The Ancient Chinese harnessed solar power for heating and cooling 6,000 years ago

Home energy performance can be boosted through home orientation and shading

When designing a home, placing living areas to the north maximizes sun exposure during winter, while eaves and awnings can limit excessive summer heat. Breezeways and entry air locks can also reduce the dependence on heating and cooling costs.

Humans have used geothermal resources for thousands of years

In North America, Indigenous peoples viewed hot springs as sacred places and used them for medicinal purposes, cooking, and surviving cold weather. The ancient Greeks and Romans also viewed them as sacred, partaking in hot mineral baths to relieve ailments and using them for space heating.

The first rooftop solar panels were installed in 1883

In 1883, New York inventor Charles Fritts created the first solar cell by coating selenium with a thin layer of gold. The cell achieved energy conversion rates of 1 to 2% compared to the 15 to 20% of modern photovoltaics.

The ancient engineers inspiring modern building practices

Modern concrete structures need replacing every 50 to 100 years, so why are buildings by the Maya, ancient Rome, and ancient China still standing strong? This article details how scientists are looking into humanity's past for clues on how to craft long-lasting structures. Part of the problem is adopting old material recipes to hold up to modern demands.

Learn how the Egyptians, Romans, and other ancient civilizations worshipped the sun

In Egypt, the pharaoh was seen as the living embodiment of the son of Ra, the sun god. In Mesopotamia, the sun god Shamash was a divine judge whose light could reveal the truth. Huitzilopochtli, the Aztec god of sun and war, was thought to require sacrifices to prevent the universe's destruction.

East Asian records of auroras may date back to 10,000 BCE

Ancient texts from Japan, Babylon, and China contain accounts of auroras dating back millennia. Because auroral activity and intensity are driven by periodic ebbs and flows in solar activity, these records allow scientists to identify patterns that may help anticipate particularly dangerous future solar storms.

Ancient Chinese marriages began with an elaborate marriage proposal and acceptance between families

The chief objectives of early Chinese marriages involved joining and enhancing the two families and ensuring succession with numerous descendants. Chinese couples still compare astrological signs, although some of the more elaborate rituals of betrothal gifts and sleeping in the “cock loft” are far less common.

China has used several different calendars because of changes in government structure

For many centuries, during which China was an imperial nation, the lunar/lunisolar calendar (aka the “rural calendar”) was the basis for organizing the year. Several attempts were made over the decades to switch to the Gregorian calendar—which begins Jan. 1—but it wasn’t until the People’s Republic of China was founded in 1949 that it stuck.

Many early Chinese restaurants were aimed at travelers

As trade expanded throughout China's north and south in the 12th century, restaurants opened to offer traveling tradesmen their home region's cuisine while they were on the road: southern cooking for people visiting the north, and northern cooking for people visiting the south.

A history of China's ancient hidden tombs

Like many ancient cultures, the Chinese had a tradition of burying the dead in elaborate tombs, which would serve as both burial places and residences for the deceased. Archaeological evidence of these tombs, including those of former emperors, provides insights into the country's cultural evolution.

Medieval European winters were colder than ours, but peasants stayed warm

Medieval winters were colder than ours today while the continent was mired in the so-called Little Ice Age. Without modern technologies, peasants survived with simple, sometimes genius, solutions, including central, chimney-less fireplaces (vented by small, draftless vents) and decorative handwarmers.

Explore a gallery of Bill Nye's energy-efficient home

The Southern California home is painted pale yellow and features double-pane, low-emissivity glass windows to help keep temperatures low. Solar panels are used for electricity and hot water, while Solatube domes and ducts illuminate rooms from above throughout the day, even when the sun is low in the sky.

View historical records of solar observations and discoveries, from telescopes in the early 1600s revealing sunspots to NASA's Parker Solar Probe photographing the sun from within its outer corona in 2025.

How lunisolar calendars work

Despite being called Lunar New Year, the Chinese calendar that the holiday is based on is actually lunisolar, or based on both the sun and the moon. Many religious holidays—including Easter, Ramadan, Chinese New Year, and Passover—do not have fixed dates according to the now-ubiquitous Gregorian calendar.

Enough sunlight hits Earth in just 90 minutes to power the planet for an entire year

Despite this, in 2023, only 5.1% of electricity in the US came from solar energy. Solar panel technology has nonetheless made significant advancements since the 19th century, largely due to NASA's efforts in the space race.

City structures cause localized heat zones hotter than nearby rural areas

Urban materials like asphalt and concrete trap heat, while cities lack cooling features like trees and water. Due to hot runoff, urban streams can heat up by as much as 18°F more than forested streams.

The first practical silicon solar cell was developed at Bell Labs

In 1953, scientists at Bell Labs attempted to develop a power source for phone systems in remote locations, as the dry battery cells lacked the necessary longevity. They experimented with solar power, but the selenium solar cells of the time were too inefficient, eventually leading to the usage of silicon.

Urban planning in ancient Rome

Ancient Rome represents one of the earliest examples of coordinated urban planning from a central government for which researchers have access to contemporary records. This review from MIT showcases ancient Roman cities built on various types of grids, from rectangular outlines to those shaped around two intersecting axes, with several examples and maps provided for each.

Larger shares of solar power generation produce larger energy demand curves

Because solar energy is only available during daylight hours, transitioning an electric grid to solar requires significant ramp-ups and ramp-downs of other energy sources during mornings and evenings to compensate. Widespread adoption of affordable energy storage solutions can soften these curves.

Early timekeeping tools included sundials, water clocks, and astrolabes

Astrolabes also provided a person's latitude based on the height of the stars in the sky, thus aiding in navigation. Incense and candle clocks relied on the constant burning rate of fire to track the passage of time based on premarked locations with equal-interval spacing.

Sand 'batteries' can store excess electricity from the power grid as thermal energy

Energy collected from solar or wind power is used to heat insulated silos full of sand to temperatures as high as 450 degrees Celsius (842 degrees Fahrenheit), which can be retained for long periods. These thermal energy storage systems can be designed to boil water and generate electricity when needed.

The architectural evolution of New York City's Chinatown

Cityscapes continuously evolve, and each stage in their transformation tells a unique story. In Manhattan's Chinatown from the 1940s to today, the architecture has bloomed from an ethnic conclave for often mistreated migrants to a vibrant cultural hub today. See varying elevations and facades over time.

View a photo essay of renewable power landscapes in China

Using a drone, Chinese photographer Weimin Chu captured the deployment of solar and wind power installations across the country, which accounted for half of all global installations in 2025. The images show modern infrastructure juxtaposed with natural landscapes and was featured in an award-winning exhibition presented by Greenpeace in 2025.

The Aztecs synced their solar calendar with a complex 260-day ritual cycle

Researchers have uncovered how the Aztecs aligned their agricultural solar calendar with a symbolic 260-day ritual calendar, utilizing celestial tracking and monuments. Evidence from ruins and writings explains why their new year corresponded to February 23 on the Gregorian calendar.

The earliest earthquake-detection device—the seismoscope—was invented in China in 132 CE and featured eight ball-wielding dragons facing different directions.

The winter solstice has been celebrated globally for millennia

From gatherings at Stonehenge in the UK to celebrations of the triumph of Mithra in Iran, cultures around the world have marked the shortest day of the year in a variety of ways for a very long time. Here are eight known to us today that endure.

Why did this prehistoric culture regularly burn their homes?

This article explores why the Cucuteni-Trypillia culture may have regularly burned their homes. The Cucuteni-Trypillia culture is the oldest known in Europe, dating back to about 5,500 BCE in present-day Romania, Russia, and Ukraine. The...

Is the sun aligned with Stonehenge right now?

Twice a year, during the longest day and night, the sun’s path aligns ever so gently with the ruins of Stonehenge. During the summer solstice, viewers can see the sun’s rise crest the central heel stone. The winter solstice sees the sun set across the site’s altar stone. Use this interactive to tour the historic site and check its current skyscape.

Solar energy alone can fully power the world if transmission hurdles can be resolved

When light strikes a photovoltaic cell, electrons are loosened, which travel through a circuit where the energy can be used. Distributing energy from high solar intensity regions and storing energy for non-daylight hours is logistically challenging and costly.

A clean house is essential for celebrating the Lunar New Year

The earliest recorded instance of this cleaning ritual is from 241 B.C.E. By sweeping out dust and dirt and getting rid of clutter and unwanted items, it’s believed that you won’t carry extra burdens into the new year and will have space for the prosperity and fortune coming your way.

While solar eclipses were considered ominous throughout history, multiple cultures explained the celestial event as the result of mythical creatures nearly consuming the sun.

Researchers once thought Stonehenge functioned as a precise astronomical computer

In the 1960s, scientists used early computers to analyze the stone layout at Stonehenge, arguing it could predict eclipses and other celestial events. This BBC Sky at Night Magazine piece explains how the theory arose—and why scholars now doubt it.

Many of Wright's buildings used radiant heating

Frank Lloyd Wright’s buildings weren’t just radical because of how they looked, but many of them also incorporated stunning technological innovations. Radiant heating is one of Wright’s most popular heating systems, offering the comfort of walking on warm floors on a cold day.

A 1,000 square kilometer patch of solar panels in Africa can power most of Europe

The $500 billion Desertec initiative would have constructed massive solar farms in the Sahara and expansive electrical transmission networks across continents. However, the plan was built on concentrated solar power technology, which is more expensive and less practical than photovoltaics.

Explore global solar resources with this interactive map

One of the biggest challenges to deploying solar panels is whether electricity can be generated reliably when needed, day after day. This detailed interactive map calculates the solar power output potential of regions worldwide and provides a visual comparison between locations such as North Africa and the US Midwest.

The dragon has been central to Chinese culture since ancient times

One of the most recognizable symbols in Chinese culture, the dragon is known as a mighty yet often benevolent creature. The dragon is capable of interacting with gods in the heavens; it can turn invisible, shape-shift, and control the weather. These features made the mythological creature hugely significant to the Chinese people because if they could summon dragons, other aspects of their life could improve.

The solstice has been celebrated globally for millennia.

Take a virtual tour inside Stonehenge, the stone monument built roughly 5,000 years ago.

Prehistoric visitors approached Stonehenge along a processional route known as the Avenue, where the sunrise of the summer solstice aligns with the sarsen stones. This interactive 3D tour recreates that experience with explainer videos and detailed sidebars.

Electric grids that rely on solar power must compensate for reduced electricity generation during solar eclipses.

View US maps of average daily solar resources and solar-based electricity generation

The state you live in can drastically change how much solar energy you can expect to capture to power your home. These National Laboratory of the Rockies maps show where you can reliably generate solar resources.

The history of China: a timeline

How long has China existed, and how and when did it evolve into its form? Explore the journey of China from empire to republic (to a republic, again) in this timeline. Archaeological evidence suggests the earliest Chinese dynasty formed at about...

The greenhouse effect was discovered by analyzing Earth's temperature

Using mathematical techniques developed to analyze heat transfer, Jean-Baptiste Joseph Fourier showed that Earth should be significantly cooler if solar radiation were the only contributor to its surface temperature. By considering that the atmosphere could amplify the sun's warming effect, he formulated what became known as the greenhouse effect.

According to the Greek historian Herodotus, the first person to successfully predict a solar eclipse was the Greek philosopher Thales of Miletus in 585 BCE, with the resulting celestial event ending a half-decade-long war.

Solar panels can create pollinator-friendly habitats by protecting flowering plants

An example of agrivoltaics, where land is used for solar energy production and agriculture, the panels provide clean energy while also shading plants from excessive sunlight. Pollinator-friendly plants can improve water quality and reduce soil erosion by obstructing the wind.

Wind turbines explained

Wind turbines have powered homes since 1887, and today they’re stronger, quieter, and more reliable than ever. Offshore wind could power millions and grow fast enough to meet climate goals.

Solar power is converting the sun's energy into thermal or electrical energy

Solar energy is the most abundant renewable energy resource. It can be captured in photovoltaic cells to generate electricity, solar heating and cooling technologies for temperature control, and concentrated solar power to drive steam turbines.

13 unconventional ways to stay cool during heat waves

While air conditioning is the default solution for many in a heat wave, it can get expensive while requiring the consumption of fossil fuel energy. So, how else can you stay cool during a heat wave? This list compiles some practical, at times quirky, suggestions, including an ice-pack-filled aubergine hat.

Wealthy Egyptians slept on woven beds to allow air circulation in hot climates

The history of beds is a fascinating look at economics, social science, and cultural beliefs around what takes place during sleep. This brief survey of the history of bed-making begins roughly 5,000 years ago and runs through ancient Egypt and Rome to modern Europe. Take a look here.

Aquifer thermal energy storage systems bank water heated during the summer in aquifers—layers of porous rock, gravel, and sand filled with groundwater—which are then collected in winter to warm homes.

How the ancients calculated Earth's size correctly

Watch this seven-minute video to hear Carl Sagan explain how ancient Greek polymath Eratosthenes correctly calculated the size of the Earth in the third century BCE. At some point, Eratosthenes noticed a discrepancy in the length of shadows cast in different cities during the summer solstice. This observation grew into a simple experiment that enabled Eratosthenes, the head librarian at the Library of Alexandria, to calculate the Earth's size precisely.