News: Recently, scientists for the first time have spotted a Moon-Forming Region around a planet beyond our solar system (Exoplanet).
What are Exoplanets?
- More than 4,400 planets have been discovered outside our solar system, called exoplanets.
- Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star. No circumplanetary discs had been found until now because all the known exoplanets resided in “mature” – fully developed – solar systems, except the two infant gas planets orbiting PDS 70.
- Scientists detected a disc of swirling material accumulating around two exoplanets seen orbiting a young star called PDS 70. PDS 70 is located a relatively close 370 light years from Earth.
- A light year is the distance light travels in a year, about 9.5 trillion km.
- It is called a circumplanetary disc, and it is from these those moons are born. The disc around PDS 70c (The Exoplanet), with a diameter about equal to the distance of the Earth to the sun, possesses enough mass to produce up to three moons the size of Earth’s moon. PDS 70c orbits its star at 33 times the distance of the Earth from the sun, similar to the planet Neptune in our solar system.
- The orange-coloured star PDS 70, roughly the same mass as our Sun, is about 5 million years old. The two planets are even younger. Both planets are similar (although larger) to Jupiter, a gas giant.
- It was around one of the two planets, called PDS 70c, that a moon-forming disc was observed. Both planets are still in their youth and are at a dynamic stage in which they are still acquiring their atmospheres.
Birth of Moon:
- Stars burst to life within clouds of interstellar gas and dust scattered throughout galaxies.
- Leftover material spinning around a new star then coalesces into planets, and circumplanetary discs surrounding some planets similarly yield moons.
- The dominant mechanism thought to underpin planet formation is called “core accretion”.
- In this scenario, small dust grains, coated in ice, gradually grow to larger and larger sizes through successive collisions with other grains.
- This continues until the grains have grown to a size of a planetary core, at which point the young planet has a strong enough gravitational potential to accrete gas which will form its atmosphere.
- Some nascent planets attract a disc of material around them, with the same process that gives rise to planets around a star leading to the formation of moons around planets.
- The disc around PDS 70c, with a diameter about equal to the distance of the Earth to the sun, possesses enough mass to produce up to three moons the size of Earth’s moon.