Quick pop quiz : how many moons does the Earth have ? If you said one , you are correct – but Earthoccasionallypicks upquasi - Moon , which are not gravitationally bind to our major planet but share our sphere for a time and are influenced by our gravitational attraction during their orbit around the Sun .
But as well as a unconstipated Sun Myung Moon and the rum quasi - moon , Earth also has spectre moons . To understand these so - called " synodic month " – also term Kordylewski cloud – you postulate to acquire about Lagrange Points , but as luck would have it these are fairly coolheaded too .
" Lagrange Points are position in blank space where the gravitational forces of a two - body organisation like the Sun and Earth produce enhanced neighborhood of attraction and repulsion,“NASA explains . " These can be used by spacecraft as ' parking spots ' in blank space to stay in a fixed position with minimal fuel phthisis . "
There are five Lagrange points, but not all of them are stable.Image credit: NASA.
These regions are not all stable , though even the unstable regions can establish useful .
" Of the five Lagrange breaker point , three are unsound and two are stable . The unstable Lagrange points – labeled L1 , L2 , and L3 – lie in along the line connecting the two with child masses , " NASA keep on . " The stable Lagrange point – label L4 and L5 – form the apex of two equilateral triangles that have the large mass at their vertices . L4 leads the orbit of earth and L5 follows . "
This is n’t an abstract estimate , but something we habituate in praxis . The JWST is placed in the L2 Lagrange point , while the L1 point is used for the Solar and Heliospheric Observatory Satellite , for its continuous position of our star .
pocket-sized body are often found in these unchanging Lagrange points , with the obvious example being trojan asteroids obtain in the L4 and L5 point between Jupiter and the Sun .
Lagrange point also take place within the Earth - Moon system , with L4 and L5 also being stable . Though they do n’t contain any smaller body ( that we know of ) , astronomers have been searching for " specter Moon " in the regionssince the 1960s , which are accumulation of junk in the region .
This is not an easy task , as the dust is unmanageable to detect against the backdrop of skyglow , starlight , zodiacal light , and light from the Milky Way , so it ’s no surprisal that we did n’t find foretoken of one for a while . They were tentatively reported by Kazimierz Kordylewski , who kick in the cloud one of their figure . But the Japanese Hiten place investigation , whichlaunched in 1990 , did not find any obvious signs of an increase in dust as it lead through the L4 and L5 points between the Earth and the Moon , have discovery seem improbable .
However , in 2018 , one squad attempted to simulate Kordylewski cloud to see how they might advantageously be detected . The squad prefer to use polarizing filters , which allow through only polarized visible radiation , know that reflected or scattered light isusually polarise . When they look for the spectre moons at the L5 full point , they find light that had been polarized by detritus , while the squad rein out other sources of polarization base on thedirection of polarization .
" For the first sentence we have watch over and register polarimetrically the [ Kordylewski clouds ] around the Lagrange point L5 of the Earth and Moon , " the team wrote in theirpaper . " By this we bear out the being of the KDC first observed photometrically by Kordylewski . "
" The [ cloud ] may be a transitory phenomenon , " they added , " because the L4 and L5 points might be unstable due to perturbations of the Sun , solar wind , and other planets , as many astronomers believe . "
The newspaper is published in theMonthly Notices of the Royal Astronomical Society .
Correction : An earlier version of this article incorrectly stated that the L2 Lagrange point is between the Earth and the Sun .
