An exoplanet is a planet that orbits a star other than the Sun. Nearly 2000 exoplanets have been discovered orbiting other stars by detecting their gravitational influence or observing dimming of the star's light as the planet passes in front. The Kepler space telescope has been instrumental in discovering many new exoplanets using the transit method of detection, including some that may be capable of hosting life such as Gliese 581g. As exoplanet discoveries increase, interest in finding signs of life on other worlds outside our solar system continues to grow.

1. PRIMARY SCHOOL "VASIL APRILOV" - RUSE

2. An exoplanet or extrasolar planet is a planet that orbits
a star other than the Sun, a stellar remnant, or a brown
dwarf.
The discovery of exoplanets has intensified interest in the
search for extraterrestrial life, particularly for those that
orbit in the host star's habitable zone where it is possible
for liquid water (and therefore life) to exist on the surface.
The study of planetary habitability also considers a wide
range of other factors in determining the suitability of a
planet for hosting life.

4. Nearly 2000 exoplanets have been discovered
(1932 planets in 1222 planetary systems
including 484 multiple planetary systems as of
26 June 2015). There are also rogue planets,
which do not orbit any star and which tend to be
considered separately, especially if they are gas
giants, in which case they are often counted, like
WISE 0855−0714, as sub-brown dwarfs.

5. On 9 January 1992, radio
astronomers Aleksander
Wolszczan and Dale Frail
announced the discovery of two
planets orbiting the pulsar PSR
1257+12. This discovery was
confirmed, and is generally
considered to be the first
definitive detection of exoplanets.

6. On 6 October 1995, Michel Mayor and Didier Queloz of the
University of Geneva announced the first definitive detection of
an exoplanet orbiting a main-sequence star, namely the
nearby G-type star 51 Pegasi. This discovery, made at the
Observatoire de Haute-Provence, ushered in the modern era of
exoplanetary discovery. Technological advances, most notably in
high-resolution spectroscopy, led to the rapid detection of many
new exoplanets: astronomers could detect exoplanets indirectly
by measuring their gravitational influence on the motion of their
host stars. More extrasolar planets were later detected by
observing the variation in a star's apparent luminosity as an
orbiting planet passed in front of it.

7. Radial velocity
Transit
Timing
Direct imaging
Microlensing
Number of extrasolar planet discoveries per year through
September 2014, with colors indicating method of detection:

8. When a planet passes in front of a star
as viewed from Earth, the event is called
a “transit”. On Earth, we can observe an
occasional Venus or Mercury transit.
These events are seen as a small black
dot creeping across the Sun—Venus or
Mercury blocks sunlight as the planet
moves between the Sun and us. Kepler
finds planets by looking for tiny dips in
the brightness of a star when a planet
crosses in front of it—we say the planet
transits the star.
The Transit Method of Detecting Extrasolar Planets

9. Once detected, the planet's orbital size can be
calculated from the period (how long it takes the
planet to orbit once around the star) and the mass of
the star using Kepler's Third Law of planetary motion.
The size of the planet is found from the depth of the
transit (how much the brightness of the star drops)
and the size of the star. From the orbital size and the
temperature of the star, the planet's characteristic
temperature can be calculated. From this the question
of whether or not the planet is habitable (not
necessarily inhabited) can be answered.

10. On March 7, 2009 NASA launched KEPLER space
observatory to discover Earth-like planets orbiting other
stars.
Kepler uses a transit
method to determine
planets orbiting other
stars.

12. New data suggests the confirmation of the exoplanet Gliese
581g and the best candidate so far of a potential habitable
exoplanet. The nearby star Gliese 581 is well known for having
four planets with the outermost planet, Gliese 581d, already
suspected habitable. This will be the first time evidence for any
two potential habitable exoplanets orbiting the same star.
Gliese 581g will be included, together with Gliese 667Cc,
Kepler-22b, HD85512, and Gliese 581d, in the Habitable
Exoplanets Catalog of the PHL @ UPR Arecibo as the best
five objects of interest for Earth-like exoplanets.

14. On 9 May 2013, a congressional hearing by two
United States House of Representatives
subcommittees discussed "Exoplanet Discoveries:
Have We Found Other Earths?", prompted by the
discovery of exoplanet Kepler-62f, along with
Kepler-62e and Kepler-62c. A related special issue
of the journal Science, published earlier, described
the discovery of the exoplanets.

15. WE START WITH INTERNET
RESEARCH

16. EXOPLANETS AND OUTER SPACE

17. The Exoplanets in our Imagination:

18. Models of Exoplanets:

19. https://en.wikipedia.org/wiki/Kepler_%28spacecraft%29
http://phl.upr.edu/press-releases/fivepotentialhabitableexoplanetsnow
https://en.wikipedia.org/wiki/Exoplanet
http://www.nasa.gov/mission_pages/kepler/overview/index.html