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A group of Hungarian scientists has confirmed a long-standing astronomical speculation: the Earth has three natural satellites or moons, not one.
The research, published in the Monthly Notices of the Royal Astronomical Society, says that the new moons are entirely made up of extremely tiny dust particles less than one millimetre size and reflect light rather faintly. This is why they were difficult to observe and study in the first place even when they are located at around the same distance as the Moon from the Earth—400,000 kilometres. “It is very difficult to detect the clouds against the galactic light, star light, zodiacal light, and sky glow,” coauthor of the paper Gábor Horváth, a physicist at Eötvös Loránd University, told the media.
In 1961, Kazimierz Kordylewski, a Polish scientist had observed these moons for the first time and they were later named after him as Kordylewski Dust Clouds (KDCs). But their existence has been questioned by astronomers for the past six decades and not many accurate models or simulations of these objects are available.
In the current study, Horváth and his group used special filters on their cameras which polarise incoming light to catch hold of and study the scattered light from the dust particles inside these moons. With this collected data, the astronomers were able to establish that the KDCs are spread across an expanse of 1,00,000 km by 70,000 km in space. This is equivalent to 30 by 20 lunar disks.
Though the dust clouds themselves are ancient, the particles they comprise of change and are replaced over time. They take in dust from various sources—remnants of planets, comets, meteors, asteroids and other objects loitering around in space. When the Earth, the Sun or the Moon destabilise, the particles slip away with their gravity, and particles from other sources replace them.
Kordylewski had discovered the dust clouds close to a special point in space known as L5, which is a Lagrange point of the Earth-Moon gravitational system. Lagrange points are places of equilibrium in space where gravitational forces of two large and solid astronomical objects like the Earth and the Moon cancel out the centrifugal forces. Many other small celestial objects are often found around Lagrange points.
For example, there are minor planets close to the Lagrange points of the Sun-Earth gravitational system and the Sun-Jupiter system. Such points are also ideal for parking satellites and other space vehicles as the fuel consumption is considerably lower here. They will be essential for space exploration projects as transfer stations where space shuttles and stations can stop over on long journeys to other planets and even the Sun. There are five such points of stability identified in any such two-body system including the Earth-Moon system.
This article was originally published on Down to Earth.
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