Astronomers have spotted an extraterrestrial planet around Proxima Centauri, the sun's
nearest neighbor.
Proxima b is a planet that is just slightly larger than Earth.
It orbits in the star's habitable zone, which implies liquid water — and maybe life — might
exist there.
Despite its Earth-like characteristics, Proxima b is a strange, alien world.
NASA scientists have spent a significant amount of time researching this strange world in
order to uncover all of its mysteries.
What have they discovered about this amazing planet?
Is there life on it?
Join us as we look into NASA's findings on Proxima b, which expose all of its mysteries!
The discovery of another planet was announced less than six years ago.
This planet, known as Proxima Centaur b or just Proxima b, is classified as an exoplanet
due to its position outside the solar system.
Astronomers have discovered a huge and rising number of Earth-sized exoplanets circling
distant stars in recent years.
Some are in their stars' habitable zones, where temperatures may enable liquid water
to exist on their surfaces.
However, astronomers were particularly delighted by Proxima Centauri b since the sun it circles
is the nearest star to our solar, barely 4.2 light-years away!
Guillem Anglada-Escude and a team of astronomers from the Pale Red Dot initiative discovered
Proxima b.
Its existence was verified using the ESO 3.6-meter telescope's High Accuracy Radial Velocity
Planet Searcher, or HARPS spectrograph, using a process called as Doppler Spectroscopy or
the Radial Velocity Method.
This approach involves monitoring the spectra of stars for evidence of "wobble," which occurs
as a star moves closer and further away from Earth.
This is created by the gravitational impact of planets orbiting the star, the extent of
which is used to calculate the planets' masses.
Astronomers derived a minimum mass estimate of 1.24 Earth masses and a maximum mass estimate
of 2.06 Earth masses for Proxima b.
The existence of Proxima b was verified once more in 2020 by the European Southern Observatory's
Very Large Telescope (VLT) and its Echelle Spectrograph for Rocky Exoplanet and Stable
Spectroscopic Observations (ESPRESSO).
The Transit Approach was used to discover the majority of exoplanets identified to date,
however for a star like Proxima Centauri, a low-mass and less luminous M-type or red
dwarf star, the method proved ineffective.
With a mass of 1.17 Earth masses, Proxima Centauri b is quite comparable in size to
Earth.
In comparison to our Earth's year-long orbit around the sun, it circles its star in just
11.2 days.
That implies that Proxima Centauri b is far closer to its star than Earth is to the sun.
However, because the star is a red dwarf, which is considerably smaller and colder than
our sun, its orbit falls within Proxima Centauri's habitable zone.
Surprisingly, Proxima Centauri b receives almost the same amount of solar radiation
from its star that Earth does from our sun!
This means that water may exist on the surface of Proxima Centauri b.
It might be livable, but we don't yet know all the intricacies concerning extraterrestrial
habitability.
However, numerous elements influence a planet's habitability, including temperature, the makeup
of the planet and atmosphere, the presence or absence of water, and solar radiation.
Red dwarfs, like as Proxima Centauri, are known to generate flares, which complicate
and fascinate the habitability of red dwarf exoplanets.
Scientists sought to ascertain if this exoplanet may sustain life after astronomers confirmed
its existence in 2016.
Sure, it was in its star's habitable zone, but several studies immediately threw doubt
on the possibility of extraterrestrial life!
As a result, the question of whether life may exist on Proxima b has constantly split
scientists!
All of these studies, however, imply that this topic will remain unanswered until astronomers
analyze Proxima b's atmosphere, preferably by watching it when it passes in front of,
or transits, its host star.
However, a team led by astrophysicists at the University of Chicago decided in recent
NASA-supported research that this is an improbable option.
Emily A. Gilbert, a Graduate Student in the Department of Astronomy and Astrophysics at
the University of Chicago, conducted the paper that described their findings.
She was accompanied by experts from The Adler Planetarium, the University of Maryland's
Center for Space Science and Technology, and the NASA Goddard Space Flight Center's Exoplanets
and Stellar Astrophysics Laboratory.
Still, even if life does exist on Proxima b, there remains a major obstacle that must
be overcome.
It's referred to as space weather!
When you hear about the weather as an earth inhabitant, you automatically think of the
sun, clouds, rain, wind, and so on.
If you're familiar with weather on other planets or moons with atmospheres, you could think
of that type of weather as well.
However, none of this is connected to space weather.
It's a type of "weather" that begins in stars, including our sun, and pervades the space
around them.
Ionizing radiation emitted by flares on the sun or other stars is what causes space weather.
Any life forms on faraway worlds might be eliminated by the radiation.
This is especially true for red dwarf stars, which experience more frequent flares than
our sun, according to scientists.
Red dwarf stars could be extremely unpredictable, and Proxima Centauri happens to be one!
Radio waves were utilized by astronomers at the University of Sydney in Australia to identify
and explore the space weather near Proxima.
At least two planets are known to circle our sun's closest neighbor.
One is Proxima Centauri b, which has almost the same mass as Earth, while the other is
Proxima Centauri c, which is roughly seven times more massive!
Proxima Centauri b also orbits within the habitable zone of its star, where temperatures
may permit liquid water to exist on the planet's surface.
If you're hoping to see these as a sign of life, you'll be disappointed!
The discovery of flares on stars such as Proxima suggests a bleak future for life on the planets
in this system.
Because it is so close to the star Proxima Centauri, Proxima Centauri b is vulnerable
to powerful outbursts of ionizing radiation from its star!
It is crucial to note that just because an exoplanet is in the habitable zone does not
indicate it can be colonized.
This is true of Proxima b!
Proxima Centauri is a cold, compact red-dwarf star, which means the habitable zone is quite
close to the star; in fact, it is considerably closer to the star than Mercury is to our
sun.
According to research, this puts the planets very sensitive to hazardous ionizing radiation,
which might essentially sterilize the planets.
Our own sun, however, emits hot clouds of ionized particles on a regular basis during
what are known as 'coronal mass ejections.'
However, because the sun is much hotter than Proxima Centauri and other red-dwarf stars,
our 'habitable zone' is far from the sun's surface, implying that the Earth is a relatively
long way from these events, and thus this radiation does not affect us as strongly!
Furthermore, the Earth has a very strong planetary magnetic field that protects us from these
powerful solar plasma blasts.
Scientists may conclude from analyzing the space weather near Proxima Centauri that all
red dwarf stars are not the best settings for life.
However, other elements may be at work here for any specific planet, such as how far it
is from the star, how powerful its magnetic field is if it has one, and so on.
Some red dwarfs are presumably more active than others in comparison.
As a result, drawing broad statements about red dwarf scenarios is challenging.
When high-energy extreme ultraviolet light ionizes atmospheric molecules, knocking off
electrons and generating a swath of electrically charged particles, an active red dwarf star
like Proxima Centauri tears away the atmosphere.
The freshly generated electrons gather enough energy during this process to easily escape
the planet's gravity and dash out of the atmosphere.
As more negatively charged electrons leave the atmosphere, they generate a tremendous
charge separation that draws positively charged ions out into space with them.
Proxima Centauri's habitable zone contains bursts of severe ultraviolet radiation hundreds
of times stronger than what Earth receives from the sun.
That radiation provides enough energy to tear away not just the lightest molecules, hydrogen,
but also heavier elements like oxygen and nitrogen over time!
According to the model, Proxima Centauri's intense radiation evaporates the Earth-like
atmosphere 10,000 times quicker than what happens on Earth!
The scientists looked at two more elements that worsen atmospheric loss to better understand
how the process might differ.
They began by considering the temperature of the neutral atmosphere, known as the thermosphere.
They discovered that as the thermosphere warms due to increased solar radiation, atmospheric
escape rises!
In addition to investigating the likelihood of life on Proxima b, scientists have attempted
to establish what the Earth might look like as a planet if it orbited Proxima Centauri.
They conducted simulation to figure out what the situation would be like!
We're back to the idea of livable zones.
Proxima b's orbit is in the habitable zone, which corresponds to the distance from its
host star where water may pool on the planet's surface, but that doesn't imply it's habitable.
It does not consider, for example, whether water exists on the planet or if an atmosphere
might exist in that orbit.
Atmospheres are also necessary for life as we know it because they allow for climate
management, the preservation of water-friendly surface pressure, protection from dangerous
space weather, and the preservation of life's chemical building components.
The computer model employed by the scientists used Earth's atmosphere, magnetic field, and
gravity as proxy for Proxima b's.
They also computed how much radiation Proxima Centauri emits on average, using data from
NASA's Chandra X-ray Observatory.
Using this data, their model predicts how the exoplanet's atmosphere is affected by
the host star's powerful radiation and periodic flares.
Even with cutting-edge technology, reaching our nearest nearby star would take thousands
of years.
For the time being, visiting Proxima b is out of the question.
Meanwhile, scientists will continue to examine the planet from afar.
They'll be looking for signs of water — and possibly alien lifeforms.
Let us know what you think of life on Proxima b in the comments section below.