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Fascinating Facts About the Universe

The universe is an endless source of wonder and mystery, captivating humanity for centuries. From mind-boggling distances to extraordinary phenomena, the cosmos offers insights that continuously reshape our understanding of existence. Below, we explore some of the most fascinating facts about the universe, unveiling the marvels that lie beyond our earthly realm.

The Universe Is Expanding Faster Than Ever

One of the most astonishing discoveries in modern astronomy is that the universe is expanding at an accelerating rate. This phenomenon is driven by a mysterious force called dark energy, which makes up approximately 68% of the universe. Scientists hypothesize that dark energy acts as a counterforce to gravity, causing galaxies to drift apart at increasing speeds.

There Are More Stars Than Grains of Sand on Earth

The vastness of the universe is almost impossible to comprehend. Astronomers estimate that there are over 200 billion trillion stars in the observable universe. To put this into perspective, this number far exceeds the total grains of sand found on all the beaches and deserts of Earth combined. Each star is a potential home for planets, fueling the possibility of extraterrestrial life.

Black Holes: The Universe’s Ultimate Mysteries

Black holes are regions in space where gravity is so strong that nothing, not even light, can escape. They are formed when massive stars collapse under their own gravity. The event horizon, the boundary around a black hole, marks the point of no return. Recently, scientists captured the first image of a black hole in the galaxy M87, proving these cosmic enigmas are not just theoretical concepts but real entities shaping the universe.

Light Takes Time to Travel

When you gaze at the stars, you are essentially looking back in time. Light travels at 299,792 kilometers per second, but even at this speed, it takes years for light from distant stars and galaxies to reach Earth. For example, the light from Alpha Centauri, the nearest star system to our own, takes approximately 4.37 years to reach us. This delay provides a unique window into the past of the cosmos.

Dark Matter Dominates the Universe

While dark energy drives the universe's expansion, dark matter plays a crucial role in holding galaxies together. Comprising about 27% of the universe, dark matter is invisible and interacts only through gravity. Without it, galaxies would lack the necessary mass to prevent their stars from drifting apart.

The Observable Universe Is 93 Billion Light-Years Across

Although the universe is approximately 13.8 billion years old, its observable size is much larger due to its continuous expansion. The observable universe spans 93 billion light-years, containing billions of galaxies. Beyond this boundary lies the unobservable universe, which remains a tantalizing mystery.

Neutron Stars Are Incredibly Dense

Neutron stars, the remnants of supernova explosions, are among the densest objects in the universe. A single teaspoon of neutron star material weighs about 6 billion tons. Despite their small size—often just 20 kilometers in diameter—neutron stars exhibit intense gravitational and magnetic forces.

There Could Be Infinite Universes

The concept of a multiverse suggests that our universe is just one of countless others. Some theories propose that these universes may have different physical laws, dimensions, and forms of life. While the existence of a multiverse remains unproven, it continues to be a topic of intense scientific and philosophical debate.

Planets Outnumber Stars

Astronomers have discovered over 5,000 exoplanets, or planets outside our solar system, with the help of advanced telescopes like Kepler and James Webb. These findings suggest that planets may outnumber stars in the universe. Many of these planets reside in the habitable zone, where conditions could support liquid water and potentially life.

Galaxies Collide but Stars Rarely Do

Despite the chaotic appearance of galactic collisions, individual stars rarely collide due to the vast distances separating them. A well-known example is the impending collision between our Milky Way and the Andromeda Galaxy, set to occur in about 4.5 billion years. This event will reshape both galaxies, forming a new, larger structure.

The Cosmic Microwave Background Is a Glimpse of the Early Universe

The cosmic microwave background (CMB) is the faint radiation left over from the Big Bang, offering a snapshot of the universe’s infancy. Discovered in 1965, the CMB reveals crucial information about the universe's early conditions, including its temperature, density, and rate of expansion.

Supernovae Create the Elements of Life

The dramatic explosion of a supernova not only marks the death of a star but also creates and disperses heavy elements like carbon, oxygen, and iron into space. These elements are the building blocks of life, making supernovae integral to the cosmic life cycle.

Time Dilation: A Relativity Phenomenon

Einstein's theory of relativity demonstrates that time is not absolute. For instance, astronauts aboard the International Space Station age slightly slower than people on Earth due to the effects of time dilation caused by their high orbital speed. This mind-bending concept illustrates how space and time are interconnected.

Saturn Could Float in Water

Saturn, the second-largest planet in our solar system, is primarily composed of gas. Its low density means that, theoretically, it could float in water if there were a body of water large enough to contain it. This peculiar fact highlights the diversity of planetary compositions in our solar system.

There Are Rogue Planets Drifting Through Space

Not all planets orbit stars. Some, known as rogue planets, drift aimlessly through the universe, untethered to any stellar system. These wandering planets may have formed in isolation or been ejected from their original orbits.

Pulsars Are Cosmic Lighthouses

Pulsars, a type of neutron star, emit beams of electromagnetic radiation as they spin. These beams create a pulsating effect, similar to a lighthouse beacon. Pulsars are incredibly precise in their rotation, making them valuable tools for studying cosmic phenomena and testing theories of physics.

The Sun Will Become a White Dwarf

In about 5 billion years, the Sun will exhaust its nuclear fuel and expand into a red giant before shedding its outer layers. The remaining core will become a white dwarf, a dense, Earth-sized remnant. This transformation is a natural part of a star's life cycle.

The Universe May End in a Big Freeze

The ultimate fate of the universe is a topic of speculation among cosmologists. One leading theory is the Big Freeze, where the universe continues expanding until all energy is evenly distributed, leaving a cold, dark, and lifeless cosmos. Other theories include the Big Crunch and Big Rip, each presenting a different apocalyptic scenario.

We Are Made of Stardust

Perhaps the most poetic fact about the universe is that we are made of stardust. The elements that compose our bodies—carbon, oxygen, nitrogen, and more—were forged in the hearts of ancient stars. When these stars exploded as supernovae, they scattered these elements across space, eventually forming planets, life, and everything we know.

Conclusion

The universe is an inexhaustible source of fascination, offering endless opportunities for discovery. From the mysteries of dark matter to the life cycle of stars, each revelation deepens our appreciation for the cosmos. As we continue to explore the universe, we uncover not only its secrets but also our place within this grand tapestry of existence.

 


2024 has been a groundbreaking year for scientific advancement, with monumental discoveries shaping our understanding of fields such as medicine, physics, environmental science, and space exploration. These achievements are more than mere progress; they are milestones that could define the trajectory of humanity’s future. Below, we explore the most impactful scientific discoveries of 2024, covering key breakthroughs in genetics, quantum computing, sustainable energy, and more.

1. Advances in Quantum Computing: Breaking Boundaries

In 2024, quantum computing reached unprecedented heights with the first-ever 1,000-qubit quantum computer. This breakthrough has brought quantum processing power close to solving complex problems far beyond the reach of classical computers. Quantum supremacy, once an elusive goal, is now on the verge of realization, making it feasible to tackle challenges in fields ranging from cryptography to pharmaceuticals. Scientists predict that this quantum leap will soon pave the way for advanced drug discovery, climate modeling, and artificial intelligence capabilities that were previously unattainable.

2. Revolutionary Cancer Treatment Using Genetic Engineering

One of the year’s most astounding achievements in medical science is the development of genetically engineered immune cells, specifically designed to target and destroy solid tumors. This innovative approach, known as CAR-T cell therapy 2.0, allows scientists to manipulate patients’ immune cells to recognize and attack cancer cells with high precision. Unlike previous therapies, this new method minimizes side effects while significantly improving recovery rates. Early trials in patients with advanced solid tumors have shown remarkable results, suggesting this method could transform cancer treatment in the years to come.

3. The First Comprehensive Climate Simulation at 1-Kilometer Resolution

Climate science has taken a giant leap forward with the first global climate simulation capable of modeling at a 1-kilometer spatial resolution. This high-resolution simulation allows scientists to understand localized weather patterns, predict extreme weather events more accurately, and develop effective climate adaptation strategies. Powered by the latest advances in supercomputing and machine learning, this breakthrough could play a crucial role in addressing climate change by giving policymakers the tools needed to make more informed decisions about sustainability initiatives, urban planning, and natural disaster preparation.

4. AI-Powered Brain-Computer Interfaces (BCIs) Transform Neurology

The integration of artificial intelligence and brain-computer interface technology has made significant strides in 2024. Researchers have successfully created non-invasive BCIs that allow patients to control digital devices purely through brain signals, improving the lives of those with paralysis or neurological disorders. Powered by advanced neural networks, these AI-driven BCIs interpret brain activity with exceptional accuracy, enabling real-time communication and interaction with technology. This advancement could soon make direct brain-to-machine communication accessible for millions, opening doors to transformative possibilities in neurorehabilitation and assistive technologies.

5. Discovery of a New Exoplanet with Earth-Like Conditions

In the field of astronomy, scientists celebrated a milestone with the discovery of Exoplanet Gliese 581 g, an Earth-like planet located within its star’s habitable zone. Positioned 20 light-years away in the constellation Libra, this exoplanet has an atmosphere similar to Earth’s, as well as liquid water and mild temperatures, making it a prime candidate for supporting life. This remarkable discovery reignites the age-old question of whether we are alone in the universe and bolsters efforts to explore potentially habitable worlds beyond our solar system.

6. Breakthrough in Fusion Energy: Achieving Net Positive Energy

2024 marked a transformative year in energy science with a monumental achievement in nuclear fusion: generating a net positive energy output. For the first time, scientists have created a fusion reaction that produces more energy than it consumes, a feat that has been pursued for decades. This breakthrough brings the world closer to realizing fusion as a limitless, clean, and sustainable energy source. Fusion power could ultimately replace fossil fuels, reducing greenhouse gas emissions and providing an inexhaustible energy supply for future generations.

7. Decoding the Genetic Blueprint of Human Intelligence

In a landmark study, geneticists have identified specific genetic markers linked to cognitive function, offering new insights into the biological basis of human intelligence. By analyzing whole-genome sequences from thousands of individuals, scientists have pinpointed genes associated with memory, reasoning, and problem-solving abilities. This discovery opens avenues for understanding how these genes influence brain development, learning capacity, and neurological conditions. Though still in its early stages, this research may eventually enable personalized approaches to education and treatment of cognitive disorders.

8. Bioengineering Solutions for Plastic Waste Decomposition

This year, biotechnology researchers have engineered a groundbreaking enzyme capable of decomposing plastic waste at an accelerated rate. Derived from a bacteria found in landfills, this enzyme breaks down polyethylene terephthalate (PET) plastics into their base components, which can then be reused to create new materials. With plastic pollution posing a major environmental threat, this discovery holds the potential to revolutionize waste management and reduce the long-term environmental impact of plastic disposal.

9. Successful Trial of CRISPR-Based Gene Therapy for Genetic Disorders

CRISPR technology has again proven its transformative potential with successful human trials targeting genetic disorders such as sickle cell anemia and muscular dystrophy. By precisely editing defective genes, researchers have achieved therapeutic benefits for patients who previously had few treatment options. The success of these trials is a beacon of hope for curing a host of other hereditary conditions, and it paves the way for gene editing therapies that could change the landscape of genetic medicine forever.

10. Advanced AI Models Reshape Drug Discovery

AI-driven algorithms are fundamentally reshaping the pharmaceutical industry. In 2024, the development of advanced AI models capable of predicting molecular interactions has accelerated drug discovery to an unparalleled level. These models can screen billions of compounds in weeks, identifying potential drug candidates far faster than traditional methods. This AI-based approach has already yielded promising compounds for diseases like Alzheimer’s and Parkinson’s, bringing us closer to finding cures for these debilitating conditions.

11. Unprecedented Progress in Synthetic Biology

Synthetic biology achieved new heights this year with the successful creation of a synthetic organism capable of self-replication. Using custom-designed DNA sequences, scientists have engineered life forms that can be programmed for specific tasks, such as bioremediation and carbon capture. This achievement heralds a new era in bioengineering, where synthetic organisms could be deployed to address pressing global challenges, from environmental pollution to resource scarcity.

12. Superconductivity at Room Temperature

Physicists have discovered a new material capable of room-temperature superconductivity, a long-sought goal that could revolutionize everything from power transmission to computing. Previously, superconductivity required extremely low temperatures, making it impractical for widespread use. This new material operates under ambient conditions, enabling the efficient transfer of electricity without resistance, potentially leading to energy grids with zero transmission loss and faster, more powerful electronic devices.

13. Breakthrough in Carbon Capture Technology

In an essential step toward combating climate change, 2024 saw a breakthrough in carbon capture technology with the development of a cost-effective and efficient carbon-absorbing material. This material can capture CO₂ from the atmosphere and convert it into useful byproducts such as building materials and synthetic fuels. With industrial and atmospheric carbon emissions posing a severe risk to the environment, this advancement is critical for global efforts to reduce carbon footprints and mitigate the impacts of climate change.

14. Novel Vaccine Technology for Rapid Response to Viral Outbreaks

2024 has introduced a new vaccine platform that drastically reduces the time required to develop vaccines for emerging infectious diseases. By leveraging RNA-based technology and synthetic biology, scientists can now create vaccines in a matter of weeks instead of months. This platform proved successful during recent viral outbreaks, demonstrating its potential to provide swift protection against future pandemics and significantly bolster global health security.

15. Discovering Life Forms in Extreme Environments on Earth

In the search for life in extreme conditions, researchers discovered new microbial species thriving in some of Earth’s harshest environments, such as deep-sea hydrothermal vents and the acidic hot springs of Yellowstone. These extremophiles reveal how life can adapt to environments previously thought uninhabitable, offering clues about the potential for life beyond Earth. This discovery enriches our understanding of life’s resilience and adaptability and inspires the ongoing search for extraterrestrial life in similarly extreme conditions.

16. Advancements in Sustainable Agriculture through Genetic Engineering

Agricultural science has witnessed a breakthrough in crop modification techniques aimed at enhancing yield and resilience in changing climates. By editing genes associated with drought tolerance and pest resistance, researchers have developed crop strains that require less water and are more resistant to disease. This advancement holds promise for sustainable food production, particularly in regions facing climate-induced agricultural challenges, and could play a crucial role in ensuring food security for future generations.

17. Exploration of the Deep Ocean Yields New Discoveries

Oceanography reached a new frontier with deep-sea expeditions revealing previously unknown marine species and ecosystems. Using advanced robotic submarines equipped with high-resolution imaging, scientists have explored depths beyond previous limits, discovering unique organisms and geological formations. These discoveries deepen our understanding of ocean biodiversity, providing insights into the role deep-sea ecosystems play in regulating Earth’s climate and supporting marine life.

18. Development of Biodegradable Electronics

A team of engineers has developed biodegradable electronic devices, marking a significant step forward in sustainable technology. Made from eco-friendly materials, these electronics decompose naturally without harming the environment, offering a solution to the growing issue of electronic waste. Biodegradable electronics could transform the tech industry by providing devices that meet consumer demands for sustainability without sacrificing functionality.

19. The Rise of Bioinformatics for Personalized Medicine

Bioinformatics, the integration of biology and data science, has revolutionized personalized medicine in 2024. Through advanced data analysis of genomic information, bioinformatics enables healthcare providers to tailor treatments to individual genetic profiles. This approach improves treatment efficacy and reduces the risk of adverse effects, marking a paradigm shift in medical care that could soon become the standard for managing chronic diseases and complex health conditions.

20. Artificial Photosynthesis for Carbon Reduction

In an effort to mimic natural processes, scientists have developed an artificial photosynthesis system that captures sunlight and converts CO₂ into useful organic compounds. This system offers a sustainable method for carbon reduction, potentially offsetting carbon emissions in high-pollution industries. By harnessing sunlight to fuel the process, artificial photosynthesis holds the potential to mitigate climate change and create renewable energy sources.

2024 has indeed been a landmark year in science, with discoveries that promise to shape the future. These breakthroughs not only deepen our understanding of the universe but also offer practical solutions to some of the world’s most pressing challenges. As research and development continue to advance at an unprecedented pace, we anticipate even more transformative innovations on the horizon.


The key to conquering addictions and psychiatric problems is hidden deep within our brains' netherworld and the circuitry that makes us feel good.



This part of the brain, like space, requires greater investigation.

The mesolimbic dopamine system, which consists of neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens—a critical structure in mediating emotional and motivation processing—is the oldest and most well-known reward pathway.

Dopamine is a neurotransmitter produced when the brain anticipates a reward. Eating pizza, dancing, shopping, or sex can all cause a surge in dopamine. However, it can also be caused by drugs, which can lead to substance abuse.

Researchers are exploring for pathways other than dopamine that could play a role in rewards and reinforcement in order to find new strategies to treat addiction and psychiatric disorder.

Researchers from the Bruchas Lab at the University of Washington School of Medicine pushed the study on our reward pathways further in a report published in Nature Neuroscience, discovering that there is additional channel beyond dopamine. The Bruchas Lab is advancing our understanding of the brain's inner workings and developing treatments for psychiatric disorders.

"This study opens up new avenues for understanding reward circuitry that may be altered in nicotine, opiates, or other drug abuse, as well as neuropsychiatric diseases that affect reward processing, such as depression," said corresponding author Dr. Michael Bruchas, who runs the Bruchas Lab at the University of Washington School of Medicine.

Researchers discovered that GABA neurons make up about 30% of cells in the VTA in this study. VTA GABA neurons are becoming more well recognised as participants in reward and aversion, as well as prospective therapeutic targets for addiction, depression, and other stress-related diseases.

Neurons are the basic building blocks of the brain and nervous system; they are the cells that receive sensory input from the outside world, give motor commands to our muscles, and transform and relay electrical signals at every step along the way.

"We discovered unique GABAergic cells that project broadly to the nucleus accumbens, but only projections to a specific portion contribute to reward reinforcement," said Raajaram Gowrishankar, a postdoctoral scholar in the Bruchas Lab and the Center for the Neurobiology of Addiction, Pain, and Emotion.

Researchers discovered that long-range GABA neurons from the VTA to the ventral, but not the dorsal, nucleus accumben shell, are involved in reward and reinforcement behaviour in both male and female mice. They discovered that this GABAergic projection suppresses cholinergic interneurons, which are important actors in reward learning.

The researchers claimed that their findings "improve our understanding of neural circuits that are directly implicated in neuropsychiatric disorders including depression and addiction."

The findings, according to co-lead author Ream Al-Hasani of Washington University's Center for Clinical Pharmacology, are similar to putting together Legos and figuring out how one component links to another.

Each puzzle piece can take years to complete.

The discoveries, according to Gowrishankar, are allowing scientists to better comprehend brain subregions and visualise how certain neuromodulators are released during reward processing.

The researchers are able to emphasise heterogeneity in the brain, or differences in the brain, in scientific terms.

"It's critical that we don't think of brain structures as monolithic," Gowrishankar added. "In the brain, there is a lot of subtlety. It's amazing how plastic it is. The way it's set up. This discovery demonstrates one way in which disparities can manifest."

 




When the rotating air of an updraft (shown in purple) collides with the revolving air of a downdraft (shown in aqua) that has turned upward, a tornado can emerge.

Tornadoes can only arise when a thunderstorm has a specific wind pattern.

When the air rising in thunderstorms is impacted by winds flowing in opposite directions, it might begin to spin. It rises and is pushed to one side by the wind. It rises a little higher before being jolted again by wind blowing in the opposite direction. The ascending air begins to spin due to winds travelling at various speeds and directions at various heights.

Supercells, the most powerful type of thunderstorm, have air that spins as it climbs, although not all spinning air produces tornadoes.

There must also be spinning air near the ground for a tornado to occur. This occurs when the storm's air sinks to the ground and spreads out in gusts across the countryside. Warmer air rises when the wind blows. As they blow across the land, gusts of cooler air settle.

The air near the ground begins to spin if there are enough rising and descending gusts.

As it is pulled inward nearer its axis of rotation, the spinning air near the earth accelerates up. This is similar to how figure skaters spin quicker when their arms are brought in rather than outstretched. This is known as angular momentum conservation.

The rising, rotating air can tilt the rotating air vertically, causing it to move horizontally across the land. As a result, a tornado can form.

Supercell thunderstorms produce the majority of tornadoes, however not all supercell thunderstorms produce tornadoes. For a tornado to occur, the whirling air near the ground must rotate fast enough. If the rotating air near the ground is extremely cold, it will spread away from the storm and slow down like a figure skater with extended arms, preventing a tornado from forming.



Our world is made of elements and combinations of elements called compounds. An element is a pure substance made of atoms that are all of the same type. At present, 116 elements are known, and only about 90 of these occur naturally.

Rights: Pslawinski, Creative Commons 2.5

Neon sign

Neon – element number 10 on the periodic table – is an inert gas discovered by Sir William Ramsay in 1898. It is used in making neon advertising signs.

Elements and the ‘Big Bang’ theory

During the formation of the universe some 14 billion years ago in the so-called ‘Big Bang’, only the lightest elements were formed – hydrogen and helium along with trace amounts of lithium and beryllium. As the cloud of cosmic dust and gases from the Big Bang cooled, stars formed, and these then grouped together to form galaxies.

The other 86 elements found in nature were created in nuclear reactions in these stars and in huge stellar explosions known as supernovae.


Universal element formation

Elements are formed deep within the cores of certain types of star. Find out more in this interactive.

Elements and our Sun

For most of their lives, stars fuse elemental hydrogen into helium in their cores. Two atoms of hydrogen are combined in a series of steps to create helium-4. These reactions account for 85% of the Sun’s energy. The remaining 15% comes from reactions that produce the elements beryllium and lithium.

Rights: Public domain - worldwide

The Sun

At this stage of our Sun’s life cycle, hydrogen atoms are fused to form helium atoms. This nuclear reaction produces very large amounts of energy.

The energy from these nuclear reactions is emitted in various forms of radiation such as ultraviolet light, X-rays, visible light, infrared rays, microwaves and radio waves. In addition, energised particles such as neutrinos and protons are released, and it is these that make up the solar wind.

Earth is in the path of this energy stream, which warms the planet, drives weather and provides energy for life. The Earth’s atmosphere is able to screen out most of the harmful radiation, and the Earth’s magnetic field can deflect the harmful effects of the solar wind.

Dying stars

When a star’s core runs out of hydrogen, the star begins to die out. The dying star expands into a red giant, and this now begins to manufacture carbon atoms by fusing helium atoms.

More massive stars begin a further series of nuclear burning or reaction stages. The elements formed in these stages range from oxygen through to iron.

During a supernova, the star releases very large amounts of energy as well as neutrons, which allows elements heavier than iron, such as uranium and gold, to be produced. In the supernova explosion, all of these elements are expelled out into space.

What is the Big Bang theory?

Dr David Krofcheck is a particle physicist who believes that the Big Bang is how matter came about.

Our world is literally made up of elements formed deep within the cores of stars now long dead. As Britain’s Astronomer Royal Sir Martin Rees said, “We are literally the ashes of long dead stars.” When you buy a party balloon that floats in air, it is filled with helium gas – most of which was created when the universe was only 3 minutes old!

Examples of element making (nucleogenesis) in helium burning reactions:

  • 3 helium atoms fusing to give a carbon atom: 3 @ 4He → 12C

  • carbon atom + helium atom fusing to give an oxygen atom: 12C + 4He → 16O

  • oxygen atom + helium atom fusing to give a neon atom: 16O + 4He → 20Ne

  • neon atom + helium atom fusing to give a magnesium atom: 20Ne + 4He → 24Mg

Man-made elements

Only 90 of the 116 known elements occur naturally, so where have the other 26 come from?

The answer is to be found in the development of nuclear power plants and machines known as particle accelerators:

  • Scientists discovered that, by allowing fast neutrons to collide with the common isotope of uranium known as U-238 in a nuclear reactor, the ‘new’ element plutonium was made.

  • By smashing atoms together in machines known as particle accelerators, it was discovered that new elements could be made. For example, bombarding atoms of the element curium with atoms of neon made element 106 – seaborgium.





When children draw pictures of the Sun, they often show rays radiating outwards – similar to the image below.

 

The Sun

At this stage of our Sun’s life cycle, hydrogen atoms are fused to form helium atoms. This nuclear reaction produces very large amounts of energy.


These light rays travel in a straight line at nearly 300,000 kilometres per second. Sunlight that travels towards the Earth takes just over 8 minutes to reach us. When the rays reach Earth, they hit whatever is in their path. If the object they hit is opaque, the light cannot pass through, and a shadow forms.

Simply speaking, a shadow is an absence of light. If light cannot get through an object, the surface on the other side of that object (for example, the ground or a wall) will have less light reaching it.

A shadow is not a reflection, even though it is often the same shape as the object.

Light sources and shadows

There are many sources of light – stars like our Sun, candle flames, light bulbs, glow-worms and computer screens produce light. All of this light travels in a straight line until it hits something. Sometimes, it travels a short distance – like when we switch on the lamp. Other times, light travels thousands of years – like the light from stars we see in the Milky Way.

It is easy to see our shadows when we are outdoors in the sunshine on a clear, bright sunny day, but do shadows form when an object blocks light from other sources? The answer is yes, but they may be difficult to see if the light source is not very bright (has a low light intensity). Shadows are also more definite (sharper) where there is contrast between the shadow and the lit surface, for example, a shadow on a white wall will be more easily seen.

The size of the light source can sharpen or blur the shadow. A small spotlight like a cellphone torch forms a more distinct shadow than an overhead room light, but the sharpness of the shadow changes when the torch moves away from the object.

Long penguin shadow

The Sun is low on the horizon so the penguin’s shadow is long. An object is always between a light source and the surface on which its shadow forms.

Changing shapes and sizes

A shape of an object always determines the shape of its shadow. However, the size and shape of the shadow can change. These changes are caused by the position of the light source.

When we are outside on a sunny day, we can see how our shadows change throughout the day. The Sun’s position in the sky affects the length of the shadow. When the Sun is low on the horizon, the shadows are long. When the Sun is high in the sky, the shadows are much shorter. We can create the same effects indoors by changing the position of a torch as it shines on an object.

Although the shadow effects are the same, the reasons for the moving light source are very different. When we use a torch to make long and short shadows indoors, it is the light source that moves. When the Sun makes long and short shadows outdoors, it is the Earth, not the light source (Sun), that moves.

 

The Sun appearing in the east

As the Earth’s axial rotation spins our planet towards the light of the Sun, we see the Sun appear in the east. Due to the Earth’s rotation, our view of the Sun changes throughout the day.

The spinning Earth

From our vantage point on Earth, it appears that the Sun moves across the sky during the day. We see the Sun appear to rise in the east and set in the west. Actually, the Earth is spinning (rotating on its axis) so it is our view of the Sun in the sky that changes during each 24-hour cycle of light and dark.

We see the sunrise when our location on Earth spins towards the light of the Sun. As the Earth continues to spin, we see the Sun higher in the sky. As the Earth spins away from the light, we see the sunset. The Earth continues to spin until we are in a shadow – our place on Earth is dark because the Sun’s light is blocked by the magnitude of our planet! We have several hours of night with our side of the Earth in darkness, and then as the Earth spins towards the Sun’s light, we see a sunrise. When New Zealand is in darkness during the night, the opposite side of the world is in sunlight.

Shadows change with the seasons

The tilt of the Earth’s axis affects the length of our shadows. During the summer, our location is tilted towards the Sun, so our midday shadows are very short. During the winter, our location is tilted away from the Sun, so our midday shadows are longer.


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