It's the first of
its kind, a habitable planet orbiting a white dwarf- and it doesn't have much longer left
to live.
WD 1054-226 is a 16-magnitude white dwarf that's nearing the end of its life.
Magnitude is the measure of a star's brightness, and is measured both in apparent magnitude-
how bright the star looks to us- and actual magnitude, or how bright the star actually
is at a uniform distance of 10 parsecs, or about 32.6 light years.
White dwarfs tend to be very bright objects, and WD 1054-226 is definitely a bright one!
As a white dwarf, WD 1054-226 is basically at the end of its life.
These stars form from the remnants of suns much like our own that are too small to become
neutron stars or black holes at the end of their lives.
Instead, the star swells up to a red giant and sheds most of its mass, but collapses
back down into a very dense core that no longer undergoes nuclear fusion.
Because a white dwarf is still basically a superheated ball of matter the size of the
earth, and space is a pretty terrible medium by which to transfer heat, white dwarfs can
still shed light and warmth for billions of years, but will survive even longer than that-
practically until the end of the universe itself, though giving off little usable heat
and light for most of that time.
At that point the star will theoretically become a black dwarf- and we say theoretically
because it should take longer than the universe has existed for a star to reach this state,
so no black dwarfs have ever been observed.
The bad news is that habitable planets typically won't survive a white dwarf's previous red
giant phase, as the star swells up to many times its former size and incinerates any
nearby planets.
Any planets far enough away to survive the red giant phase may enjoy a brief period of
habitability as their sun swells in size and pushes out its habitable zone boundary, the
place where water can exist in liquid form, and thus allow for the existence of life as
we know it.
However, red giants typically last around a billion years- which is not much time for
life to get started and evolve.
When a red giant shrinks, those formerly habitable planets will suddenly freeze over, destroying
any life that sprung up during the brief spring the planets enjoyed.
So if planets close enough to be habitable can't survive a red giant phase, imagine scientist's
surprise to discover strong evidence that WD 1054-226 has a habitable planet sitting
smack-dab in the middle of its habitable zone.
The discovery was made by University College London's Professor Jay Farihi and his colleagues,
who recorded changes in light from WD 1054-226 over 18 nights.
What they found were dips in light which corresponded with 65 evenly spaced clouds of planetary
debris which orbit the star every 25 hours, and it was the regularity of the planetary
debris clouds that clued them in to the possibility of a habitable planet orbiting this white
dwarf.
We know from our own solar system that Saturn's moons help it maintain a stable ring structure,
and simulations tell us that without moons set in specific orbits, Saturn's rings would
collapse or be hurled off into space.
Thus in order to keep 65 clouds of debris in such precise, evenly spaced orbit around
WD 1054-226 a planet about the mass of one of our own rocky planets here in the solar
system is believed to be orbiting the white dwarf and shepherding the debris structures
with its own gravity.
This planet is believed to be about 2.5 million kilometers (1.55 million miles) from its sun,
or a shocking 1.7% the distance between Earth and our own sun.
If the Earth orbited the sun at that same distance it would be a hard-boiled chunk of
rock thousands of degrees hot, and the sun would take up the entire horizon when you
looked up into the sky.
But because WD 1054-226 is a white dwarf and much, much cooler than our sun, this is actually
the perfect distance to keep the planet at a nice balmy temperature that allows for liquid
water.
Since here on earth life can't exist without liquid water, finding planets within their
star's habitable zone is our best bet for finding alien life- and the planet around
WD 1054-226 just might host such life right now.
But scientists haven't actually confirmed that such a planet really exists, the data
merely strongly hints at the possibility- because something is keeping those orbital
debris clouds in such precise alignment.
This means that this mystery planet must have formed after WD 1054-226 became a white dwarf,
been an extrasolar capture, or an outer planet that somehow migrated inwards- which is exciting
for the possibility of life as a planet in the current orbit would simply not have survived.
If a planet does exist though, what would life there be like, and how could we reach
it?
Well, when thinking about what life on a planet orbiting WD 1054-226 would be like, it's really
all about the star.
When first becoming a white dwarf, WD 1054-226 would be incredibly hot- so you can forget
about life starting until well after WD 1054-226 lost much of its stored heat.
This alone makes the possibility of life very dubious- but not impossible.
Extremophiles could have evolved even during WD 1054-226's hotter phase, as long as they
liked it hot, and migrated down into the planet's crust until things calmed down up top.
Let's say life had a chance to evolve to the multi cellular phase, and give rise to complex
organisms like animals.
What might that life look like?
Well, being so close to its parent star, our theoretical planet would be tidally locked-
which means one face of the planet would always face the sun and the other would be permanently
dark.
If you're a fan of our Versus series you'll know that we postulated that the Predator's
home planet must have been tidally locked for them to develop their natural infrared
vision- the Yautja likely evolved from predatory animals on the dark side of the planet where
infrared vision would have been a massive advantage while hunting.
Life near WD 1054-226 could possibly evolve the same way, with wildly different evolutionary
paths on both sides of the planet.
On the dark side animals would likely evolve to rely on senses other than sight to hunt
or get around, such as smell.
Some might develop sensory organs that can detect infrared light to help them find prey,
much like many snakes here on earth, only on a larger scale.
When it's permanently dark, you wouldn't have much use for eyes though so just like cave
dwellers here on earth, you could expect to see a lot of blind animals with no pigment.
When you can't see each other, there's no point in evolving pigmented skin.
What you would likely find is that animals are very well insulated, because while the
planet may be in the habitable zone, the side of the planet that's always in the dark is
going to be much, much colder than the day side.
This means either thick fur or large body masses- and we're likely to find some real
giants on this planet thanks to a phenomenon known as polar gigantism.
Due to such low metabolic rates, animals living in really cold conditions like the deep oceans
or the poles tend to grow to be much, much bigger than their warmer-weather cousins.
Mammals would be unlikely here on earth, though if they did evolve they'd have to grow to
be giants much like the ice age ancestors of current animals.
All that extra mass is what allows a mammal to survive extremely cold environments, and
is the reason why polar bears outweigh even grizzly bears by a considerable amount.
Instead of plants, the dark side of the planet could be home to massive forests of fungi-
given that there's enough moisture.
Normal plants simply couldn't survive without sunlight, and we might discover a twilight
world ruled by mushrooms and molds.
Incredibly, fungi here on earth survive in both the Arctic and Antarctic, giving credence
to the possibility of a fungi-based food chain on the dark side of the planet despite the
very low temperatures.
However, finding entire forests of the stuff may be a bit of a stretch- even in Antarctica
fungi is not very widespread.
This limits the possibility of finding large animal life.
In all likelihood, the dark side of the planet would be home to little life, with any that
did exist living in underwater environments close to geothermal vents.
But on the day side of the planet there's hope for more complex and diverse life.
If you were standing on the day side of our hypothetical planet around WD 1054-226, you'd
see the sun as a small orb of light in the horizon- about the size of a large fruit.
What you would immediately notice is that you can actually see the stars even during
high noon.
That's because a white dwarf is much dimmer than our sun, and thus nearby stars would
still be visible during the daytime.
This also means that while you're on the day side, your day would be dimmer than you're
used to, gradually growing dimmer over tens of millions of years.
For life evolving here, the good news is that a white dwarf initially gives off much less
harmful ultraviolet radiation, protecting life from being damaged by solar radiation.
However, this could also be a bad thing as some scientists believe that radiation damage
to DNA can help spur on evolution via helpful mutations.
If you aren't a fan of mushrooms though, then we've got good news for you, because a white
dwarf still gives off light in the right spectrum for photosynthesis to take place.
That means you can have all the normal types of plants, ferns, and trees that you're used
to.
Sort of.
Because a white dwarf is dimmer, these plants would have much darker coloring so they can
absorb more light.
Their leaves would also be bigger so they have a larger surface area to collect light
from.
Narrow-bladed plants such as grass would be improbable here, as they would probably be
too inefficient to survive.
So instead of rolling green hills covered in grass and green trees, you'd probably be
looking at vast fields of very 'fat', wide plants and trees whose leaves are dark gray,
purple, and even black- which might be a little unsettling.
The good news is that in order to attract pollinators- if life evolved down this specific
track- you could probably expect much more vibrant and intense displays from plant life.
This means bigger, brighter flowers, and more aromatic ones too would evolve in order to
catch the attention of interested pollinator animals.
When your whole world is kind of dim and full of dark-colored plant life, there's no room
for subtlety.
Animals here would likely evolve very large eyes to help offset the dim light from their
parent star.
WD 1054-226 isn't dim enough yet for animals to have truly massive eyes though, so you're
basically looking at anime-style animals here (use image: https://i.discogs.com/8g9WYdaSK9K4T82AYZoYg3Y0IBJU-xZcamjcCiy8j1A/rs:fit/g:sm/q:40/h:300/w:300/czM6Ly9kaXNjb2dz/LWltYWdlcy9BLTI0/MTUzNjMtMTMxNjAw/ODk5NC5qcGVn.jpeg),
which might make this the cutest planet in the galaxy.
With a healthy growth of plant life, the day side of the planet wouldn't be as limited
as the night side, and you could expect to find an entire, traditional food web here.
In order to absorb the weak ultraviolet radiation given off by a white dwarf, animals would
have lighter skin tones, so you could expect to run into entire colonies of albinos here.
However, as white dwarfs cool they give off ever-more intense UV radiation, prompting
a shift to darker skin tones until eventually the radiation given off by the sun would become
fatal.
What would be most immediately apparent on the dayside of the planet though would be
a 'bulge' in the planet's atmosphere and oceans if it has them.
Due to the extreme proximity to its star, our hypothetical planet would be near enough
for the suns' gravitational pull to tug on the atmosphere and ocean of the planet, creating
a permanent bulge in the center.
It's lucky then that the planet is tidally locked, because if it weren't a constant massive
wave of water would be washing over the planet with regularity.
Another immediate difference you'd notice is that if you lived on this planet you'd
live to be several hundred years old.
Not because living near a white dwarf can extend your life, but because this planet
is so close to WD 1054-226 that it probably takes only a few weeks to orbit it.
You'd be celebrating a new birthday every few months.
But what if we wanted to find out if life really existed on this possible planet?
Well, the best way would be to simply go there ourselves- and that would be one whopper of
a journey.
WD 1054-226 is about 118 light-years away from us, meaning that with our current rocket
technology it would take us... entirely too long to get there to bother calculating because
human civilization would likely no longer exist by then.
All is not yet lost, and getting to WD 1054-226 within an acceptable timeline is still possible.
Today we actually have multiple means of traveling to nearby stars- or at least the propulsion
technology to do so.
Working out the life support and associated systems is something else entirely, but the
foundations of a near-future spacecraft capable of crossing galactic space are already well
established.
Out of the various methods, the most appealing for both cost and speed is laser propulsion.
This is a propulsion system that doesn't even use an engine, which is great because engines
and the fuel that they need to consume are really heavy and end up dragging a ship down.
When you add fuel to a spacecraft to power its engine, you then need additional fuel
to make sure that your spacecraft can propel the original fuel load to its destination.
Then you need even more fuel to get that fuel to its destination, and so on and so on until
you basically reach infinity- this concept is known as the tyranny of the rocket equation.
However, if you cut out engines and fuel, then you save massive amounts of weight and
thus need less energy to travel faster.
Beamed laser propulsion is the method of propelling a spacecraft through space with nothing more
than the push of photons.
You're constantly being bombarded by photons and they're incapable of moving you even a
single millimeter, but when you're in a frictionless environment like space, and have a really
long time to bombard an object with photons, you can eventually build up some pretty incredible
speed- and making it work is incredibly simple.
First, our spacecraft would have to be as light as possible- though the mass of your
spacecraft is really only limited by the power of your pushing lasers and just how much time
you want to spend getting to where you're going.
Then, you would want to build a nice, large sail which would reflect laser light shined
onto it from great distance- because even laser light diffuses over distance, you want
very large sails to catch as much of it from as far away as possible.
The most important part- the 'engine' of your spacecraft if you will- is the laser emitter
itself, which will shoot a continuous beam of light at your spacecraft for most of the
duration of its journey.
You could build this emitter right here on earth, though it would be limited in efficiency
because it could only beam laser energy at your ship while it was in view.
As the earth rotates the emitter away, you'd have to spend about half a day without receiving
any push from back home, severely limiting the effectiveness of the entire system.
A solution would be to build emitters around the world, to produce a continuous push of
photons on your spacecraft- but a better solution would be to simply build the emitter on a
tidally locked body that's always facing the same direction.
Then your emitter could keep your ship in view at all times, and provide continuous
push for weeks, months, even years.
But you don't want just one emitter, you want dozens of them working together to send concentrated
laser light at your reflective sail.
With this continuous push of laser light, you might barely move at first, but over the
course of a few months you'll already have accelerated to escape velocity from the solar
system.
With a few years of continuous push you'll have reached a healthy percentage of the speed
of light- and the kick is that your maximum top speed is going to be somewhere under the
upper limit of the speed of light.
This makes beamed laser propulsion the absolute fastest way to get around our galaxy.
With distance though laser light becomes ever more diffused and less effective, so at first
beamed laser propulsion will only be good for trips to our closest neighbors.
WD 1054-226 could be well within the reach of beamed laser propulsion, and a mission
to study a potentially habitable planet there could take as little as two centuries with
this technology.
That likely means the mission won't be manned, but will instead be piloted by an artificial
intelligence capable of making critical decisions on its own since radio communications will
take over 118 years to reach us, and another 118 years to receive a reply from home.
The problem with beamed laser propulsion however is slowing down- since there's no emitters
at the destination to slow you down, the first mission to WD 1054-226 will need to be equipped
with an engine for slowing down.
However, future missions could carry self-replicating probes which could break down local asteroids
to use as building materials and create a series of laser emitters within the WD 1054-226
system.
Then the next mission to WD 1054-226 would be even lighter and speedier as it wouldn't
need to carry an engine and the reaction mass to slow itself down.
In fact, we could create entire superhighways across the galaxy by simply sending probes
to build laser emitters further and further out from earth, allowing mankind to spread
across the galaxy on highways made of laser light.
Though the first mission to WD 1054-226 would be unmanned, a manned mission would still
be possible in the future if we should find a habitable planet there.
These centuries-long voyages though would likely require crews to commit to generational
ships, or ships where multiple generations of humans will live and die before arriving
at their destination.
In essence, the first generation would be the ones to leave earth, raising a second
generation to crew the ship while in transit.
Then a third generation would be the ones responsible for actually arriving at WD 1054-226
and setting up a human colony there.
That would certainly require quite a few breakthroughs in technology, including the ability to build
ships big enough that they could host entire generations of humans without any of them
going stir crazy.
But if we can find a way to slow down the aging of human bodies, or just get rid of
them altogether, we might be able to simply hack our brains into making the trip seem
like it's only a few days long.
Stasis ships are a common science fiction trope, but it's not known if we'll ever truly
be able to develop a technology that can put a human body in indefinite stasis and revive
it again.
Currently there's hundreds of people who have been cryogenically frozen, hoping they can
be thawed out with future technology and revived.
Hate to break it to these people, but at the moment all they're really doing is creating
trash for future generations to dispose of.
But if the body's metabolism could be slowed down sufficiently, to perhaps a fraction of
its normal speed, a single generation of humans may be able to make the trip without suffering
more than a few decades of aging.
Their bodies might not even age at all if they're being tended to the entire time by
nanomachines which constantly work to repair DNA damage, which is the real source of aging
as damaged DNA replicates and creates more, damaged copies of itself.
A better solution yet would be to simply get rid of the body altogether.
Future astronauts might simply ditch their bodies and upload their minds to a computer,
then have their body broken down and stored as future nutrients.
Once arriving at their destination, the ship's AI would automatically grow new bodies for
the crew, which could be perfectly cloned copies of their original selves.
But what would the uploaded consciousness be doing for over two centuries of travel
time?
Thanks to living inside a computer, each mind could simply be 'slowed down' artificially
to the point that the passage of an entire year in the real world could be nothing more
than a single second for the crew.
Thus a journey of 200 years could be reduced, at least in the perception of the crew, to
a month- or a week.
A single hour even, there's practically no limit to how slow a mind could be run once
uploaded on a computer.
Even in the near-future, getting to WD 1054-226 is not going to be much of a problem for humanity-
the real question is if it's even worth going.
As of right now, the evidence is strong that a planet the size of one of the solar system's
rocky planets exists around the small white dwarf, and smack-dab in the middle of its
habitable zone.
But the odds of life evolving and surviving around a white dwarf are pretty astronomical,
though not impossible.
Only future observations will tell us if WD 1054-226 is worth visiting or not.
Now go check out What If There Was War In Space?
Or click this other video instead!