When will we reach the new earth Proxima Centauri b?
Today I'm bringing you guys with me on a trip to the closest
potentially habitable exoplanet to Earth. The only thing is...I don't actually know
how to reach it. It's not about the map. It's about the transport method.
Even being the closest, its distance is still too much for our technology.
It would take too long for us - better saying, for our probes - to reach Proxima Centauri b.
Sure is that, if we ever managed to land on that planet, we would have a beautiful night view from
its surface. In fact, from Proxima Centauri b, the binary stars Alpha Centauri would be
considerably brighter than Venus is from Earth. And the Sun would appear as a relatively bright
star with an apparent magnitude of 0.40 in the constellation of Cassiopeia.
In other words, the brightness of the Sun would be similar to that of Achernar or Procyon from Earth.
But it will be difficult to even fly by the planet, due to the huge distance from Earth.
In any case, I promise I will think about an efficient transportation method.
But how much does this distance account for?
It is approximately 4.2 light-years from Earth in the constellation Centaurus. This
means that it would take us more than 4 years, traveling at the speed of light, to get there.
Proxima b is orbiting in the habitable zone of the red dwarf star Proxima Centauri,
which is the closest star to the Sun and part of the triple star system Alpha Centauri.
Proxima Centauri b orbits its star at a distance of roughly 0.05 AU
(7.5 million km; 4.6 million mi) with an orbital period of 11 Earth days. This
means that we would sing happy birthday to you approximately every 264 hours.
Its other properties are only poorly understood,
but it is believed to be a possibly Earth-like planet with a minimum mass of 1.07 Earth masses.
From observations, it seems the planet orbits within the habitable zone of its star.
It is, however, not known whether or not it has an atmosphere.
This is a challenging topic, a matter of debate.
One of the major problems could be that red dwarfs are kind of
evil stars. They emit flares with intense emissions of electromagnetic radiation that
could rip the entire atmosphere off the planet, which would mean...uhm...no life allowed!
In this video, we are going to further talk about Proxima b, and the ways we might have to reach
the exoplanet. Spoiler: we might have found a way to travel at one-fifth the speed of light!
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Proxima Centauri was a target for exoplanet searches way before
Proxima Centauri b was discovered, but initial studies in 2008 and 2009
ruled out the existence of larger-than-Earth exoplanets in the habitable zone.
Planets are very common around dwarf stars - this is what the most common stars in the
universe are called. Actually, astronomers think that, on average, every dwarf star
has 1 or 2 planets orbiting around it. The Sun, for example, is roughly a Yellow dwarf.
Perhaps the most exciting thing is knowing that about 20 to 40% of all red dwarfs
have one in the habitable zone.
Before 2016, some scientists at ESO (European Southern Observatory)
conducted observations and found some anomalies in Proxima Centauri
which could not be explained by flares[ or chromospheric activity of the star.
Maybe that was a chance for it to host a planet.
Maybe Proxima Centauri was one of the millions of dwarf stars that own a planetary system.
That's why, in January 2016, a team of astronomers launched the Pale Red Dot project to confirm this
hypothetical planet's existence. On 24 August 2016, the team led by
Anglada-Escudé proposed that a terrestrial exoplanet in the habitable zone of Proxima
Centauri could explain these anomalies and announced Proxima Centauri b's discovery.
The discovery of Proxima Centauri b, a planet at habitable distances from the closest star
to the Solar System, was a discovery, - I would say, a major one - in planetology
and has drawn interest to the Alpha Centauri star system that Proxima is a member of.
However, we are sad to inform you that, in a new study, researchers used nine ground and orbital
telescopes - including the Hubble Space Telescope, the Atacama Large Millimeter/submillimeter Array,
and NASA's Transiting Exoplanet Survey Satellite - to closely monitor Proxima Centauri for a total
of 40 hours over several months in 2019. What they found, is that the star emitted a
mega flare, which shone for just 7 seconds and was mainly visible in the ultraviolet spectrum.
"The star went from normal to 14,000 times brighter when seen in ultraviolet wavelengths over
the span of a few seconds," lead author Meredith MacGregor, an astrophysicist at the University
of Colorado Boulder, said in a statement. As we've already said, red dwarfs are evil stars.
Their flares can rip away the planets' atmospheres.
This could then change what we know about red dwarfs and the chances of
life developing on the planets that orbit them.
Proxima b orbits its host star at a distance of about 0.049 Astronomical Unis,
which is over 20 times closer than Earth is to the Sun.
We don't really know about the age of the planet. Usually,
the age of a planet is estimated from the age of its host star, so when we say we don't know
the age of Proxima b, we are basically saying that we don't know the age of the red dwarf.
This is because Proxima Centauri is part of a system of stars, and it might have been captured
by Alpha Centauri and thus not necessarily of the same age as the latter, about 5 billion years old.
From exoplanetary science studies, we know that the estimated minimum mass of Proxima Centauri b
is about one Earth mass, but these estimates are blind to the inclination of the planet's orbit,
which enters the equations for the mass, and may be underestimated.
So we could imagine that this planet is really similar to Earth, but of course, the mass is
not the only parameter we need to come to such conclusions. Maybe, if we knew something about the
radius of the planet, we could say something more. But it is really difficult to infer a precise
measurement of the radius. Depending on the composition,
Proxima Centauri b could either be a Mercury-like planet with a large core-which
would require particular conditions early in the planet's history-to a very water-rich planet.
As you can understand, we don't really know much about Proxima b,
and I'm expecting that in the next years we will have more precise and new measurements.
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What astronomers and astrophysicists do when they have poor data,
is make simulations and see if those simulations match the observations.
According to simulations, Proxima Centauri b likely developed under different conditions
from Earth, with less water, stronger impacts, and overall faster development,
assuming that it formed at its current distance from the star.
But another intriguing feature is that Proxima Centauri b
probably did not form at its current distance to Proxima Centauri.
This would be the case of a so-called planetary migration.
In short terms, the planet - or fragments of the planet - formed
at larger distances and then migrated to the current orbit of Proxima Centauri b.
A number of different formation scenarios are actually possible, many of which depend on the
existence of other planets around Proxima Centauri and which would result in different compositions.
Well, at the beginning of the video I promised you we would have found a way to reach Proxima b.
In the last decades, scientists have been thinking of some clever traveling methods
to make us, humans, an interplanetary race.
This would basically mean, finding a more efficient way to travel, a way that could
speed us up to - possibly - the speed of light. Or at least up to a fraction of it.
The Breakthrough Starshot initiative could seem to be the most promising one.
The idea is to send wafers into space. Let me explain it better.
You have wafer-thin probes, so thin that they can be pushed by beams of electromagnetic radiation.
Basically, the concept is to use beams of light to push these super thin and super light probes
into space, thus exploiting the radiation pressure of the light on a surface, the probes' surface.
This laser would accelerate the probes to 20 percent the speed of light (about 134.12
million mph, or 215.85 million km/h), according to the program scientists.
At that rate, the probes could reach Proxima Centauri in 20 to 25
years. This is still a dream, but we really hope one day it will become reality.
The thing is, one thing is the theory, and another thing is the real world.
First, scientists and engineers have to build the apparatus that will launch
the tiny probes on their journey. We might have a first model in the upcoming years,
but scientists speculate that the full-scale apparatus is at least 20 years off.
We certainly hope that, within a generation, we can launch these nanoprobes.
And so perhaps 20, 25 years from now, we could begin to launch them,
and then they would travel for 25 years to get there.
Scientist Worden, responsible for the project, said that building the full-scale apparatus would
likely cost about the same as building the Large Hadron Collider, the largest particle
accelerator in the world; that project is estimated to have cost about $10 billion.
In order to understand the huge distance that separates us and the exoplanet,
let's try to make some comparisons.
In 2015, NASA's New Horizons probe completed
its 4.8 billion km journey to Pluto after traveling for about 9.5 years.
The spacecraft traveled at speeds topping 84,000 km/h).
At that rate, it would take New Horizons about 54,400 years to reach Proxima Centauri!
And even if we reached the speeds of Juno's spacecraft, something like 265.000 km/h,
it would take us 17,157 years.
In other words, sending a probe to the nearest star system would not be easy, at all.
But once we manage to send these probes, we could decide to take a snapshot of the planet.
What would you think we will find? Maybe we will be able to see vast
oceans on the surface of this beautiful exoplanet, or maybe we will be able to
find out that the atmosphere had been ripped apart by the star's flares.
At the moment, we don't even have a picture from Earth.
As of 2021, Proxima Centauri b has not yet been directly imaged, as its separation from Proxima
Centauri is too small for that. It is unlikely to transit Proxima Centauri from Earth's perspective;
all surveys have failed to find evidence for any transits of Proxima Centauri b.
I guess... we will have to wait.
Thanks for watching everyone! What do you guys think of Proxima b?
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