by:Aayush and Samruddhi
Exoplanets, as fancy as the name goes, do we actually know what an exoplanet really is? Why
are they called so? And why are exoplanets always mentioned besides the actual name of the
Remember when we were first taught about the earth we were told that it’s one of a kind. Yes! We
were undoubtedly naïve. Space indeed has tons of systems and galaxies to offer which are
inconceivable. We barely even knew our galaxy and yet we found success in discovering
planets outside of our solar system that are thousands of light-years away from us. Such planets
are exoplanets. The first-ever exoplanet was discovered a few decades ago and since then
we’ve discovered thousands using various detection methods. The first-ever exoplanets to be
discovered were PSR B1 257+12 and PSR 1620-26 by Aleksander Wolszczan and Dale Frail.
It was located 1170 light-years from Earth. There are theories that say that the first exoplanet
notes were in 1917 but remained unrecognized. Detection of such planets is not a stone’s throw
at all. NASA‘s Kepler space telescope, an observatory that began work in 2009 has been the
most efficient to uncover such exoplanets.
Kepler has discovered 2,342 confirmed exoplanets. The total number of planets discovered by
all observatories is 3,706. The existence of exoplanets is proof that we are way secluded from
knowing the true forces of astronomy. HD 219134 b is the closest exoplanet to Earth to be
detected transiting in front of its star. Many of the exoplanets show resemblance to Earth in terms of
size, mass, density etc. Kepler 452-b is quoted as “EARTH 2.0” owing to its characteristics. Apart
from Kepler’s method, there are several detection methods like Astrometry which is to detect tiny
changes in a star’s position caused by the presence of exoplanets. So far scientists have classified
exoplanets into four categories namely- Gas Giant,Neptunian, Super Earth, and Terrestrial.
While exoplanets were not confirmed until the 1990s, for years beforehand astronomers
were convinced they were out there. Astronomers had an origin story for our solar
system. Simply put, a spinning cloud of gas and dust (called the protosolar nebula)
collapsed under its own gravity and formed the sun and planets. As the cloud collapsed,
conservation of angular momentum meant the soon-to-be-sun should have spun faster
and faster. But, while the sun contains 99.8 percent of the solar system’s mass, the
planets have 96 percent of the angular momentum. Astronomers asked themselves why
the sun rotates so slowly. Most stars like the sun rotate slowly, so astronomers inferred
that the same “magnetic braking” occurred for them, meaning that planet formation
must have occurred for them. The implication: Planets must be common around sun-like
stars. For this reason and others, astronomers at first restricted their search for
exoplanets to stars similar to the sun, but the first two discoveries were around a pulsar
(rapidly spinning corpse of a star that died as a supernova) called PSR 1257+12, in
- The first confirmed discovery of a world orbiting a sun-like star, in 1995, was 51
Pegasi b — a Jupiter-mass planet 20 times closer to its sun than we are to ours. But
another oddity popped up seven years earlier that hinted at the wealth of exoplanets to
come.A Canadian team discovered a Jupiter-sized planet around Gamma Cephei in
1988, but because its orbit was much smaller than Jupiter’s, the scientists did not claim
a definitive planet detection.
Now this was all about exoplanets, their discoveries but what about their existence?
Well here is the example of an Sun-Earth system like exoplanet-star, Kepler-160 &
Kepler-160 & KOI-456.04, Sun-Earth system like exoplanet-star
The star Kepler-160 and its companion KOI-456.04 are more reminiscent of the Sun-Earth
system than any previously known exoplanet-star pair, according to a team of scientists led by
the Max Planck Institute for Solar System Research (MPS) in Gottingen, Germany. The star
Kepler-160 is probably orbited by a planet less than twice the size of the Earth with a star-planet
distance that could permit planetary surface temperatures conducive to life. The newly
discovered exoplanet is more than just another potentially habitable world. One of the key
properties making it resemble the Sun-Earth system more than any other previously known
world is its Sun-like host star. Most of the Earth-like exoplanets known so far are in orbit around
a faint red dwarf star emitting their energy mostly as infrared radiation rather than as visible
Kepler-160 and KOI-456.04 are the most Sun and Earth-like system ever Found
● Sun-Earth Comparison Index:
- At a distance of just over 3,000 light-years from the solar system, the star Kepler-160
was located in the field of view of the Kepler primary mission and was continuously
observed from 2009 to 2013. Its radius of 1.1 solar radii, the surface temperature of
5,200 degrees Celsius (300 degrees less than the Sun), and it’s very Sun-like stellar
luminosity makes it an astrophysical portrayal of our own parent star. Kepler-160 has
been known for about six years to be a host star of two exoplanets, called Kepler-160b
and Kepler-160c. Both of these planets are substantially bigger than Earth and in
relatively close orbits around their star. Their surface temperatures would certainly make
them hotter than a baking oven and everything but hospitable for life as we know it. But
tiny variations in the orbital period of planet Kepler-160 c gave scientists a signature of a
third planet that had yet to be confirmed.
- KOI-456.04, probably a transiting planet with a radius of 1.9 Earth radii and an orbital
period of 378 days. Given its Sun-like host star, the very Earth-like orbital period results
in very Earth-like insolation from the star — both in terms of the amount of the light
received and in terms of the light colour. Light from Kepler-160 is visible very much like
sunlight. All things considered, KOI-456.04 sits in a region of the stellar habitable zone —
the distance range around a star admitting liquid surface water on an Earth-like planet —
that is comparable to the Earth’s position around the Sun. KOI-456.01 is relatively large
compared to many other planets that are considered potentially habitable. But it’s the
combination of this less-than-double the size of the Earth planet and its solar-type host
star that makes it so special and familiar. As a consequence, the surface conditions on
KOI-456.04 could be similar to those known on Earth, provided its atmosphere is not too
massive and non-Earth-like.
- The amount of light received from its host star is about 93 per cent of the sunlight
received on Earth. If KOI-456.04 has a mostly inert atmosphere with a mild Earth-like
greenhouse effect, then its surface temperature would be +5 degrees Celsius on
average, which is about ten degrees lower than the Earth’s mean global temperature.
- The light shed on KOI-456.04 by its Sun-like host star, however, is very much like the
daylight seen on our home planet. Moreover, the orbital period of KOI-456.04 around its
Sun-like star is almost identical to an Earth year.
Now that’s surprising! A planet which is look-alike and has Sun-Earth like properties! But what
about only Earth-like exoplanets? Do they exist too? And on what basis can we
differentiate between them and Earth? Well here are some detailed concepts about an
Earth-like exoplanet, Kepler-425b.
Kepler-425b, an Earth like exoplanet
Kepler-452b is a super-Earth exoplanet orbiting within the inner edge of the habitable zone of the
Sun-like star Kepler-452, and is the only planet in the system discovered by Kepler. It is located
about 1,402 light-years (430 pc) from Earth in the constellation of Cygnus.
Comparison about size of Kepler-452b versus Earth with host stars Kepler-452 and Sun
The planet sometimes quoted to be an Earth 2.0 or Earth’s Cousin based on its characteristics;
● Earth Comparison Index:
- Kepler-452b orbits its star at a distance of 1.04 AU (156,000,000 km; 97,000,000 mi) from
its host star (nearly the same distance as Earth from the Sun), with an orbital period of
roughly 384 days, has a mass at least 5x times that of Earth, and has a radius of around 1.5
times that of Earth. It is the first potentially rocky super-Earth planet discovered orbiting
within the habitable zone of a star very similar to the Sun. However, it is not known if it is
completely habitable, as it is receiving slightly more energy than Earth is, and could possibly
be subjected to a runaway greenhouse effect.
- The exoplanet was identified by the Kepler space telescope, and its discovery was
announced by NASA on 23 July 2015. The planet is about 1,800 light-years away from the
Solar System. At the speed of the New Horizons spacecraft, about 59,000 km/h (37,000
mph), it would take approximately 30 million years to get there.
- Kepler-452b has a probable mass five times that of Earth, and its surface gravity is nearly
twice as Earth’s, though calculations of mass for exoplanets are only rough estimates. If it is
a terrestrial planet, it is most likely a super-Earth with many active volcanoes due to its
higher mass and density. The clouds on the planet would be thick and misty, covering much
of the surface as viewed from space.
- The planet takes 385 Earth days to orbit its star. Its radius is 50% bigger than Earth’s, and
lies within the conservative habitable zone of its parent star. It has an equilibrium
temperature of 265 K (−8 °C; 17 °F), a little warmer than Earth.
Brother, am I larger than you or Viceversa?
Most of the first exoplanet discoveries were huge Jupiter-size (or larger) gas giants
orbiting close to their parent stars. That’s because astronomers were relying on the
radial velocity technique, which measures how much a star “wobbles” when a planet or
planets orbit it. These large planets close in produce a correspondingly big effect on
their parent star, causing an easier-to-detect wobble.
Detailed study shape wise
Bro I have life, what about you? Existence of Habitat
Being a brother from a different mother to Earth, Sun and other members of our galaxy, these
planets do possess similar characteristics even proved to have an atmosphere with traces of land
and water but that’s not enough for what we call as existence of habitat. Though these planets can
be excellent backup planets for habitats to survive or can even be the planets having life but of a
different kind. Also we don’t have the adequate amount of investment resources to reach these
brothers of Earth.
Reports are still ongoing and every detailed study about the existence of life is still being searched.
But what will be the reaction of our alien brothers on seeing us if they exist?
These existence kinda highlights that the mythologies of different GODs acting like brothers might be
true in a metaphorical sense and also the conspiracy theories gives rise to different kinds of
explanation about these which, till now does not clearly explain whether another multiverse exists or
not or simply a twin Earth exists or not within the undiscovered part of the universe. If that’s true then
is our Earth in profit or danger and will the other look-alike brothers come to take their fair share?
Another conspiracy arises…
After a thesis over exoplanets, we have reached a standstill to the fact that there exists a realm of
revelations that are yet to unfold. Space remains mystical and it’s true it will take more decades and
more centennial for these mysteries to unravel. If such unravelling is ever bound to happen then we
might also find our planet twin! Yes, a place indistinguishable from earth with exact characteristics,
properties of earth where living is a possibility. It clearly is a theory but if such theories roll out it
might be one of the greatest discoveries of mankind. It’s a mere possibility but if exoplanets exist
there is a teeny tiny possibility for the twin to be found. It might take us zillions of years to bust out
many such theories related to space and astronomy. It’s so vast and limitless that it’s actually scary
what we might come across with more new research and findings. Whatever progress we make be
in technology, space ,sciences and every other field what matters is our dedication and hard work.
As human beings on this planet earth, it’s our faith to unlock the mysteries of nature.