English: The figure illustrates the equator system and its coordinates right ascension and declination. It shows a section of the sky measuring 360° × 100° with the celestial equator running through the center (black straight line). In addition, the ecliptic (the Sun's annual path among the stars) is shown with orange color. The position of a celestial body can be indicated in the equatorial system with two spherical coordinates, the right ascension α (alpha) and the declination δ (delta). The right ascension is measured from the vernal equinox, which, as here, is traditionally marked with a stylized ram's head. It is defined as the point in the ecliptic where the Sun in spring crosses the celestial equator going north. The right ascension increases to the left. Values on the figure are given both in angle measure and in time measure. Since 24h corresponds to 360°, 1h must correspond to 15°. The declination is measured perpendicular to the equator growing towards the north pole of the sky. The position of the Sun (☉) is marked in three places in the orbit. To the right of the spring point, where its coordinates are (α☉, δ☉) = (0°, 0°). Furthermore, 70° further forward in the ecliptic; here its coordinates are (α☉, δ☉) = (68° 22′, 26° 57′) = (4h 33m, 26° 57′). And on the left, the Sun's longitude in the ecliptic is 270°, it is the winter solstice, and its coordinates are (α☉, δ☉) = (270°, −23° 27′) = (18h, −23° 27′). The brightest star in the sky, Sirius, is marked in blue. The coordinates of the star are (α*, δ*) = (101° 17′, −16° 43′) = (6h 45m, −16° 43′). Near the north pole of the sky (δ = 90°, outside the picture) you find the bright star Polaris, whose coordinates are (α*, δ*) = (2h 32m, 89° 16′). Some of the constellations in the sky are included in the illustration. From left to right, it is Aquila (Eagle), Scorpius (Scorpion), Boötes (Herdsman), Virgo (Virgin), Leo (Lion), Orion and Pegasus with the Pegasus quadrangle.