The Solar System formed 4. 6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system’s mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
Dr. Jason Soderblom said in a September 10, 2015 Massachusetts Institute of Technology (MIT) Press Release that the evolution of lunar porosity can provide scientists with valuable clues to some of the most ancient life-supporting processes occurring in our Solar System. Dr. Soderblom is a planetary research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences in Cambridge, Massachusetts.
However, the astronomers will require more HST observations in order to obtain accurate measurements in order to determine if the moon's orbit is circular or elliptical. Preliminary estimates suggest that if the moon is in a circular orbit, it finishes a circle around Makemake in 12 days or longer.
"We are just beginning to try and figure out quantitatively how all this might smooth a surface," Dr. Thomas said in the May 17, 2013 New Scientist.