Sumbluddy Idiuts useless bunch of facts for the day: You may have noticed last night was a Full Moon, so heres a few facts and figures on that giant cheese ball in the sky... just in case you were wondering. #1) 300,000 = The number of impact craters larger than 1 km in diameter on the near side of the Moon alone, showing just how violent our astronomical neighbourhoods history has been. #2) 4,624 = Distance in km above the Earths core (in the direction of the moon) where the Earth and Moon both actually orbit their mutual centre of mass, called the barycentre. This is actually closer to our planets surface than its core.. about 1,700km below ground). All significantly gravitationally bound bodies orbit this point (their mutual barycentre) between their respective centres of mass, whether in binary or multi-body systems.. And for much larger dominating participants in such dances, the relatively small orbital distance compared to their partners can be so small the movement is quite difficult to detect or may appear as just a slight wobble... Much like the wobble of a hammer thrower winding up to fling the swinging weight. Our solar system, galaxy, local galaxy cluster and likely the universe as a whole all have these centres of mass being orbited by all of their constituents, including us. #3) 1 = Side of the Moon thats only ever visible from Earth. (Rather the same specific area of its surface is). Technically speaking, all spheres have only one side, and old Moon being as-near-as-makes-no-difference a sphere, this ones redundant from the get-go.... But, for the benefit of better understanding, and to honour a particular ground-breaking album from decades past, we can overlook that little fact and focus on another for now. The Moon, being quite large in relation the Earth, is in a tidally locked orbit, known as synchronous rotation. This means that it spins one complete revolution in the same time and direction it completes one orbit of the Earth-Moon barycentre, resulting in the same area of the Lunar surface locked always facing us. Because of this, the side opposite Earth is often called The Dark Side, as it never faces Earth, although the entire surface gets its time in the Sun as our natural satellite slowly circles our planet. #4) 3,600 = Speed in km/h at which the Moon circles the Earth, called its orbital velocity. Both the Earth and Moon together orbit the Sun at over 100,000 km/h, with our whole solar system orbiting the Milky Way Galaxys barycentre (the Supermassive Black Hole, named Sagittarius A* [Sag A Star] that occupies the centre of our galaxy and gravitationally dominates every other occupant of it with its tremendous mass of several billion times that of our Sun), at speeds many times faster even than that. #5) 27 = Comparitive size of the Moon given as a percentage of that of the Earth, giving it a diameter of 3,474.2 km, compared to 12,750 for Earth. #6) 60 = Density of the Moon related to Earth given as a percentage of Earth density. This discrepancy can be explained when one notes that the Moon was almost certainly formed from crustal material (less dense rock) blasted off into space in a planet shattering collision between the newly formed Proto-Earth and a Mars sized planet (known as Theia) around 4 billion years ago. (The early solar system was a much more crowded, violent, inhospitable place). As the two molten proto-planets (young, still forming planetary bodies) collided, both iron cores (being heavier than the surrounding rock) sunk into the centre of the new, larger Earth, as predominantly lighter materials ejected by the impact swung into orbit around the Earth and slowly spun into a disk which eventually accreted into what would from then on be the planets faithful follower and protector. Very little iron (in the grand scheme of things) made it into Earth orbit and was therefore available for the Moons formation, resulting in a relatively much smaller Lunar iron core that accounts for the difference in overall density of the two bodies. #7) 50,300 = The number of km closer then farther away from Earth the Moon can wander each fortnight, from the closest (perihelion) to the most distant (aphelion) points in its variable, elliptical, near-month-long orbit. Its distance from (technically altitude above the equatorial surface of) Earth ranges from 356,400 to 406,700km at the orbital extremities, though variations are rarely so pronounced. #8) 2,240 = Diameter in km of the largest known impact crater in the solar system, the South Pole-Aitken Basin, situated on the Moons Earth-opposing hemisphere. The continent sized, 13 km deep crater is obvious evidence of an almost unimaginable cataclysm that could well have devastated Earth and demolished any early life it may have inhabited, had our little bodyguard not taken the blow. There is a very plausible theory that as the Moon was forming from the debris blasted into the space around our infant planet by the Earth-Theia collision described above in fact #6, more than just the one sizable satellite started forming. The largest was the Moon, and its likely that at least one other rather large (yet significantly smaller) body was born from the same accretion disk of Earth-circling rock, into the same orbit, and eventually collided with its larger sibling, leaving the Moon scarred for life and the other obliterated. #9) 1/81 = The Moons comparative mass, expressed as a fraction of the mass of Earth. Expressed as a whole number, the Moons overall mass is 73,477,000,000,000,000,000 (73.477 quintillion) tonnes. Though the Earth is roughly only four times the size of its Moon, our planet is 81 times as massive (heavy). Do the maths if you like, just remember to include ALL the zeros! #10) -247 = Temperature in degrees Celsius measured in the Moons north polar Hermite Crater. This is the lowest temperature ever recorded in our solar system by any spacecraft, colder even than the surface of Pluto. At barely 27°C above absolute zero, this is around 230°C colder than your standard food freezer. #11) 15 = Length of time in microseconds (millionths of a second) that the length of one day on Earth grows by every year due to the tidal effect of the Earth spinning much faster than the Moon orbits it. The slower moving Moon pulls back on the faster rotating Earth, which slows Earths rotation and speeds up the Moons orbital velocity, which in turn pushes the Moon out to an overall slightly more distant orbit in order to be abiding by the law of conservation of angular momentum (38 mm per year is added to the radius of the Moons average orbital distance). Over the last 4 billion years this effect has slowed Earths rotation from its original 16 hour day to the current 24 hour day were familiar with. The Moon also now orbits many times farther from Earth than it did when it formed, and this trend will continue indefinitely, until the Sun eventually destroys both Earth and Moon in 4-5 billion years. #12) 12 = The number of native Earthlings ever privileged enough to have made the epic journey to step foot on the Moons surface....So far..... (Dont argue. It really happened. The proof is irrefutable.) #13) 13 = The amount of months a year really SHOULD (still) contain. The word Month is not surprisingly derived from the word Moon (as is the word Monday), and actually originally represented one 28 day lunar orbit of Earth. 13 of these 28 day months add up to one 364 day year which is far simpler than the Julian 12 month calendar we follow today. It would still require occasional leap days to catch up to the 365.25 day year that our planet takes to complete one full orbit of the sun, or more specifically the Earth/sun barycentre. 5 days would need to be caught up every 4 years to account for the 1.25 days left behind each year, but this is still less complicated than the dozen 28, 29, 30 and 31 day months we have now. It was certainly the preferred choice for marking the passage of time for the vast majority of ancient sky-gazing civilisations, as is apparent in historic calendars, monuments stories and artwork from around the world. Each 28 day month was quartered into four seven day-weeks, which as you know still prevail to this day despite centuries of the chronological carnage carried out to create intentionally induced confusion and human disassociation with nature. This 13 month x 28 day system is known as natural time, and it should be a goal of humanity to return to this mindset of time if we care to really be conscious and appreciate our place in the cosmos, and live a healthy, balanced existence. #14) 173 = Total number of Moons orbiting the eight planets in our solar system (or rather the total number of natural satellites of planets in our solar system, as they are actually defined), plus at least another eight orbiting dwarf planets (such as Plutos satellite Charon), with at least 76 objects in the Asteroid Belt having natural satellites of their own. The Moon is the only the official name for Earths natural satellite, and nearly all of the others have names of their own. The Moon is the largest natural satellite of a planet in our solar system relative to the size of its host planet, and the closest planetary satellite to the Sun. Although Mercury and Venus both lack Moons of their own, and Earth only has one, the other five planets all have more than one, from Mars with two, to Jupiters 67. Most of these are remarkably different, in almost every conceivable way, and a few even seem to be possible candidates for finding life outside of Earths atmosphere. #15) 4, 7, 14, 28 - Astrophysics, Mathematics and Biology = 14 nights (and the accompanying days), or one fortnight, is half of one 28 day lunar cycle, so a month is obviously four seven day weeks. Interestingly enough the 28 day lunar cycle is the precise time scale which humans have evolved for the female menstrual cycle to exactly coincide with. Human biology actually follows mathematical, astronomical patterns, Lastly... The Moon plays a far, far greater role than just pulling water across our planet to provide tides, lighting up dark nights, and bringing out the crazies when it appears full. Its influence not just on our planet, but on human biology, physiology, and our way of life throughout history is absolutely remarkable. Its presence undoubtedly provided the protection and stability Earth required to allow life to not only exist in the first place, but to thrive and flourish with such complexity and diversity, which ultimately led to the evolutionary path which eventuated to the existence of us. So next time you look up at the Moon, spare a little thought for just how important it is to our lives, and be humbled by the knowledge of just how it came to be, floating up there above our heads in its perpetual journey.
Posted on: Sat, 15 Feb 2014 12:48:01 +0000