Exoplanet: Chasing an Earth-Like Planet

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Rizal Technological University
Department of Earth and Space Science
BS Astronomy Technology

Exoplanet: chasing an
Earth-like planet

Submitted by:
Justine Guillerma C. Garcia
Ma. Christina Nunez
Pauline Grace R. Viñas

Submitted to: Professor Edna Aquino
Date submitted: December 18, 2012

Table of content:
Table of Contents
* What are exoplanets?
Definition of exoplanet
* Methods of detecting extrasolar planets
* What do we know about exoplanets?
* Number of Potential Habitable Worlds and exoplanets
* What was the First Extrasolar Planet Discovered?
* Visiting exoplanets
* Are exoplanet like the Earth?
* Is There Intelligent Life in the Universe
* Could we communicate with possible inhabitants? 
* Life in the Universe


There are many bases on how many exoplanets really are now. Different updates and numbers are state in different sources. Two of those sources are the NASA Planet Quest and the Planetary Habitability Laboratory. The NASA Planet Quest states that there are 2,321 candidates, 809 confirmed and an overall of 3,130 exoplanets. In addition, candidate exoplanets are those planets that astronomers have proven to a high degree of confidence, using multiple observations and, sometimes, two or more different instruments while confirmed exoplanets are those that come from the Kepler mission. And in order for each planet to be considered "confirmed", its existence has to be verified using other instruments, a process that takes time. However, Planetary Habitability Laboratory has different computation in the number of exoplanets. And the table below shows the information of the Number of Potential Habitable Worlds and the All Currently Known Exoplanets that was last updated in December 5, 2012.

Number of Potential Habitable Worlds|
Habitable Exoplanets| Unconfirmed Potential
Habitable Exoplanets (1)| Predicted Potential
Habitable Exomoons (2)| η Earth(3)|
7| 27| 30| 1.6%|
All Currently Known Exoplanets|
Confirmed Exoplanets (4)| NASA Kepler Candidates (5)| Other Unconfirmed Exoplanets (4)| 853| 2320| 180|

Take note of this:
(1) Base on NASA Kepler Mission, exoplanet candidates are waiting for confirmation. (2) Estimate based on the number of gas giant planets in the habitable zone with the right mass for a near Earth-size moon. (3) η Earth (Eta Earth) is the stellar frequency of potential habitable exoplanets based on observed values (this is a lower limit). (4) Confirmed and unconfirmed exoplanets are those listed by the Extrasolar Planets Encyclopedia plus any recent pending additions. (5) Most of NASA Kepler Candidates are unconfirmed exoplanets.

The earliest understanding of the solar system showed us that there were indeed other worlds in orbit about our Sun, and steadily growing understanding of their nature’s shows that all are dramatically different from Earth, and mostly very different from one another. However, on the other side exoplanet and the Earth have its own similarities. First, exoplanets resembles the Earth and it is spherical like the Earth. In general, planets are spherical due to the gravitational force. For example, if a planet had a very high mountain, it would be too heavy and would collapse under its own weight. So that is the reason why on Earth, there are no mountains higher than Mount Everest (8 km). Aside from that, they also similar when it comes in this characteristic, Earth and exoplanets do not shine. The planets of the Solar System are visible in the sky because they are illuminating by the Sun. From the Earth, we only see their illuminated parts. Even if the planets (and the moon) are spherical, we only see their phases from the Earth. Similarly, exoplanets are visible because they reflect the light from their host stars. As been said earlier, exoplanet are very different from one another and also have their own differences. Exoplanets do...
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