You can find your celestial address by using a star map and finding your coordinates. Star maps are available for sale online and in stores.
To find celestial tower all you have to do is go straight down route 7 and then boom you are there
Look up into the sky. Stars, planets, comets, asteroids, galaxies, etc., are celestial bodies.
After you beat Mugwort, then Twigadamus will give you the sky book, which allows you to learn Celestial Swap.
northern hemisphere
These are imaginary locations in the sky. The "celestial sphere" is a blanket term for everything beyond the Earth. The celestial equator is the plane of the Earth's equator extended out into space. The "celestial poles" are extensions of the north pole and south pole into space. It's sometimes convenient to describe objects out in space with reference to terrestrial coordinates.
By 'Celestial Sign', I presume you're referring to a Celestial Sigil? There is only one location in which to find them, and that is the End Chest of the final arena of the Hall of Heroes. Besides that, you can purchase them from Sigil Traders in various towns and outposts. Usually in the Battle Isles.
Star fields in their relationship to earth.
at the Pokemon league
You find Elgyem on Celestial Tower floors 3, 4, and 5.
You have to evolve it from Litwick, caught at Celestial Tower.
You can find them in Queen Corillia's room
You measure the angles from east from the first point of Aries (which is the place in the sky where the Sun crosses the celestial equator at the March equinox) and north from the ecliptic (declination).