Earth’s moon may not be alone. After more than half a century of speculation and controversy, Hungarian astronomers and physicists say they have finally confirmed the existence of two Earth-orbiting “moons” entirely made of dust.
As they describe in the Monthly Notices of the Royal Astronomical Society, the team managed to capture snapshots of the mysterious clouds lurking just 250,000 miles away, roughly the same distance as the moon.
The presence of the dust ‘moons’ or Kordylewski clouds had been inferred by researchers since long before. But the first glimpse of the clouds was seen only in 1961 by Polish astronomer Kazimierz Kordylewski, after whom the dust clouds were named.
Facts about the newly discovered dust moons:
The new findings note that each Kordylewsky cloud is about 15 by 10 degrees wide, or equal to 30 by 20 lunar disks in the night sky.
They are spread over a space area that is almost nine times the width of Earth — about 65,000 by 45,000 miles in actual size.
The dust ‘moons’ are huge but they are made of tiny dust particles that barely measure one micrometer across.
When sunlight hits the dust particles, they glow very faintly, much like the zodiacal light we receive from the dust scattered in between planetary orbits.
Since these satellite dust clouds emit an extremely faint light, they are very difficult to find amidst the starlight, sky glow, galactic light and zodiacal light in the sky though they are as close to us as the moon.
The Kordylewski clouds are always changing. They might be stable in orbit and may have existed for millions of years, but the ingredients that make the clouds — the dust particles — are always getting swapped for others. Some escape to gravitational pulls from Earth or the moon, while others come from interplanetary spaces and meteor showers.
How Lagrange points in space helped find the extra ‘moons’?
Speculations about Earth having multiple moons have taken turns in astronomer circles for years. It was realized that if extra moons did exist, they could only do so in stable points in Earth’s orbit.
Lagrange points are sweet spots in a planetary orbit where the pull of gravity working from two opposing celestial bodies is balanced due to the centripetal force of their orbits. Thus, an object at a Lagrange point will remain fixed at a constant distance from both the moon and Earth.
In the 1950s, Kordylewski searched two Lagrange points — L4 and L5 — where he found the first glimpse of the two dust clouds orbiting Earth.
These huge clouds of dust could add much to space exploration efforts when it comes to fuel consumption and safety issues. Sometimes, satellites need to be parked at the Lagrange points so that the spacecraft consumes minimal fuel and can still stay in orbit
The James Webb Space Telescope will be set up at the L2 Lagrange point in 2020 for this purpose. Moreover, space agencies are also planning to use Lagrange points as transfer stations for Mars missions.