Everyone is familiar with the Moon; it is a big object revolving around the Earth. The other planets also have moons orbiting around them, some with more than one. So what if were to tell you now that the Earth has three “Moons”? Hard to believe, right? Well, a group of Hungarian scientists has confirmed just this long-standing astronomical speculation.
So, what are these new “Moons”? Technically, they are not moons but natural satellites of Earth. Also unlike “The Moon”, the two newly confirmed satellites are actually Dust Clouds, that is, huge clouds of dust floating in space around Earth. These are called Kordylewski clouds, named after the Polish astronomer Kazimierz Kordylewski who first speculated the existence of natural bodies at the Lagrange points of Earth, way back in the 1950s. The existence of these bodies was hotly debated until recently, when Hungarian astronomers and physicists finally provided enough data to confirm that our Moon has at least two other companions – made entirely of dust.
Let’s start with Lagrange points, which are very important in astronomy (And for these new moons to exist). A Lagrange point is a location in space where the combined gravitational forces of two large bodies, such as Earth and the Sun or Earth and the Moon, equal the centrifugal force felt by a much smaller third body. There are 5 such points, namely L1, L2, L3, L4 and L5.
These Lagrange points are very interesting as well as useful as far as space exploration is concerned. For example, the James Webb space telescope, yet to be launched will be placed at L2. So, sometimes these spots are also called as “Parking spots in Space.”
Returning to our “Moons”, when Kordylewski searched L4 and L5 in the 1950s, he found the first glimpses of two dust clouds orbit the Earth. In this case, the Lagrange points are with respect to the Earth-Moon system (The photo shows the points for Earth-Sun system). And in 1961, he succeeded in photographing two bright patches near L5. In October 2018, the existence of the Kordylewski clouds was reported to have been confirmed, even though, earlier, in 1992, the Japanese Hiten space probe, which passed through the Lagrangian points to detect trapped dust particles, found something. Sorry, actually, it did “not find” an obvious increase in dust levels above the density in surrounding space.
Here are some facts about our newly found neighbours:
• The new findings note that each Kordylewski cloud is about 15 by 10 degrees wide, or equal to 30 by 20 lunar disks in the night sky, in other words, they look 20-30 times wider than the Moon from Earth.
• 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 micrometre 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 star light, sky glow, galactic light and zodiacal light in the sky though they are as close to us as the moon.
• The recent study revealing the existence of the two dust ‘moons’ used special polarizing filters on cameras to reveal the scattered light coming from the reflection of the individual dust particles in the clouds.
Many might be thinking, “What is special in this? It is not going to affect my life. Why should I care about this?”. This is partly true (unless we have some Martians living out there, to whom we can brag that we have 3 moons, more than their 2 moons), but if we consider the fact that something is discovered at the Lagrange points, it fuels the fact that more objects can be discovered at other such points. For example, people have been speculating that another Earth like object is at L3 w.r.t Sun-Earth system, which is hidden by the sun. Who knows this might be true, making life possible there too. The most fascinating thing is that, even after 60 plus years since the first satellite, Sputnik 1, was launched, the final frontier for human life continues to throw something new at us. Only God knows what and how much is left to be discovered by us.