• Earth has two extra ‘moons’ – made entirely of dust and nine times wider than our planet, scientists have claimed.
• For more than 50 years their existence has been debated, but Hungarian researchers claim they now have enough evidence.
Important highlights of this observation
• Polish astronomer Kazimierz Kordylewski first spotted the dust ‘moons’ in 1961, and they became known as Kordylewski clouds.
• Orbiting Earth at a distance of 400,000 km, they are spread over an area nearly nine times the width of our planet – 105,000 km by 72,000 km.
• Despite their vast area, the Kordylewski clouds are composed of tiny dust particles that emit an extremely faint light.
• This makes them very hard to distinguish from the galactic light, sky glow and star light in the sky.
• The new study, first published in the Monthly Notices of the Royal Astronomical Society, used special polarising filters on cameras to prove the existence of the dust ‘moons’.
• The Hungarian scientists were able to track the scattered light coming from the reflection of the individual particles in the clouds.
• They also found the Kordylewski clouds constantly change in their composition.
• The dust particles inside them are swapped for others. Some are sucked away by the gravitational pulls from Earth or the Moon, while others come from meteor showers.
• Another key factor in the study is the location of the dust ‘moons’ at Lagrange points around Earth.
• These are gravitational ‘sweet spots’ in space where centrifugal forces are finely balanced, allowing objects to remain stationary.
Other important highlights
• In the 1950s, Kordylewski scoured two Lagrange points – L4 and L5 – where he saw glimpses of the two dust ‘moons’.
• Confirmation of their existence has consequences for future space missions.
• Satellites are sometimes parked at the Lagrange points to minimise their fuel consumption and remain in orbit.
• These reasons are why the giant James Webb Space Telescope will be based at the L2 point in 2020.
• Future Mars missions could also use Lagrange points as transfer stations.
• The discovery of the dust ‘moons’ will make space agencies especially interested in finding out if any more are waiting to be found.
Mains Paper 3: Science & Technology | Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology
Prelims level: Kordylewski clouds, Lagrange Points
Mains level: Various space missions and their objectives