Six months of night at the South Pole

At home, the Sun rises and sets every day.

At the South Pole, it rises only once a year, in September. Then it stays up all summer. In March it sets, and it is night for six months.

At the South Pole, there is just one sunrise and one sunset a year. The Sun sets around 20 March, at the start of autumn in the Southern Hemisphere, and does not come back for about six months. In 2024, NOAA technician Krystian Kopka photographed the sunset on 20 March.

Around 22 September, the Sun rises again. It then stays in the sky all summer. Kopka described the Sun "circling overhead the entire summer." The Sun can sometimes peek over the horizon a day or two early, because Earth's air bends its light, but storms can hide it.

NOAA reports that South Pole staff experience just one sunrise and one sunset per year. In 2024 the March 20 equinox brought the last appearance of the Sun for six months, and NOAA technician Krystian Kopka, who had been at the Pole since November 2023, described the Sun circling overhead the whole summer and setting "in slow motion."

The return comes near the September equinox. NOAA's 2009 release explained that staff would officially see the center of the Sun cross the horizon at the equinox time on 22 September; with clear skies, atmospheric refraction (the bending of light rays as they pass through the atmosphere) can make the Sun visible as much as two days earlier, while storms can greatly alter when, or whether, the first glimpse is seen. Once risen, the Sun stays visible until the March equinox. NOAA adds that the coldest temperatures of the year are often recorded just before the Sun's return.

The Earth is tilted, like a leaning top.

For half the year, the South Pole leans toward the Sun, and it is always light. For the other half, it leans away, and it is always dark.

Earth's axis, the imaginary pole it spins around, is tilted. As Earth travels around the Sun, the tilted axis always points the same way in space. So around December, the South Pole tilts toward the Sun, and around June it tilts away.

That tilt is what causes the seasons, NASA explains. At the very pole, it means that from the September equinox to the March equinox the Sun circles around the sky without setting, and from March to September it stays below the horizon.

NASA explains that seasons are caused by Earth's tilted axis: as Earth orbits the Sun, the axis keeps pointing in the same direction, so different parts of Earth receive the Sun's most direct rays at different times of year, with the South Pole tilted toward the Sun around December. NASA also stresses that Earth's changing distance from the Sun is not the cause; perihelion, the closest approach, falls in January.

At 90° S this geometry produces the extreme case. NOAA reports the Sun above the horizon continuously from about the September equinox to the March equinox and below it for the rest of the year, with refraction and weather shifting the moments of first and last sight by a day or more.

In winter, airplanes cannot fly to the South Pole.

It is too cold and too dark. A small team stays all winter. They can't leave until spring comes back!

Staying at the Pole through winter is called "wintering over." In summer, from about November to mid-February, most people fly in from McMurdo Station on ski-equipped airplanes, fuel and cargo often come over the snow, and up to 150 people live at the station in a week. Then the station closes to flights.

NOAA says that in winter it gets so cold and dark that aircraft systems don't work, so for about nine months, six of them in darkness, no flights go in or out. Up to 42 people stay for the winter. The station's 2016-2018 guide said a doctor could be reached on the station at all times.

Most people reach the Pole from McMurdo on ski-equipped aircraft, while cargo and fuel often come by surface traverse; summer resupply, November to mid-February, brings up to 450,000 gallons of fuel (NSF). NSF counts up to 150 people in a summer week, up to 42 in a winter week and 640 passing through each year. The 2016-2018 Participant Guide described the station as isolated for most of the year, from mid-February to late October.

NOAA explains why its own staff serve one-year tours: in winter it is so cold and dark that aircraft systems do not work, so for nine months, six of them dark, no flights go in or out. Its 2009 release adds that LC-130 aircraft can begin summer resupply flights from McMurdo once the surface temperature warms to about -50 °C. The guide also noted that a physician is accessible on station at all times. The first group ever to winter over at the Pole was the 18-man U.S. Navy crew that built the original station.

Everyone at the station helps out.

They take turns cleaning and washing dishes. They eat together, play in the gym and grow plants in a little greenhouse. They save water, so showers are short!

Life at the station is a team effort. The station's 2016-2018 guide described it: everyone took turns with housekeeping chores, including cleaning bathrooms, and volunteers helped wash dishes. Three free meals were served each day, cafeteria style. The rule was to eat everything you take, because every bit of thrown-away food had to be flown out.

Water was precious: people were allowed two showers of two minutes each week, and one load of laundry. For free time, there was a big gym, a sauna, a music room, movie lounges and a small greenhouse with a lounge.

NSF (2024) counts about 47 buildings at the station, including housing, a food growth chamber and dining, and 24,354 meals served a year. The 2016-2018 Participant Guide described an elevated station holding 154 rooms, offices, a cafeteria, a gymnasium, a store and a post office. Meals were free, cafeteria style, three a day, with the reminder that every piece of food thrown away had to be flown out. Housekeeping was shared on a rotating basis by all personnel, and most work centers also had weekly station chores.

That guide called water conservation critical, limiting each person to two two-minute showers and one load of laundry a week. Recreation included a large gym, weight and cardio room, sauna, arts and crafts room, reading room, a small greenhouse with a public lounge, two movie lounges, a pool room and a music room. Connections outside were limited: internet and email worked only during short windows of satellite coverage, and mail traveled on resupply aircraft through McMurdo. These details may since have changed.

The clear, dry sky at the South Pole is great for studying stars!

Scientists use big telescopes at the South Pole. They also study the air, the ice and even tiny particles called neutrinos.

NOAA calls the South Pole station the coldest, most remote research facility on the planet. The average temperature over a year is about minus 49 degrees Celsius, and in winter it can drop below minus 80.

NSF says its clear, dry air and the absence of light pollution make unique astronomy possible. Scientists run the South Pole Telescope and IceCube, a giant detector buried in the ice that catches tiny particles called neutrinos. NOAA and the groups before it have measured the air there since 1957, including carbon dioxide.

The climate is extreme: NSF gives an annual average around -49 °C (-56 °F) with winter temperatures that can fall below -80 °C (-112 °F); the 2016-2018 Participant Guide gave monthly averages from about -28 °C in summer to -60 °C in winter, a record low of -82.8 °C in June 1982 and a record high of -12.3 °C in December 2011.

NSF credits the clear, dry air and the absence of light pollution with allowing unique astronomical observations. The station hosts the Martin A. Pomerantz Observatory, NOAA's Atmospheric Research Observatory, the South Pole Telescope, seismic instruments and the IceCube South Pole Neutrino Observatory, an in-ice neutrino detector. Research spans astronomy and astrophysics, aeronomy, auroral and geospace studies, meteorology, geomagnetism, seismology, earth-tide measurements and glaciology. In 2009 NOAA wrote that its South Pole carbon dioxide record, begun in the International Geophysical Year of 1957, was the longest atmospheric carbon dioxide record on Earth, a year older than the Mauna Loa record; in the twelve months before September 2009, its winter crew released about 70 ozonesondes, ozone-measuring instruments, on high-altitude balloons.