# What are the right ascension and Declination coordinates on March 21st?

## What are the right ascension and Declination coordinates on March 21st?

0 hours right ascension is by convention the right ascension of the sun on the vernal equinox, March 21. So your object is 3h 5m 38s east of the vernal equinox. Declination is measured in degrees, arcminutes, and arcseconds. There are 60 arcmin in a degree, and 60 arcsec in an arcmin.

### What is the right ascension and Declination for the vernal equinox?

Vernal Equinox: The point where the Sun crosses the celestial Equator and has zero Declination and is considered to be the zero for the Right Ascension in hours (h) or degrees (^o).

#### What is the right ascension of the sun on March 21?

A bit more on seasons

Approx. Date Label Sun’s Right Ascension
March 21 Vernal Equinox 0 hours
June 21 Summer Solstice 6 hours
Sept 21 Fall Equinox 12 hours
Dec 21 Winter Solstice 18 hours

What is the right ascension of the spring equinox?

The zero-point for right ascension is the Vernal Equinox (also called the Aries Point in the text), location on the celestial equator of sunrise on the first day of spring. The total range of right ascension is 24 hrs = 360 deg / 15 deg/hr. The 15 deg/hr conversion factor arises from the rotation rate of the Earth.

How do you explain right ascension?

Right ascension, in astronomy, the east–west coordinate by which the position of a celestial body is ordinarily measured; more precisely, it is the angular distance of a body’s hour circle east of the vernal equinox, measured along the celestial equator. The symbol for right ascension is the Greek letter α (alpha).

## What is declination equivalent to?

Declination (DEC) is the celestial sphere’s equivalent of latitude and it is expressed in degrees, as is latitude. For DEC, + and – refer to north and south, respectively. The celestial equator is 0° DEC, and the poles are +90° and -90°. Right ascension (RA) is the celestial equivalent of longitude.

### Why is it called right ascension?

How right ascension got its name. Ancient astronomy was very concerned with the rise and set of celestial objects. The ascension was the point on the celestial equator (red) which rose or set at the same time as an object (green) on the celestial sphere.

#### How do you calculate the right ascension?

The right ascension is the angular distance of a body’s hour circle east of the vernal equinox which is measured along the celestial equator. The total range of the right ascension is 24 hours = 360 degree / 15 degree / hour. The 15 degrees/hour conversion factor rises from the rotation rate of the Earth.

Does right ascension and declination change?

Because the coordinate grid insists on sliding around this way, a star’s right ascension and declination are continually changing. To fix a star’s position you need to specify the date for which a right ascension and declination apply.

What is right ascension equivalent to?

longitude
Right ascension (RA) is the celestial equivalent of longitude. RA can be expressed in degrees, but it is more common to specify it in hours, minutes, and seconds of time: the sky appears to turn 360° in 24 hours, or 15° in one hour. So an hour of RA equals 15° of sky rotation.

## What is the range of values for right ascension?

0h to 24h.
Because the stars circle about the sky every 24 hours, right ascension or RA ranges from 0h to 24h.

### Is the vernal equinox the zero point for right ascension?

Equinoxes and Solstices. The zero point for celestial longitude (that is, for right ascension) is the Vernal Equinox, which is that intersection of the ecliptic and the celestial equator near where the Sun is located in the Northern Hemisphere Spring. The other intersection of the Celestial Equator and the Ecliptic is termed the Autumnal Equinox.

#### When is the Sun at the vernal equinox?

The other intersection of the Celestial Equator and the Ecliptic is termed the Autumnal Equinox. When the Sun is at one of the equinoxes the lengths of day and night are equivalent (equinox derives from a root meaning “equal night”). The time of the Vernal Equinox is typically about March 21 and of the Autumnal Equinox about September 22.

Where does the right ascension of the Sun take place?

Right ascension is measured from the Sun at the March equinox i.e. the First Point of Aries, which is the place on the celestial sphere where the Sun crosses the celestial equator from south to north at the March equinox and is currently located in the constellation Pisces.

Which is the astronomical equivalent of right ascension?

Astronomical equivalent of longitude. Right ascension (abbreviated RA; symbol α) is the angular distance of a particular point 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.

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