Astronomy relevant to astrology
1. GEOCENTRIC AND HELIOCENTRIC SYSTEM
Hindu astrology is known as pratyaksh shastra which means what is visible of the apparent movement of planets. In geocentric observations the Earth is taken as the center of the universe. Through we know that Earth is moving like other planets around the sun, yet for the purpose of ease of understanding Astrology we continue to follow the ancient geocentric system of observations. In heliocentric observations the Sun is at the center of the universe and other planets revolve round it. For convenience Astrologers use geocentric system.
The broad belt of about 16-degree extending 8-degree on either side of the ecliptic, in which all the planets revolve, is known as Zodiac. This 16 degrees wide and 360° elliptical band in the heavens is divided into 12 equal parts or imaginary compartments of 30° each. They are called the signs of zodiac. Each Sign is named after a prominent constellation situated in it. There are 27 Nakshatras or constellations of 13° 20’ each located in each Sign. Astrologically, there are further divisions of Nakshatras.
Sign refers to certain area of the sky along with all stars in it. The 12 Signs each comprising 30 Degrees of space; are as under:
1. Aries (Mesh)
2. Taurus (Vrish)
3. Gemini (Mithun)
4. Cancer (Kark)
5. Leo (Simha)
6. Virgo (Kanya)
7. Libra (Tula)
8. Scorpio (Vrishchik)
9. Sagittarius (Dhanu)
10. Capricorn (Makar)
11. Aquarius (Kumbh)
12. Pisces (Meen)
4. THE EARTH
This planet is third in distance from the Sun and the only planet, which has life (as known to the mankind). It rotates on its axis in about 23 hours and 56 minutes. The Earth takes about 365.25 days to complete on orbit around the Sun and has one natural satellite called the Moon.
The Earth rotates or spins on its axis from west to East. Therefore all heavenly bodies appear to be moving or orbiting the Earth from east to west. The Earth’s axis is tilted at 23 degrees and 26 minutes to a line perpendicular to the Earth’s orbit around the Sun.
The Earth’s spin is slowing down by about 1 second every 90,000 years. This might not sound much, but when the Earth came into being it use to take about 10 hours to spin once on its axis.
The imaginary line, which divides the Earth’s globe into two equal parts and is perpendicular to the axis of the Earth, is known as the Equator. It divides the Earth’s sphere into two equal halves called the Northern and southern hemispheres. All points at the equator are equidistant from the North & south poles.
If we draw imaginary lines of concentric circles on the globe of the Earth [concentric means having the same or common center as the center of the Earth], passing through the north and south poles, then these circles will cut the Equator at right angles. These imaginary lines are known as the meridians of Longitudes. Longitude is measured East or West of the Prime meridian. The Prime meridian on the Earth passes through the original royal Greenwich Observatory near London. Therefore the meridian passing through Greenwich is considered the circle of zero Longitude and all places falling on this meridian have 0 degrees Longitude. It was accepted as the prime meridian of world at the Washington Conference of 1884. All places located East of this meridian have 0 to 180 degrees East Longitudes and places located West of this meridian have 0 to 180 degrees West Longitudes. 180 degrees East and 180 degrees West is the same meridian circle lying opposite to Prime meridian and is called the International Date Line.
If we draw imaginary circles parallel to the Earth’s equator the centers of which fall at the axis of the Earth, these imaginary lines are known as parallel of Latitudes. All places located at the equator have 0 degree Latitude. Place located North of equator will have 0 to 90 Degrees North Latitudes and places located South of equator will have 0 to 90 Degrees South Latitudes depending upon the location of these places. The point of intersection of 0 degree longitude and the Earth’s Equator is the reference point for locating any place on the Earth. In short we can say that the longitude of a place is the angular distance of the place’s meridian, East or West of the Prime meridian. Whereas latitude of a place is its angular distance North or South of the equator, measured along its meridian. With these coordinates namely the longitude and latitudes, any place on the Earth can be located.
8. THE MOON
It is the only natural satellite of the Earth. We consider moon as luminary although it does not have light
Moon’s ‘day’ is exactly the same length as the time taken for the Moon to go once round the Earth therefore Moon keeps the same face turned toward us all the time and there is part of the Moon that we can never see from Earth.