Celestial Locator Grid

On thing that I have long been really interested in, and have not yet discussed on this blog system, is the possibility of extending the system of latitude and longitude, that we use to describe locations on the earth's surface, into outer space.

We have great difficulty in describing precise points in space. We make use of the background of constellations and distance from the sun, but it leaves a lot to be desired.

The standard system of degrees north and south of the celestial equator and declination are used to pinpoint astronomical objects. The expression of a remote location in terms of angular degrees has the advantage in that it is the way in which human beings look at things. The disadvantage is that it becomes less and less accurate the further away the remote location is.

Those who have read my book "The Patterns Of New Ideas" will recall that I presented a solution entitled "The Celestial Meridian", a straight line between the centers of the sun and the star Regulus, as the foundation of such a grid locator system in space. I chose Regulus because it is not only a bright star but is on the ecliptic, the line of the apparent movement of the sun across the background stars during the course of the year. The ecliptic is shaped like a sine wave due to the tilt of the earth's axis, which also produces the seasons.

Today, I would like to present another possible plan for a grid locator system in outer space which follows the same concept as the latitude/longitude system used on the earth's surface.

The trouble with trying to institute such a system is the lack of fixed reference points in space. In our Solar System, everything except the sun is in continuous relative motion. The planets are not even at fixed distances from the sun and do not orbit the sun in exactly the same lateral plane.

For example, there is a difference of about five degrees in the planes of the moon and the sun. If they were in the same plane, there would be both a lunar and a solar eclipse every month. Comets tend to orbit the sun far above and below the general plane of the planetary orbits.

Why not extend the earth's compass directions into space? North and south are already well-defined. The points in space directly above the north and south poles always remains the same. The earth's poles actually do shift, but only over the course of thousands of years.

The difficulty here is that the tilt of the earth's axis and the continuous variation in the overhead position of the sun on the earth's surface, from the Tropic of Cancer to the Tropic of Capricorn, producing the apparent sine wave in the ecliptic against the background stars, makes it impossible to define an obvious celestial east and west.

Compass directions on earth are fixed, making the latitude and longitude system possible. But these directions are tilted at 23 1/2 degrees relative to the earth's orbit around the sun. The tropics extend for 23 1/2 degrees either side of the equator. The tropics refers to the zone where the sun is directly overhead at some point during the year.

The axial tilt of 23 1/2 degrees is also reflected in the Arctic and Antarctic Circles, these define the zones on the earth's surface where the sun does not always rise and set once every 24 hours. Summer in either the northern or southern hemisphere is defined as the period where that hemisphere is pointing toward the sun due to the axial tilt and the opposite hemisphere is pointing away from the sun.

The angle between the earth's polar axis and the plane of the earth's orbit around the sun varies. It is at 23 1/2 degrees north of the equator on the first day of the northern hemisphere summer and 23 1/2 degrees south of the equator on the first day of the northern hemisphere winter. The first day of summer and winter are known as the solstices.

It is only on the first days of spring and autumn that the sun is directly overhead at the equator so that night and day are of equal length. For this reason, these two days are known as the equinoxes, meaning equal length of day and night. The equinoxes are also the only two days when the earth's polar axis is perpendicular to the plane of the earth's orbit around the sun.

Celestial north and south in our new space locator grid are very clearly defined by the points that are always overhead at the poles. Since the polar axis is perpendicular to the plane of the earth's orbit around the sun at the two equinoxes, let's define a line from the center of the sun to the center of the earth, and continuing on into space, at the vernal equinox (first day of northern hemisphere spring) as celestial east (for Easter), and an opposite line at the autumnal equinox as celestial west.

The earth's surface is two-dimensional, while space is three-dimensional. This means that we require another line to express a point in space. This can only be a line from the earth's center at summer solstice, through the center of the sun, to the earth's center at winter solstice from the point of view of either one of the hemispheres. Let's call this the solstice line, it is perpendicular to both the polar axis and the equinox line.

To avoid confusion and errors, let's refer to the two opposite directions on the solstice line simply as celestial june and celestial december, since this is when the solstices fall. Use of three coordinates in space can precisely define any point in neighborhood of the solar system. Maybe the Celestial Meridian can be used for deeper space.

The orbit of any body in the solar system can be easily described mathematically by use of such a grid system. we could easily plot relative positions of planets and other objects for any given time. The grid locator system can be centered on either the earth or the sun, or any point for that matter such as a spaceship, with a constantly varying conversion factor between the two. This system could also benefit from the 180 degree trigonometric function that I described in the posting "New Trigonometric Functions" on this blog.