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In page Solstice:

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Unlike the equinox, the solstice time is not easy to determine. The changes in solar declination become smaller as the Sun gets closer to its maximum/minimum declination. The days before and after the solstice, the declination speed is less than 30 arcseconds per day which is less than 160 of the angular size of the Sun, or the equivalent to just 2 seconds of right ascension.[citation needed]