The darkest days are upon the residents of the Northern Hemisphere as daylight dwindles and the night lingers longer. Meanwhile, those in the Southern Hemisphere bask in their warmest and longest days—and those at the Equator continue to observe consistent days and nights.

These changing lengths of days and nights depend on where you are on Earth and the time of year. The tilt of the Earth’s axis and its path around the sun affect the number of daylight hours.

Today’s post highlights two simple and elegant animations that help demonstrate how different latitudes experience the sun’s light over the course of one year. The first comes from Reddit user harplass, while the second comes from data scientist Neil Kaye.

Longer and Shorter Days

The Ancient Greeks envisioned the movement of the sun as a Titan named Helios who rode across the sky in a horse-drawn chariot, illuminating the known world below. A rosy-fingered dawn would herald his imminent arrival, while the arrival of the dusk god Astraeus, ever on Helios’ heels, marked the passage of day into night.

Today, time is not at the whims of Greek mythology but by the measurable and consistent movement of celestial bodies. A day on Earth is 24 hours long, but not every day has 12 hours of daylight and 12 hours of night. The actual time of one Earth rotation is a little shorter–about 23 hours and 56 minutes.

Daytime is shorter in winter than in summer, for each hemisphere. This is because the Earth’s imaginary axis isn’t straight up and down, it is tilted 23.5 degrees. The Earth’s movement around this axis causes the change between day and night.

During summer in the Northern Hemisphere, daylight hours increase the farther north you go. The Arctic gets very little darkness at night. The seasonal changes in daylight hours are small near the Equator and more extreme close to the poles.

Length of a Rotation: Equinoxes and Solstices

There are four events that mark the passing stages of the sun, equinoxes and solstices.

The two solstices happen June 20 or 21 and December 21 or 22. These are the days when the sun’s path in the sky is the farthest north or south from the Equator. A hemisphere’s winter solstice is the shortest day of the year and the summer solstice the year’s longest.

In the Northern Hemisphere the June solstice marks the start of summer: this is when the North Pole is tilted closest to the sun, and the sun’s rays are directly overhead at the Tropic of Cancer.

The December solstice marks the start of winter when the South Pole is tilted closest to the sun, and the sun’s rays are directly overhead the Tropic of Capricorn.

The equinoxes happen around March 21 and September 23. These are the days when the sun is exactly above the Equator, which makes day and night of equal length.

Stand in the Place Where You Are

It is always darkest before the dawn, and every passing of solstice marks a time of change. As the Northern Hemisphere heads into the winter holiday season, it also marks the advent of longer days and the inevitable spring and summer.

The lengths of days and nights are constantly changing, but every one will get their time in the sun, at some point.

For anyone reading this article, the benefits of electricity need not be explained.

Access to electricity is now an afterthought in most parts of the world, so it may come as a surprise to learn that 16% of the world’s population — an estimated 1.2 billion people — are still living without this basic necessity. Lack of access to electricity, or “energy poverty”, is the ultimate economic hindrance as it prevents people from participating in the modern economy.

Where are people still living in the dark, and how are these energy challenges being addressed? Let’s dive in.

Where the Grid Reaches, and Beyond

At this point in time, a majority of countries have 100% electricity access rates, and many more have rates above 95%. This includes most of the world’s high-population countries, such as China, Brazil, and the United States.

India is fast approaching that benchmark for access. The massive country has made great strides in a short amount of time, jumping from a 70% to 93% access rate in a single decade.

Meanwhile, North Korea is an obvious outlier in East Asia. The Hermit Kingdom’s lack of electrification isn’t just conspicuous in the data — it’s even visible from space. The border between the two Koreas is clearly visible where the dark expanse of North Korea runs up against the glow of South Korea’s urban areas.

It’s been estimated that more than half of North Korea’s people are living in energy poverty.

Africa’s Access to Electricity

In 1995, a mere 20% of sub-Saharan Africa’s population had access to power. While today’s figure is above 40%, that still means roughly 600 million people in the region are living without access to electricity.

Not surprisingly, energy poverty disproportionately impacts rural Africans. Nearly all of the countries with the lowest levels of electricity access have rural-majority populations:

Nonexistent and unreliable electricity isn’t just an issue confined to rural Africa. Even Nigeria — Africa’s largest economy — has an electrification rate of just 54%.

Where there is an electrical grid, instability is also causing problems. A recent survey found that a majority of Nigerian tech firms face 30 or more power outages per month, and more than half ranked electricity as a “major” or “severe” constraint to doing business.

This is pattern that is repeated in a number of countries in Africa:

Mini-Grids, Big Impact

It has taken an average of 25 years for countries to move from 20% to 80% access, so history suggests that it may be a number of years before sub-Saharan Africa fully catches up with other parts of the world. That said, Vietnam was able to close that gap in only nine years.

Traditional utility companies continue to make inroads in the region, but it might be a smaller-scale solution that brings electricity to people in harder-to-reach rural villages.

Between 2009 and 2015, solar PV module prices fell by 80%, ushering in a new era of affordability. Solar powered mini-grids don’t just have the potential to bring electricity to new markets, it can also replace the diesel-powered generators commonly used in Africa.

For the 600 million people in sub-Saharan Africa who are still unable to fully participate in the modern world, these innovations can’t come soon enough.