Possible 6,000 Year Old Summer Solstice, Midnight Backlighting of Mount Denali as seen from Anchorage Alaska

(anticipated full release, summer 2016)

The region surrounding Anchorage Alaska is understood by researchers to have been occupied by humans for the better part of 6,000 years.^[1] This area of Alaska situated along the upper tip of Cook Inlet, near the vicinity of the Kink Arm intersection, extending north between the Yentna River along the western boundary and Susitna River along the eastern boundary having a fairly smooth geographic topography, void of major hills and or mountains to interfere with views towards the North North West.^[2]

This direction being in direct line of sight of the geologically pronounce Mount McKinley massif nearly 135 miles (217 km) away from Anchorage.^[3] The massif being composed of the following principle peaks as seen from Anchorage, Mount Denali (Mt. McKinley) 20,237' ft (6,168 m) the near equally distant Mount Begguya (Mt. Hunter) 14,573' ft (4,442 m) and Mount Foraker 17,400' ft (5,304 m) along the south east flank of Mt. Denali (Fig. 1).^[4] An individual in this region of south central Alaska, on clear days being provided with an expansive view of these distant mountains, and one of the longest viewable terrestrial baseline path in North America, if not the longest, easily extending another 100 miles (160 km) past Anchorage.

The baseline being so great in length, the clear line of sight along the downhill sloping terrain to the mountains South South East, providing the viewer much flexibility in their precise location along the Cook Inlet region, yet still experience nearly unobstructed views of Mt. Denali, all of which with similar compass bearing. Thus the total angular deviation for the direct sighting of Mt. Denali being a relative small +/- 15^o degrees over the entire viewing region. Therefore, the mountain appearing to sit on the distance horizon with a fairly fixed viewing direction for all viewers in the region. The available area for unobstructed viewing of Mt. Denali covering and estimated 450+ square miles (1,940 sq km) (Fig. 2).

The viewable summer solstice back lighting event, because of Earth's precession of its tilted (obliquity) rotational axis, being of greater time duration today, the Sun being closer to the horizon as it passes beneath Mt. Denali. This event, and at times very dramatic in appearance, being not a single day event, but one viewable near solar midnight for the better part of 6 weeks, weather permitting and highly dominating factor. The duration of time for the event, perhaps shortened to less than a 4 weeks 6,000 years ago (Vid. 1).^[5] The event, being the magnificent backlighting of Mt. Denali (Mt. McKinely massif) for an approximately 1 hour prior to and 1 hour post local celestial midnight (anti Earth point) or (anti meridian). The peak of Mr. Denali today, in terms of azimuthal bearing alignment with respects to the celestial north pole (anti-meridian), being about 50 minutes early. The peak being off by about 30 minutes 6,000 years ago, as seen from Anchorage.^[6]

The fact that Mt. Denali may have been off by such time, perhaps not of great relevance compared to the overall greater experience of viewing the near midnight backlighting of the mountain. The people of the era, perhaps having an affinity for the summer time even, being that the sun is very low on the horizon during the winter appearing to be moving more slowly relative to the ecliptic, hence more difficult to visually determine the time of seasonal (orbital) change. Furthermore, the region near Cook Inlet is typically covered in cloud cover during the fall to spring period of the year, the Sun having fewer average days of visibility, local being difficult to determine, hence the unusual nature of observing the summer solstice at midnight perhaps of greater social importance than the winter solstice. Therefore, given the number of variables, the summer solstice event, still a chance observation because of weather patterns in the region, perhaps offering greatly improved opportunities to mark the end and start of Earth's orbital induced seasonal cycles.

The region around Anchorage, and simply speculating, perhaps signaling to onward travelers in the area when it was most safe to proceed back to Asia or head deeper into the North America continent, safely regulated via the timing of midnight viewing of Mt. Denali.

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The 3 hour 18' minute video recording of the summer solstice backlighting event of Mt. Denali (Mt. McKinley) (Vid. 1), as seen from Anchorage Alaska (Fig. 10) from the top of McKinley Tower, recorded on the night of 17-18 Jun 2013, starting at 11:50 AKDT and ending at 02:08 AKDT which was 171' minutes prior to local celestial midnight (anti meridian) running till 37' minutes past local celestial midnight at 01:41 AKDT, or 07' minutes past local solar midnight which occurred at 02:01 AKDT.^[32] The actual moment of summer solstice for Anchorage Alaska in the year 2013 being 21:04 AKDT, 20 June while the Sun was still above the horizon.

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Using dead reckoning (visiable landmarks), the calculated field of view (FOV) for the video camera being 60^o degrees wide spanning from approximately 308^o to 008^o degrees in azimuthal bearing (Fig. 12).

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Weather conditions in Anchorage preventing the viewing of a cloudless and transparent horizon for anlysis on the actual night of the summer solstice for the duration of the event, and critical factor needed for timing and confirming the azimuthal location of the Sun at the moment of sunset, this visual information being used to help more precisely estimate the location and path of the Sun's motion below the horizon.

The Sun in elevation at local celestial midnight situated approximately -5^o below the horizon and azimuthally 14^o degrees east of Mt. Denali, at local solar midnight, and not particularly relevant though shared for the sake of completeness approximately -5^o30' below the horizon and 20^o degrees to the east. Because of the unusually protracted nature of this solstice event, the Sun being sufficiently close in time and position to local midnight. Other locations withing the viewable area reducing this error to zero.

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The midnight backlighting of Mt Denali, thus full night visibility of the mountain massif, most deffiniately not an observable event by the fall equinox (Fig. 17), already diminishing from view at midnight by the begining of August. The duration of time, thus rate at which the illumination of this background scene advances from diminished viewing to clearly viewable back to diminished viewing, the cycle starting from around the middle of spring and completing by the middle of summer, being more abbreviated and rapid during the 3^rd - ^4th millennia BCE with the Sun placed further in negative elevation from the northern horizon, further within the anti Earth (anti culmination) region.

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Compounding the problem of traveling near the polar region during the summer months is that the nighttime sky from near the artic circle and close to the summer solstice, is too bright in light level to easily view stars in the sky. The inability to directly view such objects and basic bearing indicators such as the north star, Polaris (alpha Uras Major), a star with a brightness of magnitude +1.5,^[xx] hence easy to view even by those needing minor vision correction and or older in age (pupal dialation limitations),^[xx] adversly impacting the ablity of neolithic people to obtain a sense of direction. The aditional problem of increased number of overcast or cloudy days for the northern region,^[xx] futher limiting the ablity of travelers to ganner a sense of direction by using just the Sun and shadow stick (gnomon) method to extrapolate east and west, motivating these people to seak other means for obtain direction headings. The shadow stick method for obtaining north-south, east-west bearing being more difficult in the northern latitudes with the increased incident angle of the Sun relative to the surface along with shadow path distortion produced from the curvature of the Earth.

The high, amibent illumination level of the southern night sky near Anchorage, being easy to notice from the breif video below (McGraw et. al., 2016) and reciprocation of the northern backlighting of Denali mastiff. The video being assembled from a collection of still images taken ~1 minute apart, spanning 2 hours 16 minutes, as seen from a vantage point near Eagle River, Alaska, close to the base of Mount Baldy.^[xx] The first quarter Moon, being just to the south wast when first visable at the top of the video frame, setting towards the western horizon (right). During this near local midnight event, no stars and associated with winter constellation such as Gemini, Auriga, Orion, Canis Major, each of these constellation being composed of bright +1st magnitude (visual, M_v) stars or brighter ^[xx] nor any bright planets during this viewing, being visible in the background. It being possible if orbit condition permit to see Venus and perhaps Jupiter under such bright sky conditions. The brightest star in the sky, with a visual magniude -1.46 such as Sirius,^[xx] if present would have been visible to the unaided (naked) eye and if in the camera field of view, perhaps within the dynamic range of the recording digital sensor.

An equally intriguing possible viewing location of the summer solstice backlighting even of Mt. Denali, and yet to be determined if such sighting is possible, though from cartographical information appears to be well within reason, being the near perfect north south alignment between Mt. Denali and the town of Kenai Alaska , on the western shores of Kenai Peninsula (Fig. 18).^[48]

The region surrounding Kenai Alaska estimated to having been inhabited by humans for 3,000 years (1000 BCE). The distance separating Mt. Denali from Kenai being ~173 miles (278 km). The true north error with respects to Mt. Denali being off by only ~5^o degrees, the longitude error being 13' minutes 20" seconds or ~15.3 miles (24.6 km) over a baseline of 173 miles.^[49] Traveling inland 15.3 miles east toward the mountains of Kenai National Wildlife Refuge in the vicinity of the town of Sterling, this area perhaps providing a more advantageous view of Mt. Denali during solstice, reducing the true north alignment error to zero.

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Such line of sight distance of 173 miles being well within reason, as the volcanic peak of Mauna Kea 13,803' ft (4,207 m), on the Big Island of Hawai`i at a linear distance of 212 miles (341 km)^[52] is on clear day, visible across the water from the city of Honolulu on the Island of Oahu.