People once believed that the stars were attached to a huge sphere that rotated around the Earth once a day. Today we know that the stars and all the heavenly bodies lie at different distances from us and that they only appear to move around the Earth (from east to west) because the Earth itself is spinning on its own axis (from west to east). When describing the positions of stars and the ways in which they a
THE EQUATORIAL COORDINATE SYSTEM Declination in the sky is measured in the same way that latitude on Earth is measured, in degrees, minutes, and seconds north and south of the equator in this case, the celestial equator. It increases from 0 degrees on the equator to 90 degrees at the poles. North of the celestial equator declination is listed as positive (+), while south is negative (-).
The celestial equivalent of longitude on Earth is called right ascension (abbreviated RA), and is measured not in degrees, as longitude is, but in units of time: hours, minutes, and seconds (where 24 hours equals 360 degrees and one hour of RA equals 15 degrees of arc). The right ascension of Polaris is referred to as 1 hour, 49 minutes, and that of Rigel 5 hours and 12 minutes. The zero (0) line of RA (the celestial equivalent to Earth's Greenwich meridian of longitude) passes through the point where the Sun crosses the celestial equator at the first moment of spring in the northern hemisphere,the vernal equinox. Hours in right ascension are measured
eastward from this point, until we reach 23 hours, 59 minutes. One minute later, we find ourselves back at o hours. I will show how to find the RA of planets later in celestial navigation blogs. Also I have a easy way of finding a star that you don't know by using the star finder and putting it in a format.
If you are trying to explain to a observer where an object is in the sky at any particular moment,This system is mainly used for navigation, but it also enables skywatchers to specify the position of a celestial body with respect to their horizon and at a particular time using coordinates called altitude and azimuth. These figures differ for each observer, depending on his or her position on Earth and the time that the observation is made.
ALTITUDE, (ALSO KNOWN AS ELEVATION) This is the angle above the observer's horizon, The point directly overhead, at 90 degrees, is known as the zenith.
AZIMUTH This is the angle measured clockwise from north along the horizon to the point on the horizon that lies beneath the star, N = 0 degrees or 360 degrees, E = 90 degrees, S = 180 degrees, and W = 270 degrees.
MERIDIAN This is an imaginary ,great circle that passes through your zenith from north to south, dividing the sky in two, the eastern and the western halves.
It is important to be aware of this line because when a object crosses it, it's as high in the sky as it's going to get.
The Sun crosses the line of the meridian around noon every day. We say that the Sun, or any star, culminates when it crosses the meridian.
