Context: Recently, a team of researchers led by the Max Planck Institute for Solar System Research in Göttingen discovered an exoplanet KOI-456.04, which is less than twice the size of the Earth and orbits a sun-like star.
About KOI-456.04 planet

• The similarities between this distant planet – named KOI-456.04 – and Earth are numerous, and researchers hope it could mean that the conditions there might be right for life. The observation was made by the Max Planck Institute for Solar System Research in Göttingen, Germany.
• The Max Planck Society describes the star and its planet as a “mirror image” of the Earth and the Sun. They’re around 3,000 light-years away from Earth.
• So far, scientists around the world have managed to spot over 4,000 exoplanets – that is, planets that exist outside of the solar system – the Max Planck Society said.
• Scientists are usually interested to find planets that are similar to Earth, because this gives rise to the possibility that life might exist there.
• To start with, KOI-456.04 orbits a star that is similar to the Sun. For one thing, this star – called Kepler-160 – actually emits plenty of visible light, which is something that most exoplanets’ stars don’t do.

Scientists noted many similarities between the planet and star and the Earth and the Sun.

• Kepler-160 is also very close to the Sun’s size – its radius is just 10 percent larger – and its surface temperature just 300 degrees cooler; next to nothing in astrophysical terms.
• This is significant because most stars of exoplanets tend to be small and dim and mostly emit infrared radiation – belonging to the ‘red dwarf’ classification of stars.
• This is a problem as far as life is concerned. Many red dwarfs are thought to emit radiation that fries any planets that get too close.
• But since red dwarfs are cool and dim compared to the Sun, planets need to be relatively close in order to receive the amount of warmth that scientists think could lead to life.

About Exoplanet

• These are planets outside the solar system and are super earths – sizes ranging between Earth and Neptune.
• They may be gas giants or planets with solid landmass.
• Exoplanets are identified using four methods – the transit method, wobble method, microlensing and direct imaging.
• Transit method: Kepler Mission, Spitzer Space Telescope and TRAnsiting Planets and Planetesimals Small Telescope uses this method. When an exoplanet passes in front of its star, the light of the start dims for a fraction of a second. This dip in starlight reveals the presence and movement of an exoplanet.
• Wobble Method: In this method Doppler Spectroscopy is used. A common centre of mass is formed when a star and an exoplanet moves around. If the mass of the exoplanet is greater than its star there occurs a wobble in the centre of mass which is detected as a shift in stat light frequency.
• Direct Imaging: This method is used on star systems that are close to the earth. It is a limited method. Using an instrument called Coronagraph, scientists take the image of the star system. It will block the light of the star and will reveal the dim light on the planets.
• Microlensing: This method will reveal exoplanets that absorbs all of its starlight and appears dark. Objects in space curve the space-time and bend the light traveling near it. This is known as microlensing.