Light from the Sun
The Sun is the engine that drives our solar system and produces enormous amounts of energy that radiates outward from its core in various forms – visible light, heat, x-rays and radio waves being among them. Since 4.5 billion years ago it has been burning with increasing intensity, and will likely do so for another five billion.
Photons that reach us from the Sun were first produced tens of thousands of years ago at its core before beginning their epic voyage across space to Earth – usually taking 8 minutes 20 seconds on average to arrive.
Throughout its journey through our atmosphere, the main wavelengths of sunlight that travel are red, orange and yellow; these waves pass almost unimpeded through. Blue wavelengths on the other hand are more easily scattered by air molecules and dust particles into space and appear less intense to us; this phenomenon accounts for why sky appears bluer than before.
As the Sun rises and sets, its rays penetrate our atmosphere more vertically and encounter fewer air molecules and dust particles, meaning less blue spectral component of sunlight is scattered compared to when lower in the sky; contributing to a blue tint of sunrise and sunset skies and making for brighter skies than usual and longer twilight hours than normal.
The Sun’s Atmosphere
Light from the Sun travels through Earth’s atmosphere in its various wavelengths or frequencies, each one deflected or scattered differently by molecules in the air based on their thickness. Shorter wavelengths like blue and violet light tend to be scattered more readily than longer ones like red and yellow light – thus, sky color depends on which wavelengths reach Earth.
Once a photon reaches Earth, its energy is dispersed across many paths until most of its energy reaches ionised gases near lower altitudes, where most of it will end up. Ionised gases contain not only hydrogen and helium atoms but also elements like oxygen, carbon dioxide, and nitrogen that scatter photons outward until reaching your eye – this process causes our skies to appear blue!
The layer above the photosphere, known as the chromosphere (“sheath of color”), appears dark because it is opaque to visible light but emits a pink-reddish hue when observed under H-alpha spectral line light of hydrogen atoms (H-alpha). When observed during total eclipse this layer can be seen as crescent- or diamond shaped rings of deep reddish hued chromosphere whereas outside an eclipse it often goes undetected because its brightness overwhelms it compared with that of photosphere eclipsing photosphere!
Scientists have discovered that the chromosphere is highly dynamic, not simply consisting of one flat layer but consisting of filaments, loops and spicules which constantly change shape due to convection – where hot gases rise from below while cool ones sink below – leading to bright lights being given off as solar flares as these structures undergo their dynamic processes.
As you ascend through the chromosphere and transition region to reach corona temperatures increase significantly due to radiation coming from within Sun’s core heating up gases in these layers of space. Although no definitive evidence has yet been discovered to explain why corona temperatures exceed photosphere temperatures it is believed that multiple factors play a part.
The Sun’s Position in the Sky
The Sun’s position in the sky changes throughout the year. On any given day, it rises somewhere along the eastern horizon and sets somewhere in the west; but its daily path is not symmetrical: depending on its latitude location, its angle can be steeper in one direction than in another resulting in some days it only rising high above the horizon at noon while other days not reaching this milestone at all.
At the summer solstice, Earth’s tilt plays an essential part. At this momentous occasion, the Sun rises further north of east than eastward and sets farther northward; thus making noon higher in the sky than at winter solstice.
And its position shifts even more during the equinoxes. Equinoxes occur every March and September and mark the only times of year when it appears that the Sun rises and sets evenly on both sides of its path – an analemma shape formed by this positioning is known by those familiar with mathematics as its term.
Sunlight enters Earth’s atmosphere and is scattered by gases and particles present, creating different colors at various times across its expanse. Blue light, for instance, scatters less than other colors; thus giving rise to blue skies at dawn or dusk when Sun is low on horizon, and red ones at noon when Sun is directly overhead.
Lower in the sky, Sunlight must travel through more atmosphere before reaching our eyes – this means more of its light is scattered or refracted by particles in our atmosphere, giving it its characteristic blue hue.
Have you ever wondered why the sky is blue? Now you know! There are several factors at work, with sunlight being one of the primary influences. Another major contributor is other planets’ atmospheres with different gases and particles in them creating different shades.
The Earth’s Surface
The Earth’s surface contains an immense variety of natural and man-made landscapes, from mountains and valleys to plains and bodies of water such as oceans and lakes. Furthermore, many different plants and animals species inhabit its surface.
As sunlight reaches Earth’s atmosphere it is scattered by gases and particles present. Light that has a longer wavelength such as blue is more likely to be scattered, creating the appearance of a blue sky. With time as the Sun falls lower into its orbit less red light is scattered away and more red can pass through our eyes directly.
From space, Earth appears relatively uniform. Even its enormous mountain ranges appear small compared to its total area; nonetheless, there are many details visible at any one time.
On Earth, our surface is constantly in motion; gravity, wind, ice and the movement of tectonic plates all play their parts in altering its form. Furthermore, human activities change the terrain by building cities, roads and infrastructure projects.
Seventy percent of Earth’s surface is covered with water. This essential source of life on our planet evaporates from the ground as rain or snow, forms clouds, rains back down as precipitation, flows into rivers and lakes and eventually returns to sea as part of the water cycle – making life possible on this planet and providing essential support for plants and animals to survive and flourish; also it allows the Moon and Mars to host oceans – photos taken from space show skies similar to our own planet’s skies.