A second orbital plane? A team of Japanese scientists has discovered that the solar system has a hitherto unknown second alignment plane and that in no case does it coincide with the ecliptic, that is, the plane on which planets such as Earth rest and which is believed to be a remnant of how the solar system formed: a flat disk of dust that revolves around the Sun and groups together asteroids, planets, and other objects. The reason is that as the solar system formed, it did so as this kind of flat disk that revolved around a bulge that eventually became the Sun.
Viewed from Earth, the Sun, Moon, and planets appear to move along the ecliptic. But why is this not the case with comets? The plane of their orbits need not be close to the ecliptic.
It is not the only important alignment of the solar system
Higuchi studied the effects of galactic gravity on long-period comet analytical investigation of the equations governing orbital motion. By tracking the point where long-period comets are farthest from the Sun and moving out of this plane, Arika Higuchi, assistant professor at Japan University of Occupational and Environmental Health and leader of the work publishing The Astronomical Journal , has shown that there may be a second “empty ecliptic” alignment plane.
Some of these comets appear to line up in a different orbital plane rotated 180 degrees with respect to the galactic pole, which could help us understand how comets originally formed in our solar system.
When considering galactic gravity, the aphelion (the farthest point in a planet’s orbit around the Sun) of long-period comets clusters around two planes:
- Ecliptic (which is inclined relative to the disk of the Milky Way about 60 degrees)
- Empty Ecliptic (which is also tilted 60 degrees but in the opposite direction)
Why call it ’empty’?
Based on the mathematical nomenclature and because initially, it does not contain objects ; later it was populated with scattered comets, a product of billions of years, a product of the galactic tide, that is, the gravitational field of the galaxy itself.
This hypothesis was later confirmed by Higuchi by cross-checking his findings with calculations by the PC Cluster at NAOJ’s Center for Computational Astrophysics, and analysis of comets in NASA’s JPL Small Body database, which showed peaks in the ecliptic and empty ecliptic. The aphelion distribution had two distinct peaks: near the ecliptic and the empty ecliptic. However, Higuchi doesn’t think we have to take these results as conclusive. “The peaks are not exactly in the planes of the ecliptic or the empty ecliptic, but close to them”, clarifies the astronomer.
“Detailed examination of the long-period comet distribution will be our future work. The whole-sky scanning project known as the Legacy Survey of Space and Time (LSST) will provide valuable information for this study,” concludes Higuchi.
Referencia: Arika Higuchi. Anisotropy of Long-period Comets Explained by Their Formation Process, The Astronomical Journal (2020). DOI: 10.3847/1538-3881/aba94d
