Light is necessary for the survival of life on Earth, as almost all energy used by life is derived from the sun. Plants and algae use light energy in photosynthesis, which provides usable chemical energy for heterotrophic organisms. In addition, without light, the Earth would be completely cold and dark, as even the moon gets its glow from reflecting the sun.Know More
Light is also used by many organisms in the sense of sight. While the most significant source of light is the sun, other sources of light, such as fire and electric lighting, are useful to human civilization. Some organisms are capable of producing their own light, or bioluminescence, through chemical means. Examples include the firefly, the railroad worm and the vampire squid. Remarkably, however, bioluminescence produces little heat.
All light is electromagnetic radiation. Visible light is usually between 400 and 700 nanometers in wavelength. Infrared light is characterized by wavelengths longer than those of visible light, while ultraviolet light is typified by wavelengths that are shorter. Wavelength is determined by frequency, where higher frequencies result in shorter wavelengths and lower frequencies in longer ones. The speed of light is considered a constant of the universe at approximately 186,000 miles per second. Photons are the individual unit of light and have properties similar to both waves and particles.Learn more about Our Sun
If the sun stopped shining, the surface temperature of the Earth would drop by a factor of two approximately every two months, according to Cornell University imprint website Ask an Astronomer. This means that the temperature would be too cold for humans within a few weeks.Full Answer >
The sun actually does not rise or set; it is only perceived as rising or setting because of a person's vantage point on the surface of the Earth. This perception of the sun rising and setting is due to the rotation of the Earth itself.Full Answer >
If it were possible to drive from the Earth to the sun, the amount of time required for the journey is slightly more than 1.55 million hours at a rate of 60 mph. That is approximately 64,597 days or about 177 years.Full Answer >
It takes the Earth approximately 365.25 days to complete one revolution around the sun. The extra quarter of a day that is gained each year is why a leap year is added to the calendar every four years. The day added in a leap year is February 29.Full Answer >