2007-05-04 04:23:08 · 5 answers · asked by tanlaask 3 in Science & Mathematics ➔ Astronomy & Space
This is also known as the sidereal calendar. It is the number of days it takes a star to appear in the exact same position in the sky at the exact same hour.
"A sidereal day is a little bit shorter than a solar day because the earth is moving around the sun and it must turn a little bit farther each day to face the sun."
The right ascension of this point is what the clock is based upon, therefore the sidereal clock is a 24 hour clock (24 hrs for one sidereal year)
Astronomers use the sidereal position to locate celestial objects on the 24 hour circle. (5h36min26sec RA +52deg10min35sec Dec)
Right ascension of an object is based upon that object appearing on the meridian (Line from straight overhead to the point due south). It takes one sidereal year for a star that lies on the meridian tonight at 10:00 PM (local time) to return to that position again at exactly the same time. (Local sidereal time)
Looking at the sky as a dome you would slice that dome into 24 equal slices and each slice would be equal to one sidereal hour.
2007-05-04 06:38:41 · answer #1 · answered by Anthony W 3 · 0⤊ 0⤋
The cosmic calendar is the total history of the Universe condensed to one year. The Universe in One Year was inspired by the late astronomer, Carl Sagan (1934-1996). Sagan was the first person to explain the history of the universe in one year-as a "Cosmic Calendar"-in his television series, Cosmos.
It can be seen on the following website and read about in the book by Sagan, The Dragons of Eden.
2007-05-04 04:47:24 · answer #2 · answered by Kris 5 · 0⤊ 0⤋
Imagine that the history of the universe is compressed into one year—with the big bang occurring in the first seconds of New Year’s Day, and all our known history occurring in the final seconds before midnight on December 31. Using this scale of time, each month would equal a little over a billion years.
2007-05-04 04:39:04 · answer #3 · answered by M Series 3 · 0⤊ 1⤋
There's no such thing...people may use it as a figure of speech as in "if we looked back in the cosmic calendar before the present ... ".
2007-05-04 04:29:00 · answer #4 · answered by Gene 7 · 0⤊ 0⤋
m series hit the nail on the head.....the universe is about 13.7 billion years old!!!!!!!
2007-05-04 04:43:43 · answer #5 · answered by Bones 3 · 0⤊ 0⤋