Voiko Venuksen nähdä pelkästään silmillä?
Five planets can be recognized as planets from Earth with the naked eye: Mercury, Venus, Mars, Jupiter, and Saturn. Under typical dark sky conditions Uranus (magnitude +5.8) can be seen as well with averted vision, as can the asteroid Vesta at its brighter oppositions. The Sun and the Moon—the remaining noticeable naked-eye objects of the solar system—are sometimes added to make seven "planets." During daylight only the Moon and Sun are obvious naked eye objects, but in many cases Venus can be spotted in daylight and in rarer cases Jupiter. Close to sunset and sunrise bright stars like Sirius or even Canopus can be spotted with the naked eye as long as one knows the exact position in which to look.
Historically, the zenith of naked-eye astronomy was the work of Tycho Brahe (1546–1601). He built an extensive observatory to make precise measurements of the heavens without any instruments for magnification. In 1610, Galileo Galilei pointed a telescope towards the sky. He immediately discovered the moons of Jupiter and the phases of Venus, among other things.
Venus can be spotted in daylight