# What are the coordinates of the equatorial system?

Equatorial Coordinate System. This is the preferred coordinate system to pinpoint objects on the celestial sphere. The equatorial coordinate system is basically the projection of the latitude and longitude coordinate system we use here on Earth, onto the celestial sphere.

Similarly one may ask, how are celestial coordinates measured?

The corresponding coordinate in the sky is called right ascension. Unlike longitude, which is measured in degrees and minutes, right ascension is measured in hours and minutes. There are 24 hours of right ascension corresponding to the full sweep of 360 degrees around the celestial equator.

What does RA and DEC stand for in astronomy?

RA (right ascension) and DEC (declination) are to the sky what longitude and latitude are to the surface of the Earth. RA corresponds to east/west direction (like longitude), while Dec measures north/south directions, like latitude. RA is indeed measured in hours, minutes, and seconds.

What is right ascension and declination in astronomy?

Right ascension and declination as seen on the inside of the celestial sphere. The primary direction of the system is the March equinox, the ascending node of the ecliptic (red) on the celestial equator (blue). Right ascension is measured eastward up to 24h along the celestial equator from the primary direction.

## What is Topocentric coordinates?

Geocentric coordinates are an Earth-centered system of locating astronomical objects in the Solar System in three dimensions along the Cartesian X, Y, and Z axes. They are differentiated from topocentric coordinates, which use the observer’s location as the reference point for bearings in altitude and azimuth.

## What is the celestial coordinate system?

In astronomy, a celestial coordinate system is a system for specifying positions of celestial objects: satellites, planets, stars, galaxies, and so on. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth.

## What is RA and DEC?

RA (right ascension) and DEC (declination) are to the sky what longitude and latitude are to the surface of the Earth. RA corresponds to east/west direction (like longitude), while Dec measures north/south directions, like latitude. RA is indeed measured in hours, minutes, and seconds.

## What is the celestial equatorial system?

The Equatorial Coordinate System is generally the preferred way astronomers use to keep track of the positions of objects in the sky. Astronomers imagine that the Earth is surrounded by a large sphere called the celestial sphere. The Earth’s equator and the plane of the Earth’s orbit are projected onto this sphere.

## What are the coordinates of the equator?

The north pole is 90° N; the south pole is 90° S. The 0° parallel of latitude is designated the equator, the fundamental plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres.

## What are the coordinates of the South Pole?

The geographic coordinates of the South Pole are usually given simply as 90°S, since its longitude is geometrically undefined and irrelevant. When a longitude is desired, it may be given as 0°. At the South Pole, all directions face north.

## What is a horizontal coordinate?

The horizontal coordinate system is a celestial coordinate system that uses the observer’s local horizon as the fundamental plane. It is expressed in terms of altitude (or elevation) angle and azimuth.

## What is the azimuth of due west?

By the way, for azimuth 0° people often say ‘due’ north (‘due’ means ‘exactly’), and for 90° they say due east, for 180° due south and for 270° due west!”

## What is the main reference line in the celestial sphere?

an imaginary circle created by extending Earth’s equator into space; the main reference line in the celestial sphere. a coordinate used on the celestial sphere, just latitude is used on Earth.

## What is the apparent path of the sun called?

The apparent path of the Sun’s motion on the celestial sphere as seen from Earth is called the ecliptic. The ecliptic plane is tilted 23.5° with respect to the plane of the celestial equator since the Earth’s spin axis is tilted 23.5° with respect to its orbit around the sun.

## What are the lines of latitude?

Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth.

## What is the north celestial pole?

The North Celestial Pole is the point in the sky about which all the stars seen from the Northern Hemisphere rotate. The North Star, also called Polaris, is located almost exactly at this point in the sky.

## Where is the zenith?

Zenith. Zenith, point on the celestial sphere directly above an observer on the Earth. The point 180° opposite the zenith, directly underfoot, is the nadir. Astronomical zenith is defined by gravity; i.e., by sighting up a plumb line.

## How is right ascension measured?

Right ascension (abbreviated RA; symbol α) is the angular distance measured eastward along the celestial equator from the Sun at the March equinox to the hour circle of the point above the earth in question.

## What type of line is the Prime Meridian?

A prime meridian is a meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its antimeridian (the 180th meridian in a 360°-system) form a great circle. This great circle divides the sphere, e.g., Earth, into two hemispheres.

90 degrees

## What is the declination of the South Pole?

The coordinate indicating where an object is between those poles is declination. Declination is measured from the celestial equator. It extends from 0° at the celestial equator to +90° at the north celestial pole and from 0° at celestial equator to -90° at the south celestial pole.

## What is the altitude of the horizon?

Altitude is the angle up from the horizon. Zero degrees altitude means exactly on your local horizon, and 90 degrees is “straight up”. Hence, “directly underfoot” is -90 degrees altitude. Azimuth is the angle along the horizon, with zero degrees corresponding to North, and increasing in a clockwise fashion.

## What is the declination of the celestial equator?

Analogous to the latitude on Earth, the Declination of an object on the celestial sphere is measured northward or southward from the plane containing the equator. The declination of the equator is 0 degrees, the North Celestial Pole, +90 degrees, the South Celestial Pole, -90 degrees.

## What is the ecliptic longitude?

Earth-centered ecliptic coordinates as seen from outside the celestial sphere. Ecliptic longitude (red) is measured along the ecliptic from the vernal equinox. Ecliptic latitude (yellow) is measured perpendicular to the ecliptic.