The Earth's rotation means that the sun is visible during certain times and blocked during other times. When the sun is visible, it is daytime; when it is blocked, night has come.
In ancient times, people thought that the Earth remained still. To them, the sun appeared to rise and set on a regular but varying basis. Later, astronomers discovered that the Earth orbits the sun and that the Earth rotates in approximately 24 hours. However, the Earth's axis is tilted, which causes days to become longer during parts of the year and shorter during other parts of the year. These fluctuations are fairly small, but they are enough to cause significant temperature variations. These variations create the different seasons.
Day and night also vary based on how close an area is to the equator. Regions close to the equator have only slight variations during the year, so their longest and shortest days are similar in length. Regions far to the north and south of the equator, on the other hand, experience significant variations, and there may be times of the year when the sun never sets or never rises. These variations can cause extreme weather scenarios in these parts of the world.Learn More
The Environmental Protection Agency outlines the protective measures people can take against ionizing radiation as being time, distance and shielding. Taken together, these three factors determine the severity of exposure to radiation, including gamma ray radiation, and the likelihood of long-term health effects.Full Answer >
Meteoroids are pieces of natural space debris that orbit around a larger solar body, such as the sun. They measure about the size of a quarter and are much smaller than other objects that typically orbit. Meteoroids are made from a mix of rock and metals: mostly nickel and irons.Full Answer >
According to Springfield Technical Community College, the visual receptor cells are located at the proximal end of the retina. These cells are called photoreceptor cells.Full Answer >
The sun and planets follow the ecliptic, an imaginary plane in the celestial sphere tilted approximately 23.5 degrees relative to the celestial equator. Earthbound observers see the sun and planets move along the ecliptic arc, rising up from the east and setting in the west.Full Answer >