Faint Neptune joins Venus and Saturn to form a planetary triangle in the pre-dawn sky on April 28

Saturn, Venus and Neptune come together in the eastern pre-dawn sky on April 28 to form a planetary triangle, with Mercury hugging the horizon to the left.

The predawn hours of April 28 will see a planetary triangle form in the night sky, as Venus makes a close approach to Saturn following a conjunction, while Neptune, invisible to the naked eye, will sit just a few degrees away towards the horizon.

Saturn and Venus will be below the horizon for viewers in the U.S. when they reach the point of conjunction in the hours before their appearance on the morning of the 28th. A planetary conjunction occurs when two worlds share the same right ascension  —  a value similar to longitude that is used by astronomers to chart the locations of objects in the night sky  —  when viewed from the night sky from Earth.