If you are out in the ﬁeld and are unable to access one of the many sky maps available in magazines or on the Internet, the planets can be difﬁcult to pick out from among the many bright stars. The only ones visible to the naked eye are Venus, Mars, Jupiter, and Saturn (Mercury requires exceptional conditions). Here is how to ﬁnd them.
Since the orbit of Venus is inside that of Earth, this planet never strays far from the Sun (47◦ at most, i.e. about 3 h of time). Look for it in the east before sunrise or in the west after sunset. At maximum brightness it is a spectacular object – the brightest in the night sky after the Moon.
Mars, Jupiter, and Saturn, whose orbits are outside the Earth’s, can appear at any time during the night, but only for part of the year. Look for them close to the track followed by the Sun during its day-time apparent trajectory (i.e. the ecliptic). Mars can be identiﬁed by its characteristic orange color. Jupiter is as bright as some of the brightest stars, while Saturn is the faintest of the visible planets.
When in doubt, there is a simple way to conﬁrm that one is really looking at a planet: stars twinkle but planets generally do not.