Look to the west-northwestern evening sky and you’ll see Jupiter, Mercury, and Venus gathering together in the evening sky.
The best time to see them, during this May 25 to May 28 time period, is about 30 to 45 minutes after the Sun sets in the western sky.
On May 26th, for instance, the three planets will be very close together, the closest you will see them during this event.
On May 27th, just one night later, Jupiter and Venus will be positioned side-by-side with respect to our viewpoint on Earth.
Even though the three planets appear to be very close together, this is only a mirage -- something that only appears to be so due to our viewing position here on Earth.
According to the May 21, 2013 Space.com article 3 Planets Performing Rare Night Sky Show: How to See It, “While the three planets appear tightly grouped in our night sky, in reality they're very far away from each other.”
And, “During the last week of May, Mercury, Venus and Jupiter will be about 105 million miles (169 million kilometers), 150 million miles (241 million km) and 565 million miles (909 million km) away from Earth, respectively, Sky & Telescope officials said.”
The YouTube video “Jupiter, Venus, and Mercury Meet in Western Twilight May 25-28, 2013”, as shown above, states, “Venus, Jupiter, and Mercury, shine together in the western twilight about half an hour after sunset in late May, according to the editors of StarDate magazine.” (http://www.youtube.com/watch?v=daOTyBnUdzc)