News outlets: Chicago Tribune, Pittsburgh Post-Gazette, The Star, Financial Times (gets a medal for spoiling the end with the first sentence), Otago Daily Times, The Age Oxygen is unusual in terms of its return to ground state: it can take 0.7 seconds to emit the 557.7nm green light and up to two minutes for the red 630.0nm emission. Collisions with other atoms or molecules absorb the excitation energy and prevent emission, this process is called collisional quenching. Because the highest parts of the atmosphere contain a higher percentage of oxygen and lower particle densities, such collisions are rare enough to allow time for oxygen to emit red light. Collisions become more frequent progressing down into the atmosphere due to increasing density, so that red emissions do not have time to happen, and eventually, even green light emissions are prevented. Green: At lower altitudes, the more frequent collisions suppress the 630nm (red) mode: rather the 557.7nm emission (green) dominates. A fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common. The excited molecular nitrogen (atomic nitrogen being rare due to the high stability of the N 2 molecule) plays a role here, as it can transfer energy by collision to an oxygen atom, which then radiates it away at the green wavelength. (Red and green can also mix together to produce pink or yellow hues.) The rapid decrease of concentration of atomic oxygen below about 100km is responsible for the abrupt-looking end of the lower edges of the curtains. Both the 557.7 and 630.0nm wavelengths correspond to forbidden transitions of atomic oxygen, a slow mechanism responsible for the graduality (0.7s and 107s respectively) of flaring and fading.

Størmer, Carl (1946). "Frequency of 12,330 measured heights of aurora from southern Norway in the years 1911–1944". Terrestrial Magnetism and Atmospheric Electricity. 51 (4): 501–504. Bibcode: 1946TeMAE..51..501S. doi: 10.1029/te051i004p00501. Boston operator (to Portland operator): "Please cut off your battery [power source] entirely for fifteen minutes." In 1778, Benjamin Franklin theorized in his paper Aurora Borealis, Suppositions and Conjectures towards forming an Hypothesis for its Explanation that an aurora was caused by a concentration of electrical charge in the polar regions intensified by the snow and moisture in the air: [88] [89] [90] Conjugate auroras are nearly exact mirror-image auroras found at conjugate points in the northern and southern hemispheres on the same geomagnetic field lines. These generally happen at the time of the equinoxes, when there is little difference in the orientation of the north and south geomagnetic poles to the sun. Attempts were made to image conjugate auroras by aircraft from Alaska and New Zealand in 1967, 1968, 1970, and 1971, with some success. [46] Causes [ edit ]

American Geophysical Union (20 August 2018). "New kind of aurora is not an aurora at all". Phys.org . Retrieved 21 August 2018. I dati personali non saranno oggetto di trasferimento né verso Paesi terzi non europei né verso organizzazioni internazionali. Devi, the ship's de facto chief engineer and leader, is concerned about the decaying infrastructure and biology of the ship: systems are breaking down, each generation has lower intelligence test scores than the last, and bacteria are mutating and evolving at a faster rate than humans. She tells the ship's AI, referred to simply as Ship, to keep a narrative of the voyage. After having some trouble with understanding the human concept of narrative, Ship eventually elects to follow the life of Devi's daughter Freya as a protagonist.

Crooker, N. U.; Feynman, J.; Gosling, J. T. (1 May 1977). "On the high correlation between long-term averages of solar wind speed and geomagnetic activity". Journal of Geophysical Research. 82 (13): 1933. Bibcode: 1977JGR....82.1933C. doi: 10.1029/JA082i013p01933. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere. Proton auroras are usually observed at lower latitudes. [52] Ionosphere [ edit ] As Archbishop of York, Stephen Cottrell, writes in his foreword to the book, Advent is not only a time for anticipating the moment Jesus Christ came into the world but also reflecting on the ‘last things’ foretold in the Book of Revelation where people of every tribe, tongue and nation rejoice before the throne of God. Phillips, J. L.; Stewart, A. I. F.; Luhmann, J. G. (1986). "The Venus ultraviolet aurora: Observations at 130.4 nm". Geophysical Research Letters. 13 (10): 1047–1050. Bibcode: 1986GeoRL..13.1047P. doi: 10.1029/GL013i010p01047. ISSN 1944-8007.

Novellas

Observations of the rhythmic movement of compass needles due to the influence of an aurora were confirmed in the Swedish city of Uppsala by Anders Celsius and Olof Hiorter. In 1741, Hiorter was able to link large magnetic fluctuations with an aurora being observed overhead. This evidence helped to support their theory that 'magnetic storms' are responsible for such compass fluctuations. [91] Church's 1865 painting Aurora Borealis