The curiosity to find earth-like planet can be dated to long time ago. But because of the incapability of the available technologies, it was a dream to detect planets beyond our solar system. After the time stated, the space research have taken a new leap and opened a new era of information. The concept of Exoplanet born. It can also be referred to as Extra Solar Planet. Any planet which is not within our solar system is Exoplanet. But an absolute definition is quite complex and problematic. So some of the important characteristics of an Exoplanet is it has to be earth-like environment, it can be giant or terrestrial type

1. Essay on
Exoplanet

2. Table of content
Contents
Introduction................................................................................................................................... 2
Exoplanets ................................................................................................................................... 2
First Exoplanet: 51 Pegasi b........................................................................................................ 2
Total Exoplanets discovered ....................................................................................................... 2
Aim of the Report........................................................................................................................ 3
The methods of searching Exoplanets.......................................................................................... 4
The stars we are looking for........................................................................................................ 4
‘Super Earths’ and ‘Hot Jupiters’................................................................................................ 4
The concept of a “Habitable Zone”............................................................................................. 4
The techniques of detecting Exoplanets...................................................................................... 4
The radial velocity method ...................................................................................................... 5
The astrometry method ............................................................................................................ 5
The transit method ................................................................................................................... 5
Spectroscopic Analyses to determine a ‘Fingerprint’ of life....................................................... 6
Recent Discoveries.......................................................................................................................... 7
Key Discoveries .......................................................................................................................... 7
51 Pegasi b............................................................................................................................... 7
Proxima Centuari b .................................................................................................................. 7
WASP-33b............................................................................................................................... 7
Proxima Centuari b and WASP-33b ........................................................................................... 7
Conclusions..................................................................................................................................... 9
References..................................................................................................................................... 10

3. Introduction
Humanity is evolving ever since the inception of the journey on earth. Learning new things and
discovering the unseen is in the roots of the evolution process. In the modern era, science doesn’t
believe that Sky is the limit rather it has expanded their span of research to the infinite space. Space
research has uncovered some mesmerising phenomenon which is lifting the human evolution to
the next level (Barge & Others, 2008).
Exoplanets
The curiosity to find earth-like planet can be dated to long time ago. But because of the incapability
of the available technologies, it was a dream to detect planets beyond our solar system. After the
time stated, the space research have taken a new leap and opened a new era of information. The
concept of Exoplanet born. It can also be referred to as Extra Solar Planet. Any planet which is not
within our solar system is Exoplanet. But an absolute definition is quite complex and problematic.
So some of the important characteristics of an Exoplanet is it has to be earth-like environment, it
can be giant or terrestrial type (Astronomy, 2017).
First Exoplanet: 51 Pegasi b
The first ever Exoplanet was discovered in October 1995 by Didier Queloz and Michel Mayor of
Geneva University. The planet was orbiting a star named 51 Pegasi and the planet was named after
it in a poetic way, 51 Pegasi b. The planet is 300 trillion miles away from our solar system. Actually
it is the inception point of Exoplanet chapter in space research. It is assumed that the surface
temperature of the planet is 1,000C and it is orbiting the sun in just 4 days. Because of its mass
and temperature, the Exoplanet is a “Hot Jupiter” kind of Exoplanet (Bbc.co.uk, 2017).
Total Exoplanets discovered
Since the discovery of 51 Pegasi b, thousands of new planets in different solar system has been
discovered. Till the date, a total of around 3,440 Exoplanets has been discovered. There are
different medium as well method through which the Exoplanets are confirmed. NASA’s Kepler is
one of the crucial in this case (Astronomy, 2017). Most of the planets are confirmed using transit
method. The table is given below –

4. Aim of the Report
The report is dedicated to provide a short description on the methods of discovering Exoplanets
and some of the recent and key discoveries in the Exoplanets using those methods

5. The methods of searching Exoplanets
Search for a habitable planet is quite a complex process and still we are far behind to be perfect in
searching for a suitable planet like earth. Today’s modern technologies doesn’t allow us to
perfectly identify an Exoplanet but there are some methods available for this purpose
The stars we are looking for
The priority at the time of looking for an Exoplanet is to find a habitable planet. The Exoplanetary
system should have a CHZ which is Circumstellar Habitable Zone. The zone must inhibit into a
stable star system. The probability of having CHZ will increase in such situation. The star system
should also have the presence of water (@JosephStromberg, 2017).
‘Super Earths’ and ‘Hot Jupiters’
There are a number of planets that can be considered at the time of the exploration of the space.
Hot Jupiters and Super Earths are most desired one. Hot Jupiters are referred to the exoplanets
which is similar to our solar system’s planet Jupiter in terms of mass but generally has short orbital
radii and a semi-major axes somewhere near .015 to .5 which can be converted to an astronomical
unit of .2×106 to 74.8×106 km. The word hot is added to the phenomenon because of the high
surface temperature of the planet (worldcrunch, 2017)
Super Earths refers to exoplanets which are much like earth with a higher mass. The term doesn’t
include any reference to the habitability of the planet, the surface condition or the environment. It
is total tagged with the mass of the earth (Exoplanetarchive.ipac.caltech.edu., 2017).
The concept of a “Habitable Zone”
The critical characteristics for “Habitable Zone” is the distance with the star so the liquid doesn’t
vaporize or freeze. Although the inception definitions were only concentrated on the thermal
equilibrium, the latest development also include the required gravitational pull caused by large
planets which allows it to generate essential energy for blooming life.
The techniques of detecting Exoplanets

6. As there are still some major limitations in the space research technologies, the advancements are
also praiseworthy. There are mainly three major techniques to detect Exoplanets. The focus of all
the techniques intertwined with its star. The major techniques are explained below –
The radial velocity method
Redial Velocity is one of the most useful methods in the exoplanetary research. This method focus
on the lights from the star and let it pass through a prism to split into spectrum. The spectrum is
then magnified which creates straight black lines on the usual colours. The spectral lines is parallel
to the wavelength of light which is originated from the star and absorbed the chemicals of the
planet. Every chemical has its own wavelength so is different from one another and can tell the
characteristics of the source. Studying these spectre lines is all we need to know about the planet
(European Space Agency., 2017).
The astrometry method
Other than spectre analysis, the exoplanet can also be detected by measuring the exact position of
a star. As a result the wobbling can be directly detected. Hubble space telescope is used for this
purpose (Wright & Others, 2011). But it is hard to accord these detections with the modern
methods. So, it is not possible to confirm the detections. Gaia is one the most perfect astrometric
satellite in the current data. The estimated data to processed using the satellite is around thousand
million stars. Once again, however, the wobbling motion caused by an Earth-sized planet will be
too small to be detectable, even by Gaia (AMNH., 2017).
The transit method
Another very promising method for detecting exoplanets is the transit method. In this method, the
major focus is on the fluctuation in the level of light due to the planet transiting through the star.
When a planet pass through a star, there is a subtle deviation in the emission of light of that sun.
For example, when Jupitar pass through, there is almost a 1 percent loss of light. This method has
gave us a total of 10 planets and is more promising method than others.
Other than these three major techniques, direct detection and imaging, Doppler isolation,
polarimetry, nulling interferometry, seeing more with space telescopes are also some of the other
popular techniques for detecting Exoplanets (Snellen & Others, 2010).

7. Spectroscopic Analyses to determine a ‘Fingerprint’ of life
According to Kreidberg & Others (2014) the fingerprint of life out in the space is detected using
the spectroscopic analysis. In this particular method, the light of the exoplanet is used. When we
try to determine whether the planet have an atmosphere or not, we analyse light that pass from the
atmosphere. When the light of a star pass through the atmosphere of a planet, substance of the
atmosphere absorb certain wavelength is a symbolic way. When we analyse the light of the planet,
it bears the signature of different chemical. If the spectroscopic analysis found that there is ample
amount of oxygen, water, CO2 and methane in the atmosphere, their might be a possibility of life
on that planet (Earth 2.0., 2017).

8. Recent Discoveries
In the infinite space, there are billions of planets and we have already discovered more than 2,000
planets. So, it is a little complex to narrow down these into a few planets. After considering a
number of factors, the key discoveries in the field are –
Key Discoveries
51 Pegasi b
The exoplanet journey was started from this point so 51 Pegasi b is one of the key discoveries. The
planet is categorised under the hot Jupiter and the distance with sun is roughly similar to Mercury
to sun. Because of the phenomenon, one side of the planet is always facing the sun (Wasp-
planets.net., 2017).
Proxima Centuari b
It has been officially confirmed that Proxima Century b, a red dwarf star, is only 4.25 light years
away from earth. The planet is confirmed using the Redial Velocity method in August, 2016. It is
slightly closer to the famous binary pair Alpha Centauri A and B. It has been estimated that the
mass is roughly 1.3 times that of earth (Gizmodo.com, 2017).
WASP-33b
This planet was discovered in 2011 and has a sort of "sunscreen" layer — a stratosphere — that
absorbs some of the visible and ultraviolet light from its parent star. Not only does this planet orbit
its star "backward," but it also triggers vibrations in the star, seen by the MOST satellite (WrightDr,
2013).
Proxima Centuari b and WASP-33b
It has been officially confirmed that Proxima Century b, a red dwarf star, is only 4.25 light years
away from earth. The planet is confirmed using the Redial Velocity method in August, 2016. It is
slightly closer to the famous binary pair Alpha Centauri A and B. It has been estimated that the
mass is roughly 1.3 times that of earth. It is within the habitable zone for exoplanet. The
environment is also habitable and water is in the liquid form (Mason, 2008). It’s not yet clear
whether this new exoplanet has an atmosphere. Because Proxima Centauri is a fairly active star,

9. Proxima b suffers x-ray fluxes approximately 400 times greater than what we experience here on
Earth, and this could cause any atmosphere to blow away.WASP-33 is a planet which is an
important contributors in the hot Jupiter category. The planet is very close to its star and the
temperature is quite off the chart. The planet is confirmed in 2010 using the transit method (Deleuil
& Others, 2008).

10. Conclusions
The essay is about the detection methods for the exoplanets and some recent important discoveries,
some of the important facts included in the essay. Moreover, there are some limitations in the
technology but the advancement in the sector quite praiseworthy. If science will excel in this rate,
we can hope that in the near future, we might be vising any nearby planet for the habitation
purpose. A lot of things has turned into reality from science fiction. Space research is that why an
exciting thing.

11. References
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