Solar Systems Cheat Sheet (DRAFT) by rajiabraham

1. Crater formation starts with the impactor reaching the ground with a velocity of tens of kilometres per second. 2. The impactor penetrates into the surface by one or two diameters, compre­ssing the rock ahead of it, before its momentum is lost. (milli­sec­onds) 3. A very high pressure shock wave moves outwards, compre­ssing the rock to very high pressures. (~seconds) 4. With the energy released, and the impactor completely vaporised, the rock around the impact site expands again, blowing vast amounts of debris out of the area in a spherical crater as the shock wave reflects backwards. (secon­ds-­min­utes) 5. Over longer time scales, re-exp­ansion of the rock continues (sometimes lifting up a central peak), and the crater walls collapse, forming a larger, shallower crater. (minut­es-­hours) 6. Over geological time scales, erosion and sediment blur or bury craters. 


Diverting the orbit of an object is techni­cally possible, if we can predict a collision years or decades in advance. • For strong, solid objects (solid rock or metal), nuclear explosions could vaporise asteroid material and slightly alter the orbit, a few metres­/second for every Megaton of explosion. • Rockets could be attached to the surface of an asteroid to push it, but thrusts would be very low. • Much harder for ‘rubble piles’: loosely bound collec­tions of rocks, like ‘Mathilde’ – they would just disperse slightly, then clump back together under their own gravity. • Even if you could break up and disperse an object, it would be worse than doing nothing – it would spread the effects over a larger area. • Divers­ion­ise­sse­nti­all­yim­pos­sib­lef­orn­ewl­yfo­und­comets: much higher veloci­ties, very weak material, and less warning time (weeks to months).

1. Gudjyt The sky the firmament 2. Kangal The east; or, more properly, the spot of sun-ri­sing, as it varies throughout the year. 3. Nganga the Sun. The Sun is a female, and the Moon is a male. They say the Daran, or eastern men, see where the Sun rises out of the water; where the water and the sky meet together. (cf. ngangan = mother) 4. Djaat the Sun (KGS) 5. Julagoling Name of the planet Venus. She is described as a very pretty young woman, powerful in witchc­raft. Manilyen Jupiter (KGS) 6. Binnar A meteor, described by the natives as a star of fire ; seldom visible, but when seen considered by them as an omen of death.

1. Ngangar the stars 2. Godoitch One of the conste­lla­tions. 3. Wul-la­jerang The Pleiades 4.Bulgut A star, the wife of Tdadam 5. Dedam A name given to two stars, one male, the other female, of which the following story is told. Dedam the man speared Dedam the woman, because she let his brother's two children stray away. The children are repres­ented by two small stars at some distance higher in the heavens. The spear is repres­ented by two stars standing one on each side of the woman's body. 6. Wurdoitch or Wurdytch The name of a star, supposed to have been a native. 7. Djingun A star; one of the wives of Wurdytch 8.Other star names Jindang, Bwolluk, Muninj­ing­erang, Narragara, Wurjallak

1. Maik The moon. The moon is a male, and the sun a female. Also miga, miki 2. Mikang Moonlight Moon Waxing: 1. Werberang warri New moon 2. Marong­orong First quarter 3. Bangal Half-moon 4. Kabbul Second quarter 5. Gerradil katti Full moon Moon Waning: 1. Bina bardok 2. Burno wandat Three quarters 3. Jidik golang Half-moon 4. Narrat Last quarter Seasons: 1. Makuru June and July 2. Djilba August and September 3. Kambarang October and November. 4. Birak December and January 5. Bunuru February and March 6. Wan-yarang, or Djeran April and May.

Aristotle, utilising Pythag­oras’ deductive reasoning, put forward the first convincing argument for a spherical Earth by observing the lunar eclipse • He also argued for geocen­tricism (the Earth at the centre of the Universe). Ptolemy (incor­rectly) argued the Earth was stationary at the centre of the Universe and the celestial bodies orbit it in perfect circles in uniform circular motion • Ptolemy’s geocentric model required the insertion of epicycles and other mathem­atical comple­xities to explain the observed retrograde motion of the celestial bodies