Under a whole-sky constellation: the night skies of Yukon-Charley Rivers

Where the Han Athabascans of the Yukon-Charley Rivers region look at the night sky, they do not see separate constellations. The Northern Athabascan idea described by the National Park Service is a single, large human-like figure that covers the whole sky and makes its rounds through the night, with the component constellations as its body parts. The preserve's long, clear, dark nights show that sky well, and they also bring the aurora.

Aurora borealis, which the Han Athabascans call yäjìbaa, over Slaven's Roadhouse in Yukon-Charley Rivers National Preserve. NPS Photo.

A sky that follows the seasons

Summer's long days marked a busy season of gathering and preserving food for the Han Athabascans along the drainages of interior Alaska. In the early 1900s the same long days let workers toil beneath the midnight sun in search of gold in the Coal Creek Historic Mining District. In winter, long nights and the commonly clear skies of a continental climate give a circumpolar view of the stars.

Summer solstice sunset over the Yukon River around 1 am. NPS Photo.

One figure across the sky

This far north, stars appear to rotate around the North Star but generally do not disappear from view, as they do at lower latitudes. That view of the sky is shared across circumpolar North America, much of it home to Athabascan cultures of the Dene linguistic group. The Han Athabascans, "People of the River," have a homeland that stretches across what is now the US-Canadian border and overlaps the preserve. The Charley River is named after a Han leader, Chief Charley.

In Northern Athabascan cultures, knowledge of the stars helped people navigate the landscape during long winter nights. What western stargazers call the big dipper is generally considered by the Han Athabascans to be the tail of a much larger figure. Interpretations vary among Northern Athabascan groups, but the single whole-sky constellation seems to be a common thread. This knowledge was documented only recently, and it replaces earlier western views that Northern Athabascan cultures had little astronomical knowledge. A whole-sky constellation would have mattered for navigation, keeping time, forecasting weather and a cosmology tied to life in a circumpolar landscape.

The big dipper over the Yukon River. NPS Photo.

The aurora

The northern skies also show curtains of green, white and purple. The aurora borealis, the northern lights, is happening at some level all the time but can be seen only against darkness. Solar winds interacting with the Earth's magnetosphere excite gases in the ionosphere, which release light at heights of 60 to 300 miles above the surface. Green is the most common color, and the aurora can also be white, purple, pink or red depending on solar activity and the gases involved.

Displays occur in the aurora oval, centered around the Earth's magnetic north pole. The oval most often lies above about 65 degrees geomagnetic latitude, which overlaps the preserve. When solar storms intensify, its lower edge can expand to lower latitudes and bring powerful displays farther south. The strongest aurora on record was the Carrington event of 1859, seen in middle to tropical latitudes, which disrupted early telegraph systems in the US and Europe. Scientists suggest a similar event could greatly affect today's communications, satellites and electrical infrastructure.

Polar map of the region showing the area of typical aurora activity. NPS image.

Slaven's Roadhouse

Slaven's Roadhouse stands on the bank of the Yukon River near where Coal Creek joins it, and it belongs to the Coal Creek Historic Mining District cultural landscape. It was built in 1932. Miners came after gold was found at the Fortymile River in 1886, near Circle in 1892 and along the Klondike River near Dawson City in 1896. Frank Slaven filed his first claim on Coal Creek in 1905 and worked the creek before building the roadhouse.

In the 1930s Gold Placers, Inc. brought industrial mining to Coal Creek, with a four-story dredge that could overturn as much gravel in a day as 2,400 miners with pickaxes and shovels. Dredging needed warm seasons, so dark skies would have been seen only in spring and fall. The roadhouse was a stopping point for Yukon River travelers, especially in winter, a landing for the company's equipment and supplies, and the local mail stop.

Slaven's Roadhouse c. 1938. USGS, John B. Mertie Collection.

Aurora activity follows the solar cycle, which peaks about every 11 years, so historical records of the cycle hint at what the Coal Creek district may have seen. A graph of that record shows that today's levels of aurora activity are similar to what may have been visible during the gold rushes and the early mining period, and winter visitors in the dredging years may have enjoyed particularly lively northern lights.

Today the roadhouse is one of seven public use cabins in the preserve, reached by boat, plane or sled. It is also a rest stop on the Yukon Quest, a 1,000-mile international sled dog race between Fairbanks, Alaska, and Whitehorse, Yukon Territory, which keeps alive the traditional winter transport used long before the miners, when a rich knowledge of the stars would have mattered.

Sources

• National Park Service, Yukon-Charley Rivers National Preserve, Night Skies over Yukon-Charley Rivers National Preserve; rewritten in hubnx's own words.