Back قوس المراقبة Arabic Arc d'observació Catalan Observation arc English Arco de observación Spanish قوس مشاهده Persian Arc d'observation French Лак на набљудување Macedonian Arco de observação Portuguese Дуга наблюдения Russian Gözlem yayı Turkish
An observation arc (or arc length) of a Solar System body is the amount of time between its earliest and latest observations. It is used for finding its path. It is usually given in days or years. It is used asteroids and comets to find where they go.