Sunset is the exact time the upper disk of the sun is at the horizon, whereas dusk is when the center of the sun is 18 degrees below the horizon, according to the National Institute of Standards and Technology. The hazy twilight in between sunset and dusk is caused by the scattering of sunlight in the upper atmosphere that gives the horizon a light blue appearance.Know More
Sunset also refers to the end stages of any period, such as the sunset years of a life. Dusk is also the dark part of twilight or partial darkness of an area. Both words come from Middle English terms.
Dusk and twilight also occur in the morning before sunrise. Twilight also refers to the time of night when the western edge of the sky gets darker until the night sky is the same homogeneous color from one horizon to the other. Another definition for the word twilight is a later or terminal period, such as the twilight of the British Empire's power in the 1800s.
Astronomical twilight occurs when the sun is 12 to 18 degrees below the horizon. Nautical twilight is when the sun is 6 to 12 degrees below the horizon, and civil twilight is from sunset until the sun is six degrees below the edge of the earth.Learn more about Our Sun
According to the U.S. National Aeronautics and Space Administration (NASA), the sun is roughly 26,000 light years from the center of the galaxy. Other sources, including Berkley University of California, estimate the distance to range between 25,000 light years to 30,000 light years.Full Answer >
The center of the sun is called its core. At the sun's core, atoms are packed very densely at 14 times the density of lead. The temperature of the core exceeds 15 million degrees Kelvin.Full Answer >
UVA and UVB rays are different forms of ultraviolet radiation that are given off by the sun. UVA is a longer form of radiation than UVB. Both can cause premature skin aging, eye damage and skin cancers, and both of these rays can also suppress people’s immune systems and affect their ability to fight off disease.Full Answer >
Direct sunlight reaches the Earth's surface when there is no cloud cover between the sun and the Earth, while cloud cover causes indirect sunlight to reach the surface. In gardening, sunlight falling directly on the plant is direct sunlight, while indirect sunlight refers to shaded areas.Full Answer >