The only total solar eclipse of 2021 will cross Antarctica early Saturday. Here are its stages explained.

Update for Dec. 4, 2021: The total solar eclipse of Dec. 4 has ended over Antarctica. You can see a video above and see photos and our full wrap story here.

On Saturday, Dec. 4, a total eclipse of the sun will take place, the first since Dec. 14 of last year, when the moon's dark umbral shadow darkened portions of the South Pacific, Patagonia (south Chile and Argentina) and the South Atlantic. But many ardent eclipse chasers passed on last year's eclipse because of the COVID-19 pandemic, so very few people witnessed it. 

Concerning this upcoming solar eclipse, however, the odds are again excellent that only a small contingent of people will very be in a position to see it. And just where does one have to travel this time to see moon completely blot out the sun?

How does Antarctica strike you?

Related: Total solar eclipse 2021: When, where and how to see it on Dec. 4

The tale of the moon's shadow

The northern edge of the moon's dark umbral shadow arrives at 2 a.m. EST (0700 GMT), touching down on Earth some 380 miles (611 kilometers) southeast of Stanley, the capital of the Falkland Islands.

It will take 5 minutes, 48 seconds for the entire umbral shadow to make its way onto the surface of the Earth. By this time 2:05 a.m. EST (0705 GMT), the leading/northern edge of the umbra — which is racing at 2.1 miles (3.4 km) per second — has already pierced 728 miles (1,170 km) east and has crossed over the boundary at 60 degrees south latitude (as recognized by the National Geographic Society) of the Southern Ocean. Thus, initially the shape of umbra's footprint resembles a slender raindrop, about 84 miles (135 km) at its widest but nearly 1,200 miles (1,900 km) long. 

About 250 miles (400 km) east of the northern limit of totality are South Georgia and the South Sandwich Islands, a British Overseas Territory in the southern Atlantic Ocean; a remote and inhospitable collection of islands. No permanent native population lives in the South Sandwich Islands, and a very small non-permanent population resides on South Georgia. King Edward Point is a permanent British Antarctic Survey (BAS) research station on South Georgia Island and is the capital of South Georgia and the South Sandwich Islands. The settlement is the smallest capital in the world by population; currently 12 BAS personnel overwinter at the station, rising to around 22 in summer. If any of them are outside just after sunrise, they no doubt will notice an eerie "counterfeit twilight" that will descend upon the island for a couple of minutes thanks to 96% of the sun's disk being obscured by the moon. 

Around 2:08 a.m. EST (0708 GMT), the umbra will make its first landfall at the South Orkney Islands, a group of islands in the Southern Ocean, about 375 miles (604 km) northeast of the tip of the Antarctic Peninsula. Britain and Argentina both maintain bases on the islands. The Argentine base, Orcadas is sited on Laurie Island. 

Shortly thereafter, the umbra will turn south and then south-southwest over the ice-filled waters of the Weddell Sea — deemed by scientists to have the clearest water of any sea — for 23.7 minutes before making its next — and final landfall on Antarctica. About 66 miles (107 km) northeast of the Filchner-Ronne Ice Shelf, the point of greatest eclipse — that spot along the eclipse track when the distance between the moon's shadow axis and Earth's geocenter reaches a minimum — occurs at 2:33 a.m. EST (0733 GMT). Here, the duration of totality is 1 minute, 54.4 seconds, and the sun's altitude is 17.2 degrees. 

Fifteen seconds later, the umbra makes its first contact with Antarctica, Earth's southernmost continent; the fifth largest and nearly twice the size of Australia. Its landmass is almost wholly covered by a vast ice sheet, covering 98% of the land. Its average thickness is about 5,900 feet (1,800 meters). Ice shelves, or ice sheets floating on the sea, cover many parts of the Ross and Weddell seas. These shelves — the Ross Ice and the Filchner-Ronne Ice Shelf — together with other shelves around the continental margins, fringe about 45% of Antarctica. 

Is it any wonder that the nickname for Antarctica is simply: "The Ice."? 

For the next 30.6 minutes, the moon's umbra will travel southwest, then west and then northwest, traversing the Filchner-Ronne Ice Shelf, skirting across the boundary between Ellsworth Land and West Antarctica, then passing closest to the South Pole — 464 miles (746 km) at 2:50 a.m. EST (0750 GMT) — and finally out over Marie Byrd Land, where it will also pass over the Executive Committee Range — a mountain range consisting of five major volcanoes — before moving back out over the open waters of the Southern Ocean. 

By this time, the umbra has again stretched out into something resembling a cigar; its southern edge has already slipped off the Earth's surface at 3 a.m. EST (0800 GMT) to be followed by the northern edge of the umbra 5 minutes, 45 seconds later. 

Meanwhile, the northern belly of Earth's outer shadow (called the penumbra) grazes the southernmost portion of the continent of Africa so that southern sections of Namibia, Botswana, Lesotho and South Africa see varying degrees of a very small partial eclipse "denting" the top of the sun during the early morning. Cape Town gets about 12% coverage, though in most other cases the amount of the sun that is covered is imperceptibly small (Bloemfontein gets less than 0.5% coverage!). Later, just before it slides completely off the Earth's surface, folks in the southeast corner of Australia, most of Tasmania and southernmost New Zealand can see a small "bite" taken out of the upper left portion of the sun just prior to sunset. 

New moon's close proximity

Another interesting fact is that Saturday's moon will also be making its closest approach (called perigee) to Earth in 2021: 221,702 miles (356,794 km). Even more interesting is that the moment when the moon comes closest to the Earth — 5:07 a.m. EST (0807 GMT) — will come just 144 minutes after the occurrence of new moon. 

So, both the sun and moon will be positioned on the same side of the Earth, with the moon practically at its closest possible point to the Earth. Such "proxigean" moons can produce the highest tides of the year and indeed, ocean tides will be experiencing a far larger than normal range during the few days immediately following this new moon. Low tides, for instance, will be much lower and high tides much higher than usual (hence the term "spring tide," to "spring up"). 

Desperately seeking totality

Getting back to the eclipse for a moment, it has been written that those who have witnessed the beauty of a total solar eclipse firsthand describe them as the most awe-inspiring events that nature can offer. People have traveled great distances just to experience those few precious moments of seeing the sun's corona, chromosphere and prominences. 

Nonetheless, you might be under the impression regarding the Dec. 4 total eclipse, that aside from those few scientists stationed at bases in Antarctica, that nobody else will experience it. That might have been true 40 years ago. In fact, a total solar eclipse that touched Antarctica back in November 1985 was probably only witnessed by a few lucky penguins on the flanks of Mount Sabine. 

But believe it or not, there actually are more than just a hardy few that are willing to make the trek down to the South Polar Region to observe this weekend's eclipse. There is at least a half dozen cruise ships that will sail into zone of totality somewhere between the South Orkney Islands and the Weddel Sea in hopes of getting a view of totality.

And I will be on one of those ships. 

I have been asked to serve on the team of naturalist guides and onboard scientists, on Ponant Cruise Lines' newest expedition ship, Le Commandant-Charcot, a hybrid-electric, polar-class vessel. Guests will disembark onto the ice pack to witness the solar eclipse as the moon passes between Earth and the sun. I am hoping to file a story for Space.com readers about our "Voyage into Darkness" and our attempt to rendezvous with the shadow of the moon. So, stay tuned!

Editor's Note: If you snap an amazing solar eclipse photo and would like to share it with Space.com's readers, send your photo(s), comments, and your name and location to spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.