Both planets will be visible to the naked eye for the next two weeks as bright, starlike objects that will dominate the low western sky shortly after sunset.
"From a place with a low horizon, one should be able to get a nice view of these two planets hanging in the darkening sky like gems," said Geza Gyuk, staff astronomer at the Adler Planetarium in Chicago.
As the cosmic duo climb higher, the'll reach conjunction—their closest approach to each other—on Saturday and Sunday.
Those nights the two planets will seem to be separated by only three degrees, or the equivalent of six full-moon disks.
Venus Guides Eyes to Mercury
Of the five planets visible to the naked eye, Mercury is usually the most challenging to see, because it never wanders far from the sun.
The innermost planet, Mercury orbits the sun so closely that a year lasts just 88 Earth days. (See pictures of Mercury taken by a passing spacecraft.)
As seen from Earth, Mercury tightly hugs the horizon, and it appears faint because it's swathed in the sun's glare.
"Most people never get to see Mercury, because it ... isn't very bright. But this conjunction is coming around Mercury's maximum elongation [the planet's farthest angle away from the sun] of 20 degrees on April 8," Gyuk said.
Brilliant Venus will serve as a guidepost for sky-watchers to easily find tiny Mercury. (Related: "Neptune Easier to Spot Now, Thanks to Jupiter.")
"Weather permitting," Gyuk said, "I'm certainly going to be out with my kids looking for Mercury!"
Full Planetary Collection
As an added bonus, planet-hunters already out to spy Venus and Mercury will be able to see all five naked-eye planets in a single night.
As darkness sets in, Mars will become visible directly overhead, appearing as a red-tinged, starlike object. A little later, Saturn will appear slightly above the eastern horizon and will rise higher during the night.
Finally, the gas-giant planet Jupiter will rise in the east just before sunrise.