For a long time, scientists have been looking for planets that are
potentially habitable. So far millions of planets have been discovered and more
are being discovered every day. Until now, we thought
that there is no planet like us anywhere in the universe. But recently
scientists have claimed that they have discovered planets that can be more habitable
than Earth. But do such exoplanets really exist?
Rendering
of an exoplanet. Source: Ricardo
Ramirez/NASA
What are Exoplanets?
Any world orbiting a sun or a star outside our solar system is called an exoplanet or extrasolar planet. The maximum size of these exoplanets can be equal to the gas-filled planet Jupiter in our solar system and at least small rocky planets like Mars or Earth. Most of these discovered planets are lie in a small area of the milky way galaxy, and observations from NASA's Kepler space telescope mission have shown us that there are more planets in this region than stars. The first exoplanet was discovered in the 1990s and since then we have discovered thousands more planets using many different techniques, although finding them is not an easy task. There could be at least 300 million potentially habitable exoplanets in our milky way galaxy alone. The U.S space agency's Kepler space telescope's planetary exploration mission lasted nine years and identified thousands of exoplanets in our galaxy before running out of fuel in 2018. According to all the data collected by Kepler, there are 300 million rocky planets that are capable of keeping liquid water on their surface. Although this is only a rough estimate because there are about 100 to 400 billion stars in the galaxy and each of these stars may have at least one planet around it, which means that there are potentially trillions of planets.
Hertzsprung-Russel
Diagram by ESO
How to find exoplanets?
You might think that finding them is as easy as using a telescope, but seeing an exoplanet the way you see Saturn from Earth is extremely difficult, this is called direct imaging and very few exoplanets have been discovered this way. Most exoplanets have been discovered using the transit method that measures the dimming of a star when a planet passes in front of it. We can also discover exoplanets by measuring the spectrum of the star's light, by measuring the effects of the planet's attraction to the star that causes the light to shift, or by using gravitational lensing. Using all these factors together enables us to find countless exoplanets in the vast universe every day.
Artistic rendering of the so-called Goldilocks
zone Source: NASA
If
we want to find exoplanets that could support signs of life, we must first look
for planets that orbit their stars in the habitable zone, which some scientists
call the Goldilocks Zone. It’s a region around any star that is neither too hot
nor too cold for the existence of liquid water, but that alone is not enough for
a planet to be habitable, the size of the planet and the type of the star
around which the exoplanet orbits has to be a certain type and stable. As our
yolk-inclined sun has been stable for more than 4.5 billion years, this has not
always been observed in the existence of different stars in other systems. As our
own yellowish dwarf sun has been stable for more than 4.5 billion years, this
has not always been observed in the existence of different stars in other
systems. has had a stable existence for over 4.5 billion years, whereas other
systems have not always been observed to have such stable stars.
Proxima' b image source: ESO
Proxima`
b
The
planet Proxima b was discovered in 2016 using the HARPS telescope, located at
distance of 4.2 light-years from Earth, and is currently the nearest known
alien exoplanet to our solar system. It is positioned in the habitable zone of
its red dwarf star, Proxima Centauri, and was initially thought to be at least
1.3 times larger than Earth. However, recently discovered facts using the new
ESPRESSO Telescope have shown that Proxima b is only 17 times bigger than
Earth, and is potentially habitable due to its location within the star's habitable
zone, an appropriate distance from its star, where liquid water can exist. Initially,
scientists believed that this planet could be habitable and that with the future
generations of super-fast spacecraft, the search for life could be made towards
this planet. However, in the same year, a huge solar flare erupted from Proxima
Centauri, which was over 1000 times brighter than the red dwarf star itself and
The flare hit Proxima b with 4000 times more ultraviolet radiation than the
Earth would receive from a solar flare from our sun, and researchers speculate
that it may have wiped out all signs of life on Proxima b. However, its not the
only habitable planet.
Recently scientists have claimed the discovery of 24 super habitable exoplanets or exo moons that could be more suitable for life’s emergence, existence and evolution.
Potentially
Habitable Planets image source: ESA
Gliese
667cc image source: Planetary Habitability Laboratory.
Another super-habitable exoplanet, Gliese 667cc, is the next-closest planet to Earth and orbits a red dwarf star in the triple star system of Glee 667. Yes, three stars, meaning if you were standing on the surface of Gliese 667cc, you would see these three stars on the sky during the day. Gliese 667cc is located at a distance of 23.62 light-years from our planet Earth and has a minimum mass of 3.7 times that of Earth. Gliese 667cc is the next closest super-habitable exoplanet which orbits a red dwarf star in the glee 667 triple star system. Yes, three stars, if you were standing on Gliese 667cc this is likely what you would see in the day sky. Gliese 667cc is located at 23.62 light years from earth and is a minimum of 3.7 earth masses.not an easy task.
The next possible super habitable
world could be kepler-452b. It's sometimes Kepler-452b could potentially
be another super habitable world. It is sometimes called as "Earth
2.0". This planet orbits a G-type star similar to our Sun and is located
approximately 1.5 billion years older than Earth and is much larger than our
planet. Some authors speculate that there may be an ancient civilization on one
of its moons. It is possible that we are glimpsing into the future of Earth, as
the star around which this planet orbits are using up its fuel and has expanded
into a red giant star. But there is still much to be discovered and explored.
As
of yet, no reliable method has been discovered to detect oxygen on any planet.
However, we hope that things will change soon. On December 25th, 2021, the
James Webb Space Telescope was launched into space on an Ariane 5 rocket. The
technology on this telescope is different from any design, and it is considered
an alternative to the Hubble Space Telescope. It is a new and powerful tool for
searching and studying exoplanets that support life. The James Webb Telescope
has set its base outside the orbit of the moon, 930,000 miles from Earth, and
is orbiting around the sun. It is the largest observatory ever sent into space
and is using special new optical science and engineering for the exploration of
hidden secrets of the universe.
Illustration
by J. Krissansen-Totton
According to researchers, a new technique has been developed that enables the James Webb telescope to identify a distinctive signal created by the collision of oxygen molecules. The discovery of this signal in the atmosphere of an exoplanet would suggest the presence of oxygen and potentially life, as we know it, on the planet's surface. However, despite this incredible technology, the James Webb telescope must be positioned within 16 light-years of a habitable exoplanet orbiting a red dwarf with an atmosphere comparable to Earth's to detect the oxygen signal. The James Webb telescope, launched in 2021, will explore the universe's history, including the distances between exoplanets, other galaxies, the initial bright moment of the big bang, and the evolution of our solar system. Nonetheless, we might need even more powerful instruments to observe deeper into space.
Nancy Grace
Roman Space Telescope: NASA.gov/roman
The Nancy grace roman telescope will be launched sometime in the later 2020s and scientists said that will have 100 times the viewing field compared to the hubble space telescope. It'll probe the depths of dark matter and dark energy the mysterious and mostly unknown phenomena that makes up most of the universe. The most exciting thing is it'll be able to make direct images of exoplanets something not possible from planet earth. But the main goal of its mission is to peer into the interior of the milky way galaxy, where it would possibly find thousands more exoplanets through gravitational microlensing. It is important to keep in mind that even if we discover life in outer space, the universe is a diverse and fascinating place, and the most suitable environment for life, such as super habitable worlds, may not resemble Earth in any way. We traditionally imagine we're entering a very exciting time in human technology and with the number of habitable worlds out there It's likely that we'll finally discover life on a distant world.
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