Rendezvous at sunset: The two brightest planets in our sky, Jupiter and Venus, will come particularly close this evening. Shortly after sunset, the two planets are only 1.6 degrees apart in the sky – less than a finger’s width when your arm is outstretched. The two bright points of light above the western horizon cannot be overlooked even with the naked eye and outshine all the stars. Such a conjunction is not rare, but this time it was a particularly beautiful spectacle.
The two planets Jupiter and Venus are among the most prominent objects in the sky. Both are so bright that they outshine the stars and are clearly visible even at dusk. It happens again and again that these two planets, which are actually far apart from each other, appear to come very close to each other in the sky: Because Venus, our inner neighboring planet, orbits around the sun much faster than Jupiter, which orbits beyond Mars, it passes close to it in the sky around every ten to fifteen months – a planetary conjunction occurs.
In ancient times, such planetary conjunctions were often considered omens, divine indicators of special events. According to some astronomers, the biblical “Star of Bethlehem” could also have been such a conjunction.
Jupiter and Venus form a couple
This evening it’s that time again: Jupiter and Venus are coming very close to each other in the evening sky. After coming together for several days, they will be just 1.6 degrees apart in the western sky after sunset. The two bright planets are located around 45 minutes after sunset to the left of Castor and Pollux, the two bright head stars of the constellation Gemini. Venus is located above Jupiter to the right.
Although both planets appear almost the same size when they rendezvous in the sky, in reality they are not: Jupiter is around ten times the size of Earth, Venus is slightly smaller than our home planet. Because it is currently “only” around 180 million kilometers away from us, while Jupiter is around 900 million kilometers away, the gas giant appears to be hardly larger than Venus. In addition, its greater proximity to the sun and the highly reflective cloud cover give Venus additional brightness, so that it appears significantly brighter in the sky than distant Jupiter.
The bright points of light from Jupiter and Venus are prominently visible in the evening sky, even with the naked eye. With a small telescope you can also see three of Jupiter’s four large moons: the innermost moon Io, as well as Europa and Callisto on the other side of Jupiter.
Mercury and the crescent moon as companions
But Jupiter and Venus are not alone: To the right, below the two planets that are close together, is the innermost planet Mercury in the evening sky. From around 9:30 p.m. it can be seen as a point of light diagonally to the right below Venus and Jupiter, low above the northwest horizon, but it sets again around an hour later. From June 16th to 18th, another celestial body will join this trio: the narrow crescent moon will pass close to the planet on these evenings – a particularly beautiful sight.
Jupiter and Venus will gradually move away from each other again from June 9th, Jupiter will sink lower and lower towards the horizon, while Venus will rise higher and will remain a prominent “evening star” for the rest of the summer. Both planets can still be seen relatively close to each other until the middle of the month.
Source: Sky & Telescope, NASA