Animation: Using Planets to Visualize the Speed of Light
The Speed of Light Visualized Using Planets
We often come across the term “light-year” in the context of space travel. But what does it actually mean?
A light-year is the distance light travels in one year. At a speed of 186,000 miles/sec (300,000km/sec), light travels 5.88 trillion miles (9.46 trillion km) in a year—a distance well beyond immediate comprehension.
Scientists created the term light-year to measure astronomical distances beyond the confines of the Earth. And in the vastness of space, light photons, which can go around the Earth 7.5 times in just one second, seem slow.
The above animation from planetary scientist Dr.James O’Donoghue helps put the speed of light into a broader perspective while highlighting the vast distances between celestial bodies.
Light Speed: Fast, but Slow
The Moon is the nearest celestial body to Earth at 239,000 miles (384,400 km) away. A light photon emitted from Earth would get to the Moon in a mere 1.25 seconds.
But how does this compare to other celestial bodies in our solar system?
|Celestial Body||Distance at Closest Approach||Light Travel Time from Earth|
|Moon||0.38 million km||1.25 sec|
|Mars||54.6 million km||3 min|
|Sun||150 million km||8 min|
|Jupiter||588 million km||33 min|
|Saturn||1.2 billion km||67 min|
|Pluto||4.3 billion km||4 hrs|
If you watched the entire length of the above video, you probably saw how “slow” light is. The same photon of light that reached the Moon in a little over a second took three long minutes to reach Mars, the next planet beyond Earth in our solar system.
It takes light just over eight minutes to get from the Sun to Earth. This means that when we look at the Sun, we see it as it was eight minutes ago, and if it were to disappear suddenly, we wouldn’t realize it for eight whole minutes.
Therefore, how “fast” or “slow” light is depends on your perspective. To us Earth-dwelling humans, it feels instantaneous. But the vastness of the universe makes even light seem slow—and it travels at a speed that our spacecraft aren’t even close to matching.
This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.
Visualized: The 4 Billion Year Path of Human Evolution
From single cells to bipedalism, humans have come a long way. Explore the fascinating journey of human evolution in this infographic.
The 4 Billion Year Path of Human Evolution
The story of human evolution is a fascinating one, stretching back in an unbroken chain over millions of years.
From the tiniest protocells to modern humans, our species has undergone a remarkable journey of adaptation, innovation, and survival.
In this article, we take a look at the key developmental stages in the evolution of life on Earth that led to the emergence of Homo sapiens—us!
From Protocells to People
Evolution is the result of millions of minute mutations over millions of years, but the evolutionary process that created us can bucketed into a few key categories.
1. Protocells and Early Microorganisms
The first life forms on Earth were simple, single-celled microorganisms known as protocells. These precursor cells lacked a nucleus or other membrane-bound organelles, and they had simple genetic proteins called RNA.
Over time, RNA complexified into the more stable DNA. Protocells slowly developed specialized organelles, becoming more complex microbes that would eventually form eukaryotes – the complex, unicellular organisms that would birth a diverse array of life forms, from simple sponges to complex animals.
2. The First Animals
Dickinsonia is the earliest example of an animal we know of. Though it was a simple, flat creature that lacked a mouth or digestive system, it symbolizes the first multicellular organism of substantial complexity.
Over time, the first sophisticated organ systems began to arise. Bilateral symmetry emerged, as well as early versions of the nervous and circulatory systems. Simple eyes, called eyespots, also appeared around the time that spinal cords and vertebrate creatures began to emerge.
3. Fish and Tetrapods
One of the most significant developments in the evolution of life was the transition from marine to terrestrial environments.
Up until 500 million years ago, all life was sequestered in the sea. Fish were the first vertebrates and introduced additional organs like stomachs, spleens, and body components like scales, teeth, blood, and more. Bony fish arose, and over time their development brought about sophisticated changes to the skeletal system, eventually producing “proto-limbs” that would enable organisms to walk on land.
Researchers are still unsure which specific organism might have first crawled on land, but candidates share these pre-limb characteristics. Tiktaalik is one popular candidate because it had specialized bones that suggest it could support its own weight while moving out of shallow waters.
These creatures eventually became the tetrapods (“four-footed”), and they had features like four-legs, a backbone, and lungs which could absorb oxygen from air. All the amphibians, reptiles, birds, and mammals that followed are descendants of the original tetrapods.
4. The First Mammals
Around 200 million years ago, the first mammals emerged. These early mammals were small, shrew-like creatures that lived alongside the dinosaurs. Over time, however, mammals evolved hair, specialized teeth, sweat glands to regulate body temperature, and a more efficient circulatory system.
Mammals also brought about features like nocturnality, mammary glands, external genitalia, and a variety of other features that distinguished them from other living species at the time, like birds or reptiles.
5. The Great Apes and First Homo Species
Around 7 million years ago, the first great apes emerged in Africa. These apes, such as orangutans, gorillas, and chimpanzees, were highly intelligent and social creatures that lived in complex communities. Over time, one lineage of apes would give rise to the first members of the genus Homo, which includes our own species.
The main developmental changes during this time were the full-time bipedalism of apes, increasing brain size, and advanced bone development that enabled dexterity for tool construction and hunting. Inventions like fire and clothing arose early in the Homo genus, and eventually complex language, hair loss, and dramatic facial changes would evolve.
Researchers struggle with resolving the exact progression of the Homo species. Many Homo species existed at the same time, and since many fossil records overlap, resolving which ones came first is an area of intense focus.
The Future of Human Evolution
As humans continue to evolve, we can expect to see significant changes in our physical and cognitive abilities over the next 10,000 years.
With the rise of technology and the increasing interconnectedness of the world, we may see a shift towards a more globalized and homogeneous human population, with less genetic diversity.
This has been described as “The Great Averaging”, where genetic diversity minimizes and we start to become more alike.
Other theories suggest that we might develop features like a taller, lighter build, with smaller brains and a less aggressive personality.
However, as with all evolution, these changes will be shaped by a complex interplay of genetic, environmental, and cultural factors. It is impossible to predict exactly how humans will evolve over the next 10,000 years, but one thing is certain: the future of human evolution will be shaped by the choices we make today.
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