How are new planets discovered?
In solar system planets were discovered by observation and gravity calculations.
Planets in other stars are found by 3 different methods.
1 direct observation or photography
2 Wobbling of central star due to elliptical,orbit of huge planets and pull of gravity.
3 transit method.When planet come s in front of a star a small dip,i n its light observed,..From the drop ,in light and period the size and period of planet can be calculated.