our options if wewere to set off on this journey today? Well, the most common mode of transport onEarth is cars, with now more than a billion cars on roads all across the planet.
Obviously, cars as they are don’t fly; butsay they could.
If you drove one at a leisurely, consistentspeed of sixty miles per hour, it would take you two trillion years to cross the MilkyWay galaxy.
It’s lucky, then, that we have some muchfaster vehicles at our disposal for space travel.
The Voyager space probes travel through spaceat around 35, 000 miles per hour, a much more impressive rate which would reduce our journeytime, but still only to about two billion years.
So, could we do even better? Well, the Juno space probe reached 165, 000miles per hour at its peak, in 2016… the catch being that Juno could only get to thisvelocity while it was also being pulled in by the gravity of Jupiter.
But, if we could somehow maintain this speed, then crossing the galaxy should now take roughly 400 million years, only.
And then there’s the Parker Solar Probe, NASAs ground-breaking mission to the sun, which it’s thought could tip 430, 000 milesper hour by the time its journey is complete – an incredible speed which, if it were possibleto maintain, would ask of us a mere 150 million years to complete our trip.
A considerably more efficient commute thanour hypothetically flying car! Practically speaking, though, there are plentyof problems with using speeds achieved by space probes for this particular thought experiment;not least that space probes aren’t anywhere near big or safe enough to house humans…which somewhat limits the methods we can even feasibly use for long-haul space travel.
So, how do we get around it? Generation ships are currently seen as oneof our best options for seeing the entirety of the Milky Way up close.
A huge ark capable of sustaining thousandsof people could theoretically drift through the galaxy with the aim of exploring and cataloguingeverything in it.
Generation ships don’t shy away from theissue of humans living short lives, either, instead operating on the fact everybody onboard will grow old and die.
Many generations would come and go withoutever seeing a new planet or star, but they’d still have a better chance of doing so thananyone left behind on Earth.
With every mile they moved away from Earth, they’d be a mile further into totally uncharted territory! But again, the extremely gradual journey wouldalso take far longer than the time humans have already been alive for – so there’sno telling how our species will’ve changed after centuries spent cooped up inside thesame spaceship.
By the time they reached their destinationthey and the humans they had left behind on Earth could even have taken totally differentevolutionary paths, becoming unrecognisable to each other were they to one day somehowmeet.
Going one step even further, those on boardthe generation ship and those left on Earth might even have forgotten about each otherover time; so, if there ever was a meeting, neither side would know the significance ofit.
But, maybe there’s another way – a wayfor the same people as started the journey to see the Milky Way without leaving it inthe hands of their descendants thousands of years down the line.
As a sci-fi favourite, putting humans “intohibernation” is probably one of the most popular suggestions for how we could makesure astronauts survive long journeys.
In the real world, it has been proposed forall sorts of missions, be it comparatively short trips to Mars or genuine deep spacetravel much further afield.
In theory, hypersleep (or suspended animation)would mean that Earth could send a smaller crew in a smaller and faster vehicle thana gargantuan generation ship, only waking them up from hibernation precisely when therewas actually something interesting to look at.
Unfortunately, hypersleep is much more sciencefiction than science fact at the moment, but that doesn’t mean we aren’t trying tocome up with solutions like it.
Exactly how any crew on board would decidewhat was and wasn’t worthy of stopping of for would be another problem entirely.
On a journey across the Milky way we would, after all, have an entire galaxy’s worth of stuff to consider.
Would we want to stop and examine every singleplanet, every alien solar system, every black hole? Even forgetting the mammoth transit timesit would take to get to anywhere else for a moment, the Milky Way contains at least100 billion planets.
If you were to spend a day on every singleone, that’s 100 billion days – which is over 250 million years in itself.
Shave that figure down so that we only payvisit to potentially habitable, possibly Earth-like planets, and the number is still huge… withat least 11 billion but perhaps more than 40 billion qualifying worlds out there, sothat’s a minimum of 30 million years.
Humans live for 72 years on average, and theaverage age of an astronaut candidate before training in the US is 34.
If every astronaut worked until they died, they might enjoy an average of around 35 years in which to explore, or 12, 775 days.
In a hypothetical time when visiting a planet(or moon, or any other kind of object) a day was possible (which, obviously, it very definitelyisn’t right now), that means just 12, 775 pitstops per human lifetime… Which is barely scratching even the surfaceof the surface when it comes to the Milky Way! Ultimately, even traveling as fast as it’sphysically possible for matter to go, this particular journey would still take up to200, 000 years to complete.
It would take far longer than a single humanlifespan even if you were moving at ten times the speed of light! So, maybe the best way of exploring our galaxyin its full and fantastic entirety really is by simply looking into the night sky… Because that’s how long it takes to travelthe Milky Way.
What do you think? Is there anything we missed? Let us know in the comments, check out theseother clips from Unveiled, and make sure you subscribe and ring the bell for our latestcontent.