Jupiter, Venus and Mercury are beginning to gather in the tightest grouping to take place until 2021, according to Sky & Telescope.

All three are presently visible with the naked eye, permitting even the most amateur of stargazers to observe the coalescence of the celestial bodies over the next week.

In fact, Jupiter and Venus, the two brightest planets in the solar system, have been approaching each other for weeks now; Mercury, however, is just now joining the others and together, the three will fit into a circle 5 degrees wide, or half the width of a clenched fist held at arm’s length, by May 24.

By May 26, the planets will fit into a space half that size and by May 27, they will appear side-by-side.

From there, Jupiter will begin sliding downward in the sky until it will disappear completely by early June.

Mercury will do the opposite, climbing higher above Venus in what will be its best evening apparition of 2013, according to Sky & Telescope. After peaking on June 7, however, it will follow in Jupiter’s footsteps in sinking back behind the horizon. As it does so, it will grow dimmer and dimmer.

Venus, all the while, will continue to hold steady throughout the rest of the year, shining as brightly as ever.

Triple conjunctions are a relatively rare phenomenon with the last one occurring in May 2011 and the next one not taking place until October 2015, though the latter will not be as close as this year’s.

To catch the show, NASA suggests stepping outside roughly 30 to 60 minutes after sunset and looking west and toward the horizon, letting Venus – the brightest – star act as a guide.

But don’t be fooled – as close as the planets may appear here from Earth, during the last week of May, Mercury, Venus and Jupiter will be about 105 million miles, 150 million miles and 565 million miles away from here, respectively, according to Sky & Telescope.

Updated: Previously, the third paragraph stated that Mars was joining the other planets; however, the correct planet is Mercury.