Azerbaijan National Academy of Sciences

On July 4, 2020, a rare and unique celestial event, known as the "Parade of the Planets", will take place.

The term "planet parade" is widely used in astronomy to refer to an astronomical event that occurs when the planets of the solar system line up in the same area of ​​the sky, as is seen by observers on Earth.

Here are three commonly used definitions:

An astronomical event that occurs when planets line up on one side of the sun at the same time, as seen in the plane of our solar system.

Three planets are aligned twice a year, four planets once a year, five planets once every 19 years, and all eight planets of the solar system once every 170 years.

A visual phenomenon that occurs when the planets of the solar system appear in a small sector of the sky at the same time, regardless of the conditions of their visibility, as is seen by observers from the Earth.

A parade of planets of this type occurred on April 18, 2002, when all the planets of the solar system, visible with the naked eye, lined up in the evening sky. According to preliminary forecasts, such parades of the planets will take place in July 2020, in March and June 2022, in 2040 and 2854.

The following types of planetary parades differ in the number of planets involved:

Mini-planet parade - 3 planets.

Parade of minor planets - 4 planets.

Big planet parade - 5 or 6 planets.

The great (complete) parade of planets - all the planets of the solar system (sometimes Pluto).

Mini-parades of the planets is a common event. Three planets can be observed simultaneously in the same part of the sky several times a year.

According to forecasts, on July 4, 2020 a rare and unique parade of planets will take place. All the planets of the solar system - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune plus the dwarf planet Pluto - line up on one side of the star at the same time. It will be a parade of planets of the first type of the three described above. Almost perfect alignment will occur, the deviation angle will be quite small. The last parade of planets of this type occurred in 1982, and the next is expected in 2161 and 2492.

The parade of planets, which will take place almost all of July, cannot be observed completely. Uranus and Neptune are too far away, and from this distance they can not be seen with the naked eye. Saturn, Jupiter and Mars will be visible at night, and Venus in the morning. Mercury, in turn, is next to the Sun, so the star completely eclipses it.

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