Night sky or good binoculars, the planets appear as discs demonstrating finite size, and it is possible to observe orbiting moons which cast shadows onto the host planet's surface. Venus is the most prominent planet, often called the "morning star" or "evening star" because it is brighter than the stars and often the only "star" visible near sunrise or sunset, depending on its location in its orbit. Mercury, Mars, Jupiter and Saturn are also visible to the naked eye. Earth's Moon is a grey disc in the sky with cratering visible to the naked eye. It spans, depending on its exact location,
Deep-sky object objects". Since the definition is objects that are non-Solar System and non-stellar the list includes: Deep-sky object Deep-sky object (abbreviated as DSO) is a term designating any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself.