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Autumn 2021. Astronomical autumn – when does it start? The autumn equinox [Data]

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Wednesday is the last day of summer and the beginning of the astronomical fall. Thus, we will welcome the new season. When exactly does astronomical autumn begin and what attractions in the sky await us in the coming months? Check.

Today we will say goodbye to summer and welcome an astronomical autumn. The days are getting shorter and the nights are getting longer. Yellow and orange leaves grow on the trees, and at night the temperature is getting lower.

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Autumn equinox 2021. Astronomical autumn. Date

When is the first day of astronomical autumn this year? The period from the autumn equinox to the winter solstice is considered to be astronomical autumn in our hemisphere. The autumn equinox occurs when the sun passes through the point of Libra. The Earth then crosses the point on its orbit where the sun’s rays fall perpendicular to the equator and are simultaneously tangent to its surface at the poles.

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The time of the fall equinox usually falls on September 22 or 23. We will welcome the astronomical autumn on Wednesday, September 22 at 21:21. The autumn equinox also takes place on this day.

Calendar autumn 2021. Date

The beginning of calendar seasons always falls on one specific day. The first day of calendar fall in autumn 2021 falls on September 23. It will last until December 21 – then the calendar winter will begin.

Weather autumn 2021

In addition to the calendar and astronomical autumn, we also know the concept of meteorological autumn. The weather autumn always falls on the same period. It starts on September 1 and ends on November 30. This concept was introduced by meteorologists and climatologists. It is used to always refer to the same period when comparing statistical or climatic data, because astronomical and thermal seasons have “moving” dates.

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Autumn bird migrationMaria Samczuk / Adam Ziemienowicz / PAP

Autumn 2021. Astronomy attractions. What to see in the sky

On autumn evenings, Venus will shine from the planets, the visibility conditions will improve. It will be set about an hour after sunset at the end of October. Jupiter and Saturn will be visible all the time, shining on the southern side of the sky.

In turn, we will not see Mars in the evenings. The Red Planet will begin rising in the morning in late October / early November. Mercury will not be visible at the beginning of autumn, but in the second half of October we will see it in the morning sky. It will be visible for the longest time around October 20 (sunrise about an hour before dawn).

On the other hand, planets that are invisible to the naked eye, but visible with a telescope in autumn, can be used to observe both Uranus and Neptune. The upcoming fall will be their best season of visibility.

The time of the Perseids and other summer meteor showers are over, but that doesn’t mean you can’t see “shooting stars” in the fall. For example, from October 6-10, the very slow Draconids associated with comet 21P / Giacobini-Zinner are active.

Besides, the Orionid period falls from October 2 to November 7, with a maximum of October 21. This swarm is related to the famous comet Halley. The most active of the meteor showers, however, are the Geminids visible from December 4 to 17. At the maximum around December 14, their activity can reach even 120 phenomena per hour. Geminids are related to the asteroid 3200 Phaeton.

Heaven in OctoberPAP / Maria Samczuk

Main photo source: Shutterstock



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