According to forecasts, on July 4, 2020, a rare and unique planet parade will occur. All the solar system planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune plus the dwarf planet Pluto – will line up on one side of the Sun at the same time.
The near-perfect alignment will not occur, as the deviation angle will be quite small, Report says citing Star Walk.
By planets' alignment or parade, astronomers usually mean that planets will appear in the same part of the sky. Sometimes the arrangement of planets resembles a line, but it's not always the case. Most often, two or three planets form a line in the sky.
Besides, a lot depends on the viewpoint. When planets line up on one side of the Sun, they are not necessarily in the same region of the sky for observers from Earth. Vice versa, when planets are in the same part of the sky from Earth's point of view, they are not necessarily aligned from the Sun.
The last parade of planets of this type occurred in 1982, and the next one is expected in 2161 and 2492.