Astronomy Facts!
1. When you watch the night sky, you notice that all of the objects in the night sky appear to be moving across the sky very slowly from east to west. The apparent speed and motion of everything is due to the rotational speed of the earth. The earth rotates on its axis at about 1,000 miles/hr.
This causes some objects to rise during the night, while others set during the night. We see this in the daytime also, but except for the moon all other objects except for the moon are "drowned" in the bright light from the sun.
Did you know that if you could temporarily turn off the sun in the daytime you would see the sky full of stars. In fact you would be seeing the sky as it was at night six months earlier.
2. The earth moves around the sun in a period of time equal to 365.25 earth rotations. On the average we say that the year (the period of the earth orbiting the sun) is on the average 365 days, acknowledging the need for a leap year every 4th year to take up the slack off throwing away 0.25 days every year. Once every 400th year we throw in a leap year too, because it isn't exactly 365.25 days per year, but is just a tiny fraction over 365.25 each year. That fraction would be about 1/(365.25 x 400) days.
3. When you look at the night sky you are looking outwards into the heavens away from the center of the solar system (the sun). If you were looking into the solar system, it would be daytime and you would see the sun. If you wait six months and look at the night sky you are looking out away from the center of the system in the exact opposite direction from six months ago. The night sky as it will look six months from now or as it did look six months ago is the sky blotted out by the luminous sun in the daytime. All those stars are there, but you can't see them because of the brilliant light of the sun. Only the moon is close enough and large enough in the sky for the reflected sunlight off of its surface to make it visible in the daytime when it is on the same side of the earth as the sun.
4. The one exception to seeing the sky "behind the brilliance of the sun" is during a total solar eclipse. When the moon blocks the sun completely over an area of the earth "the stars come out" and you can see the daytime the rest of the sky, the sky you saw at night six months earlier.
5. A lunar eclipse is the opposite of a solar eclipse. Instead of the moon moving between the earth and the sun (a solar eclipse) casting its shadow on earth, the earth comes between the sun and the moon casting its shadow over the moon.
6. There are so many stars in the heavens no one has an accurate count. It would be reasonable to say trillions and trillions and still be modest in your description. Many of the brightest stars visible to the unaided eye have been named in "ancient" times. The customs and traditions for naming stars have changed over time. Many stars have Arabic names assigned in medieval times when, among Islamic nations, astronomy was a strongly developed science. Star diagrams show Arabic names for the seven stars in the Big Dipper. Later, when Latin was used by European astronomers stars like Polaris (the North Star) were named.
6. Naming an memorizing star names can be a real challenge.
7. Johann Bayer (1603) used the letters of the Greek alphabet.
8. In constructing a star name, a Greek letter is used with the Latin possessive form of the name of the constellation in which the star is located.
The Greek letters are:
a b g d e z h q i k l m
u x o p r s t u f c y w
Their names respectively are:
alpha, beta, gamma, delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu
nu, xi, omicron, pi, rho, sigma, tau, upsilon, phi, chi, psi, omega
This causes some objects to rise during the night, while others set during the night. We see this in the daytime also, but except for the moon all other objects except for the moon are "drowned" in the bright light from the sun.
Did you know that if you could temporarily turn off the sun in the daytime you would see the sky full of stars. In fact you would be seeing the sky as it was at night six months earlier.
2. The earth moves around the sun in a period of time equal to 365.25 earth rotations. On the average we say that the year (the period of the earth orbiting the sun) is on the average 365 days, acknowledging the need for a leap year every 4th year to take up the slack off throwing away 0.25 days every year. Once every 400th year we throw in a leap year too, because it isn't exactly 365.25 days per year, but is just a tiny fraction over 365.25 each year. That fraction would be about 1/(365.25 x 400) days.
3. When you look at the night sky you are looking outwards into the heavens away from the center of the solar system (the sun). If you were looking into the solar system, it would be daytime and you would see the sun. If you wait six months and look at the night sky you are looking out away from the center of the system in the exact opposite direction from six months ago. The night sky as it will look six months from now or as it did look six months ago is the sky blotted out by the luminous sun in the daytime. All those stars are there, but you can't see them because of the brilliant light of the sun. Only the moon is close enough and large enough in the sky for the reflected sunlight off of its surface to make it visible in the daytime when it is on the same side of the earth as the sun.
4. The one exception to seeing the sky "behind the brilliance of the sun" is during a total solar eclipse. When the moon blocks the sun completely over an area of the earth "the stars come out" and you can see the daytime the rest of the sky, the sky you saw at night six months earlier.
5. A lunar eclipse is the opposite of a solar eclipse. Instead of the moon moving between the earth and the sun (a solar eclipse) casting its shadow on earth, the earth comes between the sun and the moon casting its shadow over the moon.
6. There are so many stars in the heavens no one has an accurate count. It would be reasonable to say trillions and trillions and still be modest in your description. Many of the brightest stars visible to the unaided eye have been named in "ancient" times. The customs and traditions for naming stars have changed over time. Many stars have Arabic names assigned in medieval times when, among Islamic nations, astronomy was a strongly developed science. Star diagrams show Arabic names for the seven stars in the Big Dipper. Later, when Latin was used by European astronomers stars like Polaris (the North Star) were named.
6. Naming an memorizing star names can be a real challenge.
7. Johann Bayer (1603) used the letters of the Greek alphabet.
8. In constructing a star name, a Greek letter is used with the Latin possessive form of the name of the constellation in which the star is located.
The Greek letters are:
a b g d e z h q i k l m
u x o p r s t u f c y w
Their names respectively are:
alpha, beta, gamma, delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu
nu, xi, omicron, pi, rho, sigma, tau, upsilon, phi, chi, psi, omega
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