Today scientist are curiously interested to discover the planets orbiting other stars.So NASA started a mission (Kepler mission)
for finding the planets.No doubt that there is a large number of planets but the goal is to find the Earth like planets.
The mission is designed to survey our milky way galaxy and to find the planets orbiting other star in our galaxy.
Transit Method of Detecting Planets :
When a planet passes in front of a star,Then it is called 'transit'.
We have seen Venus and Mercury transits from the Earth.When a planet passes in front of a star then we see a black dot creeping across the sun . By using this method we can find other planets in galaxy. After finding the planet it's other properties like size, temperature can be measured.
Kepler Instrument is Used to find the Planet :
Kepler instrument is a .95 meter diameter telescope called a photometer.
this instrument will continuously monitor the brightness of more than 100,000 stars for the life of the mission - 3.5 years or more.